Steven Haryanto > Log-Any-App-0.46 > Log::Any::App

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Module Version: 0.46   Source   Latest Release: Log-Any-App-0.47

NAME ^

Log::Any::App - An easy way to use Log::Any in applications

VERSION ^

This document describes version 0.46 of Log::Any::App (from Perl distribution Log-Any-App), released on 2014-07-06.

SYNOPSIS ^

Most of the time you only need to do this:

 # in your script.pl
 use Log::Any::App '$log';
 $log->warn("blah ...");
 if ($log->is_debug) { ... }

 # or, in command line
 % perl -MLog::Any::App -MModuleThatUsesLogAny -e'...'

Here's the default logging that Log::Any::App sets up for you:

 Condition                        screen  file               syslog        dir
 --------------------------------+-------+------------------+-------------+---
 -e (one-liners)                  y       -                  -             -
 Scripts running as normal user   y       ~/NAME.log         -             -
 Scripts running as root          y       /var/log/NAME.log  -             -
 Daemons                          -       y                  y             -

You can customize level from outside the script, using environment variables or command-line options (won't interfere with command-line processing modules like Getopt::Long etc):

 % DEBUG=1 script.pl
 % LOG_LEVEL=trace script.pl
 % script.pl --verbose

And to customize other stuffs:

 use Log::Any::App '$log',
     -syslog => 1, # turn on syslog logging explicitly
     -screen => 0, # turn off screen logging explicitly
     -file   => {path=>'/foo/bar', max_size=>'10M', histories=>10};
                # customize file logging

For more customization like categories, per-category level, per-output level, multiple outputs, string patterns, etc see "USING AND EXAMPLES" and init().

DESCRIPTION ^

IMPORTANT: Please read "ROAD TO 1.0" on some incompatibilities in the near future, before 1.0 is released.

Log::Any::App is a convenient combo for Log::Any and Log::Log4perl (although alternative backends beside Log4perl might be considered in the future). To use Log::Any::App you need to be sold on the idea of Log::Any first, so please do a read up on that first.

The goal of Log::Any::App is to provide developers an easy and concise way to add logging to their *applications*. That is, instead of modules; modules remain using Log::Any to produce logs. Applications can upgrade to full Log4perl later when necessary, although in my experience, they usually don't.

With Log::Any::App, you can replace this code in your application:

 use Log::Any '$log';
 use Log::Any::Adapter;
 use Log::Log4perl;
 my $log4perl_config = '
   some
   long
   multiline
   config...';
 Log::Log4perl->init(\$log4perl_config);
 Log::Any::Adapter->set('Log4perl');

with just this:

 use Log::Any::App '$log'; # plus some other options when necessary

Most of the time you don't need to configure anything as Log::Any::App will construct the most appropriate default Log4perl configuration for your application.

USING AND EXAMPLES ^

To use Log::Any::App, just do:

 use Log::Any::App '$log';

or from the command line:

 % perl -MLog::Any::App -MModuleThatUsesLogAny -e ...

This will send logs to screen as well as file (unless -e scripts, which only log to screen). Default log file is ~/$SCRIPT_NAME.log, or /var/log/$SCRIPT_NAME.log if script is running as root. Default level is 'warn'.

The 'use Log::Any::App' statement can be issued before or after the modules that use Log::Any, it doesn't matter. Logging will be initialized in the INIT phase by Log::Any::App.

You are not required to import '$log', and don't need to if you do not produce logs in your application (only in the modules).

Changing logging level

Since one of the most commonly tweaked logging setting is level (for example: increasing level when debugging problems), Log::Any::App provides several mechanisms to change log level, either from the script or from outside the script, for your convenience. Below are the mechanisms, ordered from highest priority:

These mechanisms are explained in more details in the documentation for the init() function. But below are some examples.

