#!/usr/bin/perl
# nagios: +epn
use FindBin qw ($Bin);
use Nagios::Plugin::Functions;
use JMX::Jmx4Perl::Nagios::CheckJmx4Perl;
# Hack for avoiding a label in front of "OK" or "CRITICAL", in order to conform
# to the usual Nagios conventions and to avoid redundancy in the UI display.
BEGIN {
no warnings 'redefine';
*Nagios::Plugin::Functions::get_shortname = sub {
return undef;
};
}
# Create new object and use this for the check
# Hopefully it gets cleaned up aftewards if running
# within the embedded Nagios perl interpreter. At least,
# we don't keep any references.
JMX::Jmx4Perl::Nagios::CheckJmx4Perl->new(@ARGV)->execute();
=head1 NAME
check_jmx4perl - Nagios plugin using jmx4perl for accessing JMX data remotely
=head1 SYNOPSIS
# Check for used heap memory (absolute values)
check_jmx4perl --url http://localhost:8888/jolokia \
--name memory_used \
--mbean java.lang:type=Memory \
--attribute HeapMemoryUsage \
--path used \
--critical 10000000 \
--warning 5000000
# Check that used heap memory is less than 80% of the available memory
check_jmx4perl --url http://localhost:8888/jolokia \
--alias MEMORY_HEAP_USED \
--base MEMORY_HEAP_MAX \
--critical :80
# Use predefined checks in a configuration file with a server alias
# Server alias is 'webshop', check is about requests per minute for the
# servlet 'socks_shop'
check_jmx4perl --config /etc/nagios/check_jmx4perl/tomcat.cfg
--server webshop \
--check tc_servlet_requests \
--critical 1000 \
socks_shop
# Check for string values by comparing them literally
check_jmx4perl --url http://localhost::8888/jolokia \
--mbean myDomain:name=myMBean \
--attribute stringAttribute \
--string \
--critical 'Stopped' \
--warning '!Started'
# Check that no more than 5 threads are started in a minute
check_jmx4perl --url http://localhost:8888/jolokia \
--alias THREAD_COUNT_STARTED \
--delta 60 \
--critical 5
# Execute a JMX operation on an MBean and use the return value for threshold
# Here a thread-deadlock is detected.
check_jmx4perl --url http://localhost:8888/jolokia \
--mbean java.lang:type=Threading \
--operation findDeadlockedThreads \
--null no-deadlock \
--string 1 \
--critical !no-deadlock \
--critical 10
# Use check_jmx4perl in proxy mode
check_jmx4perl --url http://localhost:8888/jolokia \
--alias MEMORY_HEAP_USED \
--critical 10000000 \
--target service:jmx:rmi:///jndi/rmi://bhut:9999/jmxrmi
=head1 DESCRIPTION
C<check_jmx4perl> is a Nagios plugin for monitoring Java applications. It uses
an agent based approach for accessing JMX exposed information remotely.
Before start using C<check_jmx4perl> an agent must be installed on the target
platform. For JEE application server this is a simple webapplication packaged
as a C<war> archive. For other platforms, other agents are available,
too. Please refer to the C<README> for installation instructions and the
supported platforms.
C<check_jmx4perl>s can also be used in an agentless mode (i.e. no agent needs
to be installed on the target platform). See L</"Proxy mode"> for details.
This plugin can be configured in two ways: Either, all required parameters for
identifying the JMX information can be given via the command line. Or, a
configuration file can be used to define one or more Nagios checks. This is the
recommended way, since it allows for more advanced features not available when
using the command line alone. Each command line argument has an equivalent
option in the configuration files, though.
This documentation contains four parts. First, a L<tutorial|/"TUTORIAL"> gives
a 5 minute quickstart for installing and using C<check_jmx4perl>. The middle
part offers some technical background information on JMX itself, the
L<features|/"REFERENCE"> provided by this plugin and finally the L<command line
arguments|/"COMMAND LINE"> and the L<configuration file|/"CONFIGURATION">
directives are described.
=head1 TUTORIAL
Before we dive into the more nifty details, this 5 minutes quickstart gives
a simple cooking recipe for configuration and setup of C<check_jmx4perl>.
=over
=item *
This tutorial uses I<tomcat> as an application server. Download it from
L<http://tomcat.apache.org> (either version 5 or 6) and extract it:
$ tar zxvf apache-tomcat-*.tar.gz
$ # We need this variable later on:
$ TC=`pwd`/apache-tomcat*
=item *
Download I<jmx4perl> from L<http://search.cpan.org/~roland/jmx4perl> and install
it:
$ tar zxvf jmx4perl-*.tar.gz
$ cd jmx4perl*
$ # Store current directory for later reference:
$ J4P=`pwd`
$ perl Build.PL
$ sudo ./Build install
This is installs the Perl modules around C<JMX::Jmx4Perl> which can be used for
programmatic JMX access. There are some CPAN dependencies for jmx4perl, the
build will fail if there are missing modules. Please install the missing
modules via cpan (C<cpan I<module>>). The Nagios plugin C<check_jmx4perl> is
installed in a standard location (F</usr/bin>, F</usr/local/bin> or whatever
your Perl installation thinks is appropriate) as well as the other scripts
C<jmx4perl> (a generic tool for accessing JMX) and C<j4psh> (an interactive JMX
shell).
=item *
Deploy the Jolokia agent in Tomcat:
$ cd $TC/webapps
$ jolokia
=item *
Start Tomcat:
$ $TC/bin/startup.sh
=item *
Check your setup:
$ jmx4perl http://localhost:8080/jolokia
This prints out a summary about your application
server. L<http://localhost:8080/jolokia> is the URL under which the agent is
reachable. Tomcat itself listens on port 8080 by default, and any autodeployed
war archive can be reached under its filename without the .war suffix (jolokia in
this case).