To change level from inside the script:

 use Log::Any::App '$log', -level => 'debug';

This is useful if you want a fixed level that cannot be overridden by other mechanisms (since setting level using import argument has the highest priority). But oftentimes what you want is changing level without modifying the script itself. Thereby, just write:

 use Log::Any::App '$log';

and then you can use environment variables to change level:

 TRACE=1 script.pl;         # setting level to trace
 DEBUG=1 script.pl;         # setting level to debug
 VERBOSE=1 script.pl;       # setting level to info
 QUIET=1 script.pl;         # setting level to error
 LOG_LEVEL=trace script.pl; # setting a specific log level

or command-line options:

 script.pl --trace
 script.pl --debug
 script.pl --verbose
 script.pl --quiet
 script.pl --log_level=debug;   # '--log-level debug' will also do

Regarding command-line options: Log::Any::App won't consume the command-line options from @ARGV and thus won't interfere with command-line processing modules like Getopt::Long or App::Options. If you use a command-line processing module and plan to use command-line options to set level, you might want to define these level options, or your command-line processing module will complain about unknown options.

Changing default level

The default log level is 'warn'. To change the default level, you can use 'main' package variables (since they have the lowest priority):

 use Log::Any::App '$log';
 BEGIN { our $Log_Level = 'info' } # be more verbose by default

Then you will still be able to use level flag files or environment variables or command-line options to override this setting.

Changing per-output level

Logging level can also be specified on a per-output level. For example, if you want your script to be chatty on the screen but still logs to file at the default 'warn' level:

 SCREEN_VERBOSE=1 script.pl
 SCREEN_DEBUG=1 script.pl
 SCREEN_TRACE=1 script.pl
 SCREEN_LOG_LEVEL=info script.pl

 script.pl --screen_verbose
 script.pl --screen-debug
 script.pl --screen-trace=1
 script.pl --screen-log-level=info

Similarly, to set only file level, use FILE_VERBOSE, FILE_LOG_LEVEL, --file-trace, and so on.

Setting default per-output level

As with setting default level, you can also set default level on a per-output basis:

 use Log::Any::App '$log';
 BEGIN {
     our $Screen_Log_Level = 'off';
     our $File_Quiet = 1; # setting file level to 'error'
     # and so on
 }

If a per-output level is not specified, it will default to the general log level.

Enabling/disabling output

To disable a certain output, you can do this:

 use Log::Any::App '$log', -file => 0;

or:

 use Log::Any::App '$log', -screen => {level=>'off'};

and this won't allow the output to be re-enabled from outside the script. However if you do this:

 use Log::Any::App;
 BEGIN { our $Screen_Log_Level = 'off' }

then by default screen logging is turned off but you will be able to override the screen log level using level flag files or environment variables or command-line options (SCREEN_DEBUG, --screen-verbose, and so on).

Changing log level of cron scripts

Environment variables and command-line options allow changing log level without modifying the script. But for scripts specified in crontab, they still require changing crontab entries, e.g.:

 # turn on debugging
 */5 * * * * DEBUG=1 foo

 # be silent
 */5 * * * * bar --quiet

Another mechanism, level flag file, is useful in this case. By doing:

 $ echo debug > ~/foo.log_level
 # touch /etc/bar.QUIET

you can also change log levels without modifying your crontab.

Changing log file name/location

By default Log::Any::App will log to file to ~/$NAME.log (or /var/log/$NAME.log if script is running as root), where $NAME is taken from the basename of $0. But this can be changed using:

 use Log::Any::App '$log', -name => 'myprog';

Or, using custom path:

 use Log::Any::App '$log', -file => '/path/to/file';

Changing other output parameters

Each output argument can accept a hashref to specify various options. For example:

 use Log::Any::App '$log',
     -screen => {color=>0},   # never use color
     -file   => {path=>'/var/log/foo',
                 max_size=>'10M',
                 histories=>10,
                },

For all the available options of each output, see the init() function.

Logging to syslog

Logging to syslog is enabled by default if your script looks like or declare that it is a daemon, e.g.:

 use Net::Daemon; # this indicate your program is a daemon
 use Log::Any::App; # syslog logging will be turned on by default

 use Log::Any::App -daemon => 1; # script declares that it is a daemon

 # idem
 package main;
 our $IS_DAEMON = 1;

But if you are certain you don't want syslog logging:

 use Log::Any::App -syslog => 0;

Logging to directory

This is done using Log::Dispatch::Dir where each log message is logged to a different file in a specified directory. By default logging to dir is not turned on, to turn it on:

 use Log::Any::App '$log', -dir => 1;

For all the available options of directory output, see the init() function.

Multiple outputs

Each output argument can accept an arrayref to specify more than one output. For example below is a code to log to three files:

 use Log::Any::App '$log',
     -file => [1, # default, to ~/$NAME.log or /var/log/$NAME.log
               "/var/log/log1",
               {path=>"/var/log/debug_foo", category=>'Foo', level=>'debug'}];

Changing level of certain module(s)

Suppose you want to shut up logs from modules Foo, Bar::Baz, and Qux (and their submodules as well, e.g. Foo::Alpha, Bar::Baz::Beta::Gamma) because they are too noisy:

 use Log::Any::App '$log',
     -category_level => { Foo => 'off', 'Bar::Baz' => 'off', Qux => 'off' };

or (same thing):

 use Log::Any::App '$log',
     -category_alias => { -noisy => [qw/Foo Bar::Baz Qux/] },
     -category_level => { -noisy => 'off' };

You can even specify this on a per-output basis. Suppose you only want to shut up the noisy modules on the screen, but not on the file:

 use Log::Any::App '$log',
    -category_alias => { -noisy => [qw/Foo Bar::Baz Qux/] },
    -screen => { category_level => { -noisy => 'off' } };

Or perhaps, you want to shut up the noisy modules everywhere, except on the screen:

 use Log::Any::App '$log',
     -category_alias => { -noisy => [qw/Foo Bar::Baz Qux/] },
     -category_level => { -noisy => 'off' },
     -syslog => 1,                        # uses general -category_level
     -file   => "/var/log/foo",           # uses general -category_level
     -screen => { category_level => {} }; # overrides general -category_level

You can also do this from the outside the script using environment variable, which is more flexible. Encode data structure using JSON:

 % LOG_SHOW_CATEGORY=1 \
   LOG_CATEGORY_ALIAS='{"-noisy":["Foo","Bar::Baz","Quz"]}' \
   LOG_CATEGORY_LEVEL='{"-noisy":"off"}' script.pl ...

Only displaying log from certain module(s)

Use a combination of LOG_LEVEL and LOG_CATEGORY_LEVEL. For example:

 % LOG_LEVEL=off LOG_CATEGORY_LEVEL='{"Foo.Bar":"trace", "Baz":"info"}' \
   script.pl ...

Displaying category name

 % LOG_SHOW_CATEGORY=1 script.pl ...

Now instead of:

 [25] Starting baz ritual ...

now log messages will be prefixed with category:

 [cat Foo.Bar][25] Starting baz ritual ...

Displaying location name

 % LOG_SHOW_LOCATION=1 script.pl ...

Now log messages will be prefixed with location (function/file/line number) information:

 [loc Foo::Bar lib/Foo/Bar.pm (12)][25] Starting baz ritual ...

Preventing logging level to be changed from outside the script

Sometimes, for security/audit reasons, you don't want to allow script caller to change logging level. As explained previously, you can use the 'level' import argument (the highest priority of level-setting):

 use Log::Any::App '$log', -level => 'debug'; # always use debug level

TODO: Allow something like 'debug+' to allow other mechanisms to *increase* the level but not decrease it. Or 'debug-' to allow other mechanisms to decrease level but not increase it. And finally 'debug,trace' to specify allowable levels (is this necessary?)

Debugging

To see the Log4perl configuration that is generated by Log::Any::App and how it came to be, set environment LOGANYAPP_DEBUG to true.