=item *
Try a first Nagios check for checking the amount of available heap memory in
relation to the maximal available heap:
$ check_jmx4perl --url http://localhost:8080/jolokia \
--mbean java.lang:type=Memory \
--attribute HeapMemoryUsage \
--path used \
--base java.lang:type=Memory/HeapMemoryUsage/max \
--warning 80 \
--critical 90
OK - [java.lang:type=Memory,HeapMemoryUsage,used] : In range 9.83% (12778136 / 129957888) |
'[java.lang:type#Memory,HeapMemoryUsage,used]'=12778136;103966310.4;116962099.2;0;129957888
where
=over
=item --url http://localhost:8080/jolokia
is the agent URL
=item --mbean java.lang:type=Memory
is the MBean name
=item --attribute HeapMemoryUsage
is the attribute to monitor
=item --path used
is an inner path (see L</"Paths">), which specifies an inner value within a
more complex structure. The value C<HeapMemoryUsage> is a composed value (Jav
type: CompositeData) which combines multiple memory related data. The complete
value can be viewed with I<jmx4perl>:
$ jmx4perl http://localhost:8080/jolokia read java.lang:type=Memory HeapMemoryUsage
{
committed => 85000192,
init => 0
max => 129957888,
used => 15106608,
}
=item --base java.lang:type=Memory/HeapMemoryUsage/max
is the base value for which a relative threshold should be applied. This is a
shortcut notation in the format I<mbean>C</>I<attribute>C</>I<path>.
=item --warning 80
is the warning threshold in percent. I.e. a C<WARNING> will be raised by this
plugin when the heap memory usage is larger than 80% of the maximal available
heap memory for the application server (which is I<smaller> than the available
memory of the operating system)
=item --critical 90
is the critical threshold in percent. If the available heap memory reaches 90%
of the available heap, a C<CRITICAL> alert will be returned.
=back
All available command line options are described in L</"COMMAND LINE">.
=item *
For more complex checks the usage of a configuration file is recommended. This
also allows you to keep your Nagios service definitions small and tidy. E.g. for
monitoring the number of request per minute for a certain web application, a
predefined check is available:
$ check_jmx4perl --url http://localhost:8080/jolokia \
--config $J4P/config/tomcat.cfg \
--critical 100 \
--check tc_servlet_requests \
jolokia-agent
OK - 15.00 requests/minute | 'Requests jolokia-agent'=15;5000;100
where
=over
=item --config $J4P/config/tomcat.cfg
is the path to configuration file. There a several predefined checks coming
with this distribution, which are documented inline. Look there for some
inspiration for what to check.
=item --critical 100
A threshold von 100, i.e. the checked value must be 100 or less, otherwise a
critical alert is raised.
=item --check tc_servlet_requests
is the name of the check to perform which must be defined in the configuration
file
=item jolokia-agent
is an extra argument used by the predefined check. It is the name of the
servlet for which the number of requests should be monitored. To get the name
of all registered servlets use C<jmx4perl list>:
$ jmx4perl http://localhost:8080/jolokia list | grep j2eeType=Servlet
The servlet name is the value of the C<name> property of the listed MBeans.
=back
Configuration files are very powerful and are the recommended way for
configuring C<check_jmx4perl> for any larger installation. Features like multi
checks are even only available when using a configuration file. The syntax for
configuration files are explained in depth in L</"CONFIGURATION">.
=item *
Finally, a Nagios service definition needs to be added. For the memory example
above, a command for relative checks can be defined:
define command {
command_name check_jmx4perl_relative
command_line $USER3$/check_jmx4perl \
--url $ARG1$ \
--mbean $ARG2$ \
--attribute $ARG3$ \
--path $ARG4$ \
--base $ARG5$ \
$ARG6$
}
Put this into place where you normally define commands (either in the global
Nagios F<commands.cfg> or in a specific commands configuration file in the
commands directory). C<$USER3> is a custom variable and should point to the
directory where C<check_jmx4perl> is installed (e.g. F</usr/local/bin>).
The service definition itself then looks like:
define service {
service_description j4p_localhost_memory
host_name localhost
check_command check_jmx4perl_relative \
!http://localhost:8080/jolokia \
!java.lang:type=Memory \
!HeapMemoryUsage \
!used \
!java.lang:type=Memory/HeapMemoryUsage/max \
!--warning 80 --critical 90
}
Add this section to your service definitions (depending on your Nagios
installation). This example adds a service to host C<localhost> for checking the
heap memory, raising a C<WARNING> if 80% of the available heap is used and a
C<CRITICAL> if more than 90% of the heap memory is occupied.
=back
Installing and using jmx4perl is really that easy. The Nagios configuration in
this example is rather simplistic, of course a more flexible Nagios setup is
possible. The blog post
L<http://labs.consol.de//blog/jmx4perl/check_jmx4perl-einfache-servicedefinitionen/>
(written by Gerhard Lausser) shows some advanced configuration setup. (It is in
german, but the automatic translation from L<http://bit.ly/bgReAs> seems to be
quite usable).
=head1 REFERENCE
This section explains the JMX basics necessary to better understand the usage
of C<check_jmx4perl>. It tries to be as brief as possible, but some theory is
required to get the link to the Java world.
=head2 MBeans
JMX's central entity is an C<MBean>. An MBean exposes management information in
a well defined way. Each MBean has a unique name called I<Object Name> with the
following structure:
domain:attribute1=value1,attribute2=value2, .....
E.g.
java.lang:type=Memory
points to the MBean which lets you access the memory information of the target
server.
Unfortunately, except for so called I<MXBeans>
(L<http://java.sun.com/j2se/1.5.0/docs/api/java/lang/management/package-summary.html>)
there is no standard naming for MBeans. Each platform uses its own. There used
to be a naming standard defined in B<JSR77>
(L<http://jcp.org/en/jsr/detail?id=77>), unfortunately it was never widely
adopted.
There are various ways for identifying MBeans on a server:
=over
=item *
Use C<jmx4perl --list> to list all registered MBeans. In addition C<jmx4perl
--attributes> dumps out all known MBean attributes along with their values.
(Be careful, the output can be quite large)
=item *
Use C<j4psh> for interactively exploring the JMX namespace.
=item *
Use an alias. An alias is a shortcut for an MBean name, predefined by
L<JMX::Jmx4Perl>. All known aliases can be shown with C<jmx4perl aliases>.
Since each platform can have slightly different MBean names for the same
information, this extra level of indirection might help in identifying
MBeans. See L</"Aliases"> for more about aliases.
=item *
Use a predefined check. C<check_jmx4perl> comes with quite some checks
predefined in various configuration files. These are ready for use out of the
box. L</Predefined checks> are described in an extra section.
=item *
Ask your Java application development team for application specific MBean names.
=back
=head2 Attributes and Operations
C<check_jmx4perl> can obtain the information to monitor from two sources:
Either as MBean I<attributes> or as a return value from JMX I<operations>.
Since JMX values can be any Java object, it is important to understand, how
C<check_jmx4perl> (or I<jmx4perl> in general) handles this situation.
Simple data types can be used directly in threshold checking. I.e. the
following data types can be used directly
=over
=item *
Integer
=item *
Long
=item *
Float
=item *
Double
=item *
Boolean
=item *
String
=back
C<String> and C<Boolean> can be used in I<string> checks only, whereas the others
can be used in both, I<numeric> and I<string> checks (see L</"String checks">).
For numeric checks, the threhsholds has to be specified according to the format
defined in
L<http://nagiosplug.sourceforge.net/developer-guidelines.html#THRESHOLDFORMAT>
=head3 Paths
For more complex types, C<check_jmx4perl> provides the concept of so called
I<paths> for specifying an inner attribute of a more complex value. A path
contains parts separated by slashes (/). It is similar to an XPath expression
for accessing parts of an XML document. Each part points to an inner level of
a complex object.
For example, the MBean C<java.lang:type=Memory> exposes an attribute called
C<HeapMemoryUsage>. This attribute is a compound data type which contains
multiple entries. Looking with C<jmx4perl> at this attribute
$ jmx4perl http://localhost:8080/jolokia read java.lang:type=Memory HeapMemoryUsage
{
committed => 85000192,
init => 0
max => 129957888,
used => 15106608,
}
it can be seen, that there are 4 values coming with the reponse. With a path
C<used> one can directly pick the used heap memory usage (8135440 bytes in this
case) which then can be used for a threshold check.
$ check_jmx4perl --url http://localhost:8080/jolokia \
--mbean java.lang:type=Memory \
--attribute HeapMemoryUsage \
--path used \
--critical 100000000
OK - [java.lang:type=Memory,HeapMemoryUsage,used] : Value 10136056 in range | ...
=head3 Attributes
Attributes are values obtained from MBean properties. Complex values are
translated into a JSON structure on the agent side, which works for most
types. To access a single value from a complex value, the path mechanism
described above can be used. Thresholds can be applied to simple data types
only, so for complex attributes a path is I<required>.
=head3 Operations
The return values of operations can be used for threshold checking, too. Since
a JMX exposed operation can take arguments, these has to be provided as extra
arguments on the command line or in the configuration. Due to the agent's
nature and the protocol used (JSON), only simple typed arguments like strings,
numbers or booleans ("true"/"false") can be used.
Example:
$ check_jmx4perl --url http://localhost:8888/jolokia \
--mbean jolokia:type=Runtime \
--operation getNrQueriesFor \
--critical 10 \
"operation" \
"java.lang:type=Memory" \
"gc"
This example contacts a MBean C<jolokia:type=Runtime> registered by the jolokia
agent in order to check for the number of queries for a certain MBean via this
agent. For this purpose an JMX operation C<getNrQueriesFor> is exposed which
takes three arguments: The type ("operation"/"attribute"), the MBean's
ObjectName and the operation/attribute name which was called.
If the opertion to be called is an I<overloaded operation> (i.e. an operation
whose name exists multiple times on the same MBean but with different parameter
types), the argument types must be given within parentheses:
--operation checkUserCount(java.lang.String,java.lang.String)
=head2 Aliases
Aliases are shortcut for common MBean names and attributes. E.g. the alias
C<MEMORY_HEAP_MAX> specifies the MBean C<java.lang:type=Memory>, the attribute
C<HeapMemoryUsage> and the path C<max>. Aliases can be specified with the
C<--alias> option or with the configuration directive C<Alias>. Aliases can be
translated to different MBean names on different application server. For this
C<check_jmx4perl> uses an autodetection mechanism to determine the target
platform. Currently this mechanism uses one or more extra server
round-trips. To avoid this overhead, the C<--product> option (configuration:
C<Product>) can be used to specify the target platform explicitely. This is
highly recommended in case you are using the aliasing feature.
Aliases are not extensible and can not take any parameters. All availables
aliases can be viewed with
jmx4perl aliases
A much more flexible alternative to aliases are I<parameterized checks>, which
are defined in a configuration file. See L</CONFIGURATION> for more details
about parameterized checks.
=head2 Relative Checks
Relative values are often more interesting than absolute numbers. E.g. the
knowledge that 140 MBytes heap memory is used is not as important as the
knowledge, that 56% of the available memory is used. Relative checks calculate
the ratio of a value to a base value. (Another advantage is that Nagios service
definitions for relative checks are generic as they can be applied for target
servers with different memory footprints).
The base value has to be given with C<--base> (configuration: C<Base>). The
argument provided here is first tried as an alias name or checked as an
absolute, numeric value. Alternatively, you can use a full MBean/attribute/path
specification by using a C</> as separator, e.g.
... --base java.lang:type=Memory/HeapMemoryUsage/max ...
If one of these parts (the path is optional) contains a slash within its name,
the slash must be escaped with a backslash (\/). Backslashes in MBean names are
escaped with a double backslash (\\).
Alternatively C<--base-mbean>, C<--base-attribute> and C<--base-path> can be
used to specify the parts of the base value separately.
Example:
check_jmx4perl --url http://localhost:8080/jolokia \
--value java.lang:type=Memory/HeapMemoryUsage/used \
--base java.lang:type=Memory/HeapMemoryUsage/max \
--critical 90
check_jmx4perl --url http://localhost:8080/jolokia \
--value java.lang:type=Memory/HeapMemoryUsage/used \
--base-mbean java.lang:type=Memory \
--base-attribute HeapMemoryUsage \
--base-path max \
--critical 90
This check will trigger a state change to CRITICAL if the used heap memory will
exceed 90% of the available heap memory.
=head2 Incremental Checks
For some values it is worth monitoring the increase rate (velocity). E.g. for
threads it can be important to know how fast threads are created.
Incremental checks are switched on with the C<--delta> option (configuration:
C<Delta>). This option takes an optional argument which is interpreted as
seconds for normalization.
Example:
check_jmx4perl --url http://localhost:8080/jolokia \
--mbean java.lang:type=Threading \
--attribute TotalStartedThreadCount \
--delta 60 \
--critical 5
This will fail as CRITICAL if more than 5 threads are created per minute (60
seconds). Technically C<check_jmx4perl> uses the I<history> feature of the jolokia
agent deployed on the target server. This will always store the result and the
timestamp of the last check on the server side and returns these historical
values on the next check so that the velocity can be calculated. If no value is
given for C<--delta>, no normalization is used. In the example above, without a
normalization value of 60, a CRITICAL is returned if the number of threads
created increased more than 5 between two checks.
C<--delta> doesn't work yet with C<--base> (e.g. incremental mode for
relative checks is not available).
=head2 String checks
In addition to standard numerical checks, direct string comparison can be
used. This mode is switched on either explicitely via C<--string>
(configuration: C<String>) or by default implicitely if a heuristics determines
that a value is non-numeric. Numeric checking can be enforced with the option
C<--numeric> (configuration: Numeric).
For string checks, C<--critical> and C<--warning> are not
treated as numerical values but as string types. They are compared literally
against the value retrieved and yield the corresponding Nagios status if
matched. If the threshold is given with a leading C<!>, the condition is
negated. E.g. a C<--critical '!Running'> returns C<CRITICAL> if the value
I<not> equals to C<Running>. Alternatively you can also use a regular
expression by using C<qr/.../> as threshold value (substitute C<...> with the
pattern to used for comparison). Boolean values are returned as C<true> or
C<false> strings from the agent, so you can check for them as well with this
kind of string comparison.
No performance data will be generated for string checks by default. This
can be switched on by providing C<--perfdata on> (or "C<PerfData on>" in
the configuration). However, this probably doesn't make much sense, though.
=head2 Output Tuning
The output of C<check_jmx4perl> can be highly customized. A unit-of-measurement
can be provided with the option C<--unit> (configuration: C<Unit>) which
specifies how the the attribute or an operation's return value should be
interpreted. The units available are
B - Byte
KB - Kilo Byte
MB - Mega Byte
GB - Giga Byte
TB - Terra Byte
us - Microseconds
ms - Milliseconds
s - Seconds
m - Minutes
h - Hours
d - Days
The unit will be used for performance data as well as for the plugin's
output. Large numbers are converted to larger units automatically (and reverse
for small number that are smaller than 1). E.g. C<2048 KB> is converted to C<2
MB>. Beautifying by conversion is I<only> performed for the plugin
output, B<not> for the performance data for which no conversions happens at
all.
Beside unit handling, you can provide your own label for the Nagios output via
C<--label>. The provided option is interpreted as a pattern with the following
placeholders:
%v the absolute value
%f the absolute value as floating point number
%r the relative value for relative calculations (--base)
%u the value's unit for the output when --unit is used (after shortening)
%w the base value's unit for the output when --unit is used (after shortening)
%b the absolut base value as it is used with --base
%c the Nagios exit code in the Form "OK", "WARNING", "CRITICAL"
or "UNKNOWN"
%t Threshold value which failed ("" when the check doesn't fail)
%n name, either calulated automatically or given with --name
%d the delta value used for normalization when using incremental mode
%y WARNING threshold as configured
%z CRITICAL threshold as configured
Note that C<%u> and C<%w> are typically I<not> the same as the C<--unit>
option. They specify the unit I<after> the conversion for the plugin output as
described above. You can use the same length modifiers as for C<sprintf> to
fine tune the output.
Example:
check_jmx4perl --url http://localhost:8888/jolokia \
--alias MEMORY_HEAP_USED \
--base MEMORY_HEAP_MAX \
--critical :80 \
--label "Heap-Memory: %.2r% used (%.2v %u / %.2b %w)" \
--unit B
will result in an output like
OK - Heap-Memory: 3.48% used (17.68 MB / 508.06 MB) | '[MEMORY_HEAP_USED]'=3.48%;;:80
=head2 Security
Since the jolokia-agent is usually a simple war-file, it can be secured as any
other Java Webapplication. Since setting up authentication is JEE Server
specific, a detailed instruction is beyond the scope of this document. Please
refer to your appserver documentation, how to do this. At the moment,
C<check_jmx4perl> can use Basic-Authentication for authentication purposes
only.
In addition to this user/password authentication, the jolokia-agent uses a policy
file for fine granular access control. The policy is defined with an XML file
packaged within the agent. In order to adapt this to your needs, you need to
extract the war file, edit it, and repackage the agent with a policy file. A
future version of jmx4perl might provide a more flexible way for changing the
policy.
In detail, the following steps are required:
=over
=item *
Download F<jolokia.war> and a sample policy file F<jolokia-access.xml> into a
temporary directory:
$ jolokia
$ jolokia --policy
=item *
Edit the policy according to your needs.
$ vi jolokia-access.xml
=item *
Repackage the war file
$ jolokia repack --policy jolokia.war
=item *
Deploy the agent F<jolokia.war> as usual
=back
The downloaded sample policy file F<jolokia-access.xml> contains inline
documentation and examples, so you can easily adapt it to your environment.
Restrictions can be set to on various parameters :
=head3 Client IP address
Access to the jolokia-agent can be restricted based on the client IP accessing the
agent. A single host, either with hostname or IP address can be set or even a
complete subnet.
Example:
<remote>
<host>127.0.0.1</host>
<host>10.0.0.0/16</host>
</remote>
Only the localhost or any host in the subnet 10.0 is allowed to access the
agent. If the C<E<lt>remoteE<gt>> section is missing, access from all hosts
is allowed.
=head3 Commands
The access can be restricted to certain commands.
Example:
<commands>
<command>read</command>
</commands>
This will only allow reading of attributes, but no other operation like
execution of operations. If the C<E<lt>commandsE<gt>> section is missing, any
command is allowed. The commands known are
=over
=item read
Read an attribute
=item write
Write an attribute (used by C<check_jmx4perl> only when using incremental checks)
=item exec
Execution of an operation
=item list
List all MBeans (not used by C<check_jmx4perl>)
=item version
Version command (not used by C<check_jmx4perl>)
=item search
Search for MBean (not used by C<check_jmx4perl>)
=back
=head3 Specific MBeans
The most specific policy can be put on the MBeans themselves. For this, two
sections can be defined, depending on whether a command is globaly enabled or
denied.
=over
=item <allow>
The C<E<lt>allowE<gt>> section is used to switch on access for operations and
attributes in case C<read>, C<write> or C<exec> are globally disabled (see
above). Wildcards can be used for MBean names and attributes/and operations.
Example:
<allow>
<mbean>
<name>jolokia:*</name>
<operation>*</operation>
<attribute>*</attribute>
</mbean>
<mbean>
<name>java.lang:type=Threading</name>
<operation>findDeadlockedThreads</operation>
</mbean>
<mbean>
<name>java.lang:type=Memory</name>
<attribute mode="read">Verbose</attribute>
</mbean>
</allow>
This will allow access to all operation and attributes of all MBeans in
the C<jolokia:> domain and to the operation C<findDeadlockedThreads> on the
MBean C<java.lang:type=Threading> regardless whether the C<read> or C<exec>
command is enabled globally. The attribute C<Verbose> on
C<java.lang:type=Memory> is allowed to be read, but cannot be written (if the
C<mode> attribute is not given, both read and write is allowed by default).
=item <deny>
The C<E<lt>denyE<gt>> section forbids access to certain MBean's operation
and/or attributes, even when the command is allowed globally.
Example:
<deny>
<mbean>
<!-- Exposes user/password of data source, so we forbid this one -->
<name>com.mchange.v2.c3p0:type=PooledDataSource*</name>
<attribute>properties</attribute>
</mbean>
</deny>
This will forbid the access to the specified attribute, even if C<read> is allowed globally.
If there is an overlap between <allow> and <deny>, <allow> takes precedence.
=back
=head2 Proxy mode
C<check_jmx4perl> can be used in an I<agentless mode> as well, i.e. no
jolokia-agent needs to deployed on the target server. The setup for the agentless
mode is a bit more complicated, though:
=over
=item *
The target server needs to export its MBeans via JSR-160. The configuration for
JMX export is different for different JEE Server. L<http://labs.consol.de> has
some cooking recipes for various servers (JBoss, Weblogic).
=item *
A dedicated I<proxy server> needs to be setup on which the F<jolokia.war>
gets deployed. This can be a simple Tomcat or Jetty servlet container. Of
course, an already existing JEE Server can be used as proxy server as well.
=item *
For using C<check_jmx4perl> the target JMX URL for accessing the target server
is required. This URL typically looks like
service:jmx:rmi:///jndi/rmi://host:9999/jmxrmi
but this depends on the server to monitor. Please refer to your JEE server's
documentation for how the export JMX URL looks like.
=item *
C<check_jmx4perl> uses the proxy mody if the option C<--target> (configuration:
<Target>) is provided. In this case, this Nagios plugin contacts the proxy
server specified as usual with C<--url> (config: Url in Server section) and put
the URL specified with C<--target> in the request. The agent in the proxy then
dispatches this request to the real target and uses the JMX procotol specified
with in the target URL. The answer received is then translated into a JSON
response which is returned to C<check_jmx4perl>.
Example:
check_jmx4perl --url http://proxy:8080/jolokia \
--target service:jmx:rmi:///jndi/rmi://jeeserver:9999/jmxrmi
--alias MEMORY_HEAP_USED
--base MEMORY_HEAP_MAX
--critical 90
Here the host I<proxy> is listening on port 8080 for jolokia requests and host I<jeeserver>
exports its JMX data via JSR-160 over port 9999. (BTW, I<proxy> can be
monitored itself as usual).
So, what mode is more appropriate ? Both, the I<agent mode> and the
I<proxy mode> have advantages and disadvantages.
=back
=head3 Advantages
=over
=item *
No agent needs to be installed on the target server. This might be useful for
policy reasons.
=item *
Compared to other Nagios JMX plugin's no JVM startup is required since the
proxy server is already running.
=back
=head3 Disadvantages
=over
=item *
It takes two hops to get to the target server
=item *
Exporting JMX via JSR-160 is often not that easy as it may seem. (See post
series on remote JMX on labs.consol.de)
=item *
Some features like merging of MBean Servers are not available in proxy mode. (i.e
you need to know in advance which MBean-Server on the target you want to
contact for a certain MBean, since this information is part of the JMX URL)
=item *
Bulk request needs to be detangled into multiple JMX request since JSR-160
doesn't know anything about bulk requests.
=item *
jmx4perl's fine granular security policy is not available, since JSR-160 JMX is
an all-or-nothing thing. (except you are willing to dive deep into Java
Security stuff)
=item *
For JSR-160 objects to be transferable to the proxy, the proxy needs to know
about the Java types and those types must be serializable. If this is not the
case, the proxy isn't able to collect the information from the target. So only
a subset of MBeans can be monitored this way.
The agent protocol is more flexible since it translates the data into a JSON
structure I<before> putting it on the wire.
=back
To summarize, I would always recommend the I<agent mode> over the I<proxy mode>
except when an agentless operation is required (e.g. for policy reasons).
=head1 COMMAND LINE
The pure command line interface (without a configuration file) is mostly suited
for simple checks where the predefined defaults are suitable. For all other use
cases, a L<configuration|/"CONFIGURATION"> file fits better.
C<check_jmx4perl> knows about the following command line options:
=over
=item --url (-u)
The URL for accessing the target server (or the jolokia-proxy server, see L</"Proxy Mode">
for details about the JMX proxy mode)
Example:
--url http://localhost:8080/jolokia
=item --mbean (-m)
Object name of MBean to access
Example:
--mbean java.lang:type=Runtime
=item --attribute (-a)
A MBean's attribute name. The value of this attribute is used for threshold
checking.
Example:
--attribute Uptime
=item --operation (-o)
A MBean's operation name. The operation gets executed on the server side and
the return value is used for threshold checking. Any arguments required for
this operation has to be given as additional arguments to
C<check_jmx4perl>. See L</"Attributes and Operations"> for details.
Example:
check_jmx4perl ... --mbean java.lang:type=Threading \
--operation getThreadUserTime 1
Operation C<getThreadUserTime> takes a single argument the thread id (a long)
which is given as extra argument.
=item --path (-p)
Path for extracting an inner element from an attribute or operation return
value. See L</"Paths"> for details about paths.
Example:
--path used
=item --value
Shortcut for giving C<--mbean>, C<--attribute> and C<--path> at once.
Example:
--value java.lang:type=Memory/HeapMemoryUsage/used
Any slash (/) in the MBean name must be escaped with a backslash
(\/). Backslashes in names has to be escaped as \\.
=item --base (-b)
Switches on relative checking. The value given points to an attribute which
should be used as base value and has to be given in the shortcut notation
described above. Alternatively, the value can be an absolute number or an alias
name (L</"Aliases">) The threshold are the interpreted as relative values in
the range [0,100]. See L</"Relative Checks"> for details.
Example:
--base 100000
--base java.lang:type=Memory/HeapMemoryUsage/max
--base MEMORY_HEAP_MAX
=item --delta (-d)
Switches on incremental checking, i.e. the increase rate (or velocity) of an
attribute or operation return value is measured. The value given here is used
for normalization (in seconds). E.g. C<--delta 60> normalizes the velocity to
'growth per minute'. See L</"Incremental Checks"> for details.
=item --string
Forces string checking, in which case the threshold values are compared as
strings against the measured values. See L</"String checks"> for more
details. By default, a heuristic based on the measured value is applied to
determine, whether numerical or string checking should be use
Example:
--string --critical '!Running'
=item --numeric
Forces numeric checking, in which case the measured valued are compared against
the given thresholds according to the Nagios developer guideline specification
(L<http://nagiosplug.sourceforge.net/developer-guidelines.html#THRESHOLDFORMAT>)
Example:
--numeric --critical ~:80
=item --null
The value to be used in case the attribute or the operation's return value is
C<null>. This is useful when doing string checks. By default, this value is
"C<null>".
Example:
--null "no deadlock" --string --critical "!no deadlock"
=item --name (-n)
Name to be used for the performance data. By default a name is calculated based
on the MBean's name and the attribute/operation to monitor.
Example:
--name "HeapMemoryUsage"
=item --label (-l)
Label for using in the plugin output which can be a format specifier as
described in L</"Output Tuning">.
Example:
--label "%.2r% used (%.2v %u / %.2b %w)"
=item --perfdata
Switch off ("off") or on ("on") performance data generation. Performance data
is generated by default for numerical checks and omitted for string based
checks. For relative checks, if the value is '%' then performance data is
appended as relative values instead of absolute values.
=item --unit
Natural unit of the value measured. E.g. when measuring memory, then the memory
MXBean exports this number as bytes. The value given here is used for
shortening the value's output by converting to the largest possible unit. See
L</"Output Tuning"> for details.
Example:
--alias MEMORY_HEAP_USED --unit B
=item --critical (-c)
Critical threshold. For string checks, see L<"String checks"> for how the
critical value is interpreted. For other checks, the value given here should
conform to the specification defined in
L<http://nagiosplug.sourceforge.net/developer-guidelines.html#THRESHOLDFORMAT>.
Example:
--critical :90
=item --warning (-w)
Warning threshold, which is interpreted the same way as the C<--critical>
threshold (see above). At least a warning or critical threshold must be given.
=item --alias
An alias is a shortcut for an MBean attribute or operation. See L</"Aliases">
for details.
Example:
--alias RUNTIME_UPTIME
=item --product
When aliasing is used, C<check_jmx4perl> needs to known about the target server
type for resolving the alias. By default it used an autodetection facility,
which at least required an additional request. To avoid this, the product can
be explicitely specified here
Example:
--product jboss
=item --user, --password
User and password needed when the agent is secured with Basic
Authentication. By default, no authentication is used.
=item --timeout (-t)
How long to wait for an answer from the agent at most (in seconds). By default,
the timeout is 180s.
=item --method
The HTTP metod to use for sending the jmx4perl request. This can be either
C<get> or C<post>. By default, an method is determined automatically. C<get>
for simple, single requests, C<post> for bulk request or requests using a JMX
proxy.
=item --proxy
A HTTP proxy server to use for accessing the jolokia-agent.
Example:
--proxy http://proxyhost:8001/
=item --legacy-escape
When the deployed Jolokia agent's version is less than 1.0, then this option
should be used since the escape scheme as changed since version 1.0. This
option is only important for MBeans whose names contain slashes. It is
recommended to upgrade the agent to a post 1.0 version, though.
=item --target, --target-user, --target-password
Switches on jolokia-proxy mode and specifies the URL for accessing the target
platform. Optionally, user and password for accessing the target can be given,
too. See L</"Proxy Mode"> for details.
Example:
--target service:jmx:rmi:///jndi/rmi://bhut:9999/jmxrmi
=item --config
Specifies a configuration file from where server and check definitions can be
obtained. See L</"CONFIGURATION"> for details about the configuration file's
format.
Example:
--config /etc/jmx4perl/tomcat.cfg
=item --server
Specify a symbolic name for a server connection. This name is used to lookup a
server in the configuration file specified with C<--config>
Example:
servers.cfg:
<Server tomcat>
Url http://localhost:8080/jolokia
User roland
Password fcn
</Server>
--config /etc/jmx4perl/servers.cfg --server tomcat
See L</"CONFIGURATION"> for more about server definitions.
=item --check
The name of the check to use as defined in the configuration file. See
L</"CONFIGURATION"> about the syntax for defining checks and multi checks.
Additional arguments for parameterized checks should be given as additional
arguments on the command line. Please note, that checks specified with
C<--check> have precedence before checks defined explicitely on the command
line.
Example:
--config /etc/jmx4perl/tomcat.cfg --check tc_servlet_requests jolokia-agent
=item --version
Prints out the version of this plugin
=item --verbose (-v)
Enables verbose output during the check, which is useful for debugging. Don't
use it in production, it will confuse Nagios.
=item --doc, --help (-h), --usage (-?)
C<--usage> give a short synopsis, C<--help> prints out a bit longe usage
information.
C<--doc> prints out this man page. If an argument is given, it will only print
out the relevant sections. The following sections are recognized:
=over
=item tutorial
A 5 minute quickstart
=item reference
Reference manual explaining the various operational modes.
=item options
Command line options available for C<check_jmx4perl>
=item config
Documentation for the configuration syntax
=back
=back
=head1 CONFIGURATION
Using C<check_jmx4perl> with a configuration file is the most powerful way for
defining Nagios checks. A simple configuration file looks like
# Define server connection parameters
<Server tomcat>
Url = http://localhost:8080/jolokia
</Server>
# A simple heap memory check with a critical threshold of
# 90% of the maximal heap memory.
<Check memory_heap>
Value = java.lang:type=Memory/HeapMemoryUsage/used
Base = java.lang:type=Memory/HeapMemoryUsage/max
Unit = B
Label = Heap-Memory: %.2r% used (%.2v %u / %.2b %u)
Name = Heap
Critical = 90
</Check>
A configuration file is provided on the command line with the option
C<--config>. It can be divided into two parts: A section defining server
connection parameters and a section defining the checks themselves.
=head2 <Server>
With C<E<lt>Server I<name>E<gt>> the connection parameters for a specific
server is defined. In order to select a server the C<--server I<name>> command
line option has to be used. Within a C<E<lt>ServerE<gt>> configuration element,
the following keys can be used:
=over
=item Url
The URL under which the jolokia agent can be reached.
=item User, Password
If authentication is switched on, the user and the credentials can be provided
with the B<User> and B<Password> directive, respectively. Currently only Basic
Authentication is supported.
=item Product
The type of application server to monitor. This configuration can speed up
checks significantly, but only when aliases are used. By default when using
aliases, C<check_jmx4perl> uses autodetection for determine the target's
platform. This results in at least one additional HTTP-Request. This
configuration does not has any effect when MBeans are always used with their
full name.
=item Proxy
A HTTP Proxy URL and credentials can be given with the C<E<lt>ProxyE<gt>>
sub-section. Example:
<Server>
....
<Proxy>
Url = http://proxy.company.com:8001
User = woody
Password = buzz
</Proxy>
</Server>
=over
=item Url
The proxy URL
=item User, Password
Optional user and credentials for accessing the proxy
=back
=item Target
With this directive, the JMX-Proxy mode can be switched on. As described in
section L</"Proxy mode">, C<check_jmx4perl> can operate in an agentless mode,
where the agent servlet is deployed only on an intermediated, so called
JMX-Proxy server, whereas the target platform only needs to export JMX
information in the traditional way (e.g. via JSR-160 export). This mode is
especially useful if the agent is not allowed to be installed on the target
platform. However, this approach has some drawbacks and some functionality is
missing there, so the agent-mode is the recommended way. A sample JMX-Proxy
configuration looks like:
<Target>
Url = service:jmx:rmi:///jndi/rmi://tessin:6666/jmxrmi
User = max
Password = frisch
</Target>
For a discussion about the advantages and disadvantages of the JMX-Proxy mode,
please have a look at L<http://labs.consol.de/> which contains some evaluations
of this mode for various application servers (e.g. JBoss and Weblogic).
=over
=item Url
The JMX-RMI Url to access the target platform.
=item User, Password
User and password for authentication against the target server.
=back
=back
=head2 Single Check
With C<E<lt>CheckE<gt>> a single check can be defined. It takes any option
available also available via the command line. Each check has a name, which can
be referenced from the commandline with the option C<--check I<name>>.
Example:
<Check memory_heap>
Value = java.lang:type=Memory/HeapMemoryUsage/used
Base = java.lang:type=Memory/HeapMemoryUsage/max
Label = Heap-Memory:
Name = Heap
Critical = 90
</Check>
The C<E<lt>CheckE<gt>> section knows about the following directives:
=over
=item Mbean
The C<ObjectName> of the MBean to monitor.
=item Attribute
Attribute to monitor.
=item Operation
Operation, whose return value should be monitored. Either C<Attribute> or
C<Operation> should be given, but not both. If the operation takes arguments,
these need to be given as additional arguments to the C<check_jmx4perl> command
line call. In the rare case, you need to call an overloaded operation (i.e. an
operation whose name exists multiple times on the same MBean but with different
parameter types), the argument types can be given within parentheses:
<Check>
....
Operation = checkUserCount(java.lang.String,java.lang.String)
...
</Check>
=item Alias
Alias, which must be known to C<check_jmx4perl>. Use C<jmx4perl aliases> to get
a list of all known aliases. If C<Alias> is given as configuration directive,
C<Operation> and/or C<Attribute> is ignored. Please note, that using C<Alias>
without C<Product> in the server section leads to at least one additional HTTP
request.
=item Path
Path to apply to the attribute or operation return value. See L</"Paths"> for
more information about paths.
=item Value
Value is a shortcut for specifying C<MBean>, C<Attribute> and C<Path> at
once. Simply concatenate all three parts via C</> (the C<Path> part is
optional). Slashes within MBean names needs to be escaped with a C<\>
(backslash). Example:
Value = java.lang:type=Memory/HeapMemoryUsage/used
is equivalent to
MBean = java.lang:type=Memory
Attribute = HeapMemoryUsage
Path = used
=item Base
Switches on relative checks. See L</"Relative Checks"> for more information
about relative checks. The value specified with this directive defines the
base value against which the relative value should be calculated. The format is
the same as for C<Value>:
Base = java.lang:type=Memory/HeapMemoryUsage/max
For relative checks, the C<Critical> and C<Warning> Threshold are interpreted
as a value between 0% and 100%.
=item BaseMBean, BaseAttribute and BasePath
As an alternative to specifying a base value in a combined fashion the
different parts can be given separately. C<BaseMBean> and C<BaseAttribute>
switches on relative checks and specifies the base value. An optional
C<BasePath> can be used to provide the path within this base value.
The example above can be also written as
BaseMBean = java.lang:type=Memory
BaseAttribute = HeapMemoryUsage
BasePath = max
=item Delta
Switches on incremental mode as described in section L</"Incremental
Checks">. The value given is used for normalization the increase rate. E.g.
Delta = 60
measures the growth rate per minute (60 seconds). If no value is given, the
absolute increase between two checks is used.
=item Numeric
This directive switches on numeric mode, i.e. the given threshold values are
compared numerically against the returned JMX value. By default, the check mode
is determined by a heuristic algorithm.
=item String
String checks, which are switched on with this directive, are useful for
non-numeric thresholds. See L</"String checks"> for more details.
=item Name
The name to be used in the performance data. By default, a name is calculated
based on the MBean and attribute/operation name.
=item Label
Format for setting the plugin output (not the performance data, use C<Name> for
this). It takes a printf like format string which is described in detail in
L</"Output Tuning">.
=item PerfData
By default, performance data is appended for numeric checks. This can be tuned
by setting this directive to "false" (or "0", "no", "off") in which case
performance data is omitted. If using this in a base check, an inherited check
can switch performance data generation back on with "true" (or "1", "yes", "on")
For relative checks, the value can be set to '%'. In this case, performance
data is added as relative values instead of the absolute value measured.
=item Unit
This specifies how the return value should be interpreted. This value, if
given, must conform to the unit returned by the JMX
attribute/operation. E.g. for C<java.lang:type=Memory/HeapMemoryUsage/used>
unit, if set, must be C<B> since this JMX call returns the used memory measured
in bytes. The value given here is only used for shortening the plugin's output
automatically. For more details and for what units are available refer to
section L</"Output Tuning">.
=item Critical
Specifies the critical threshold. If C<String> is set (or the heuristics
determines a string check), this should be a string value as described in
L</"String checks">. For relative checks, this should be a relative value in
ther range [0,100]. Otherwise, it is a simple numeric value which is used as
threshold. For numeric checks, the threshhold can be given in the format
defined at
L<http://nagiosplug.sourceforge.net/developer-guidelines.html#THRESHOLDFORMAT>.
=item Warning
Defines the warning threshold the same way as described for the C<Critical>
threshold.
=item Null
Replacement value when an attribute is null or an operation returns a null
value. This value then can be used in string checks in order to check against
null values. By default, this value is "C<null>".
=item Method
HTTP Method to use for the check. Available values are C<GET> or C<POST> for
GET or POST HTTP-Requests, respectively. By default a method is determined
automatically. The value can be given case insensitively.
=item Use
In order to use parent checks, this directive specifies the parent along with
any parameters passed through. For example,
Use = memory_relative_base(80,90),base_label
uses a parent check named C<memory_relative_base>, which must be a check
defined in the same configuration file (or an imported on). Additionally, the
parameters C<80> and C<90> are passed to this check (which can be accessed
there via the argument placeholders C<$0> and C<$1>). See L</"Parent checks">
and L</"Parameterized checks"> for more information about check inheritance.
Multiple parents can be given by providing them in a comma separated list.
=back
=head2 Includes
Checks can be organized in multiple configuration files. To include another
configuration file, the C<include> directive can be used:
include tomcat.cfg
include threads.cfg
include memory.cfg
If given as relative path, the configuration files are looked up in the same
directory as the current configuration file. Absolute paths can be given, too.
=head2 Parent checks
With C<check_jmx4perl> parent checks it is possible to define common base
checks, which are usable in various sub-checks. Any C<E<lt>CheckE<gt>> can be a
parent check as soon as it is referenced via a C<Use> directive from within
another check's definition. When a check with a parent check is used, its
configuration is merged with this from the parent check with own directives
having a higher priority. Parent checks can have parent checks as well (and so
on).
For example, consider the following configuration:
<Check grand_parent>
Name grand_parent
Label GrandPa
Critical 10
</Check>
<Check parent_1>
Use grand_parent
Name parent_1
Critical 20
</Check>
<Check parent_2>
Name parent_2
Warning 20
</Check>
<Check check>
Use parent_1,parent_2
Warning 40
</Check>
In this scenario, when check C<check> is used, it has a C<Name> "C<parent_2>"
(last parent check in C<Use>), a C<Label> "GrandPa" (inherited from
C<grand_parent> via C<parent_1>), a C<Critical> 20 (inherited from C<parent_1>)
and a C<Warning> 40 (directly give in the check definition).
A parent value of a configuration directive can be refered to with the
placeholder C<$BASE>. For example:
<Check parent>
Name Parent
</Check>
<Check check>
Use parent
Name Child: $BASE
</Check>
This will lead to a C<Name> "C<Child: Parent>" since C<$BASE> is resolved to
the parent checks valus of C<Name>, C<"Parent"> in this case. The base value is
searched upwards in the inheritance hierarchy (parent, grand parent, ...) until
a value is found. If nonen is found, an empty string is used for C<$BASE>.
=head2 Parameterized checks
Checks can be parameterized, i.e. they can take arguments which are replaced in
the configuration during runtime. Arguments are used in check definition via
the positional format C<$0>, C<$1>, .... (e.g. C<$0> is the first argument
given). Arguments can either be given on the command line as extra arguments to
C<check_jmx4perl> or within the C<Use> directive to provide arguments to parent
checks.
Example:
<Check parent>
Name $0
Label $1
</Check>
<Check child_check>
Use parent($0,"Check-Label")
....
</Check>
$ check_jmx4perl --check child_check .... "Argument-Name"
OK - Check-Label | 'Argument-Name'= ....
As it can be seen in this example, arguments can be propagated to a parent
check. In this case, C<$0> from the command line (C<Argument-Name>) is passed
through to the parent check which uses it in the C<Name> directive. C<$1> from
the parent check is replaced with the value "C<Check-Label>" given in the
C<Use> directive of the child check.
Parameters can have default values. These default values are taken in case an
argument is missing (either when declaring the parent check or missing from the
command line). Default values are specified with
C<${>I<arg-nr>C<:>I<default>C<}>. For example,
<Check relative_base>
Label = %.2r% used (%.2v %u / %.2b %w)
Critical = ${0:90}
Warning = ${1:80}
</Check>
defines a default value of 90% for the critical threshold and 80% for the
warning threshold. If a child check uses this parent definition and only wants
to ommit the first parameter (but explicitely specifying the second parameter)
it can do so by leaving the first parameter empty:
<Check child>
Use relative_base(,70)
</Check>
=head2 Multichecks
Multiple checks can be combined to a single I<MultiCheck>. The advantage of a
multi check is, that multiple values can be retrieved from the server side with
a single HTTP request. The output is conformant to Nagios 3 multiline
format. It will lead to a C<CRITICAL> value as soon as one check is critical,
same for C<WARNING>. If both, C<CRITICAL> and C<WARNING> is triggered by two or
more checks, then a C<CRITICAL> is taken.
A multi-check can be defined with the directive C<E<lt>MultiCheckE<gt>>, which
contain various references to other C<E<lt>CheckE<gt>> definitions or other
multi check definitions.
Example:
<MultiCheck all>
MultiCheck memory
MultiCheck threads
</MultiCheck>
<MultiCheck memory>
Check memory_heap($0,80)
Check memory_pool_base("CMS Perm Gen",90,80)
</MultiCheck>
<MultiCheck threads>
Check thread_inc
Check thread_deadlock
</MultiCheck>
Here a multi check group I<memory> has been defined with reference to two
checks, which must exist somewhere else in the configuration file. As it can be
seen, parameters can be given through to the check in the usual way (literally
or with references to command line arguments). The group I<all> combines the
two groups I<memory> and I<thread>, containing effectively four checks.
A multi-check is referenced from the command line like any other check:
$ check_jmx4perl .... --check all 90
(90 is the argument which replaces C<$0> in the definition above).
=head2 Predefined checks
C<check_jmx4perl> comes with a collection of predefined configuration for
various application servers. The configurations can be found in the directory
F<config> within the toplevel distribution directory. The configurations are
fairly well documented inline.
=head3 common.cfg
Common check definitions, which can be used as parents for own checks. E.g. a
check C<relative_base> can be used as parent for getting a nicely formatted
output message.
=head3 memory.cfg
Memory checks for heap and non-heap memoy as well as for various memory
pools. Particularly interesting here is the so called I<Perm Gen> pool as it
holds the java type information which can overflow e.g after multiple
redeployments when the old classloader of the webapp can't be cleared up by the
garbage collector (someone might still hold a reference to it).
=head3 threads.cfg
Checks for threads, i.e. checking for the tread count increase rate. A check
for finding out deadlocks (on a JDK 6 VM) is provided, too.
=head3 jetty.cfg
Various checks for jetty like checking for running servlets, thread count within
the app server, sessions (number and lifing time) or requests per minute.
=head3 tomcat.cfg
Mostly the same checks as for jetty, but for tomcat as application server.
=head1 LICENSE
This file is part of jmx4perl.
Jmx4perl is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
jmx4perl is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with jmx4perl. If not, see <http://www.gnu.org/licenses/>.
=head1 AUTHOR
roland@cpan.org
=cut
1;