FUNCTIONS ^

None is exported.

init(\@args)

This is the actual function that implements the setup and configuration of logging. You normally need not call this function explicitly (but see below), it will be called once in an INIT block. In fact, when you do:

 use Log::Any::App 'a', 'b', 'c';

it is actually passed as:

 init(['a', 'b', 'c']);

You will need to call init() manually if you require Log::Any::App at runtime, in which case it is too late to run INIT block. If you want to run Log::Any::App in runtime phase, do this:

 require Log::Any::App;
 Log::Any::App::init(['a', 'b', 'c']);

Arguments to init can be one or more of:

-log => BOOL

Whether to do log at all. Default is from LOG environment variable, or 1. This option is only to allow users to disable Log::Any::App (thus speeding up startup by avoiding loading Log4perl, etc) by passing LOG=1 environment when running programs. However, if you explicitly set this option to 1, Log::Any::App cannot be disabled this way.

-init => BOOL

Whether to call Log::Log4perl->init() after setting up the Log4perl configuration. Default is true. You can set this to false, and you can initialize Log4perl yourself (but then there's not much point in using this module, right?)

-name => STRING

Change the program name. Default is taken from $0.

-level_flag_paths => ARRAY OF STRING

Edit level flag file locations. The default is [$homedir, "/etc"].

-daemon => BOOL

Declare that script is a daemon. Default is no. Aside from this, to declare that your script is a daemon you can also set $main::IS_DAEMON to true.

-category_alias => {ALIAS=>CATEGORY, ...}

Create category aliases so the ALIAS can be used in place of real categories in each output's category specification. For example, instead of doing this:

 init(
     -file   => [category=>[qw/Foo Bar Baz/], ...],
     -screen => [category=>[qw/Foo Bar Baz/]],
 );

you can do this instead:

 init(
     -category_alias => {-fbb => [qw/Foo Bar Baz/]},
     -file   => [category=>'-fbb', ...],
     -screen => [category=>'-fbb', ...],
 );

You can also specify this from the environment variable LOG_CATEGORY_ALIAS using JSON encoding, e.g.

 LOG_CATEGORY_ALIAS='{"-fbb":["Foo","Bar","Baz"]}'
-category_level => {CATEGORY=>LEVEL, ...}

Specify per-category level. Categories not mentioned on this will use the general level (-level). This can be used to increase or decrease logging on certain categories/modules.

You can also specify this from the environment variable LOG_CATEGORY_LEVEL using JSON encoding, e.g.

 LOG_CATEGORY_LEVEL='{"-fbb":"off"}'
-level => 'trace'|'debug'|'info'|'warn'|'error'|'fatal'|'off'

Specify log level for all outputs. Each output can override this value. The default log level is determined as follow:

Search in command-line options. If App::Options is present, these keys are checked in %App::options: log_level, trace (if true then level is trace), debug (if true then level is debug), verbose (if true then level is info), quiet (if true then level is error).

Otherwise, it will try to scrape @ARGV for the presence of --log-level, --trace, --debug, --verbose, or --quiet (this usually works because Log::Any::App does this in the INIT phase, before you call Getopt::Long's GetOptions() or the like).

Search in environment variables. Otherwise, it will look for environment variables: LOG_LEVEL, QUIET. VERBOSE, DEBUG, TRACE.

Search in level flag files. Otherwise, it will look for existence of files with one of these names $NAME.QUIET, $NAME.VERBOSE, $NAME.TRACE, $NAME.DEBUG, or content of $NAME.log_level in ~ or /etc.

Search in main package variables. Otherwise, it will try to search for package variables in the main namespace with names like $Log_Level or $LOG_LEVEL or $log_level, $Quiet or $QUIET or $quiet, $Verbose or $VERBOSE or $verbose, $Trace or $TRACE or $trace, $Debug or $DEBUG or $debug.

If everything fails, it defaults to 'warn'.

-filter_text => STR

Only show log lines matching STR. Default from LOG_FILTER_TEXT environment.

-filter_no_text => STR

Only show log lines not matching STR. Default from LOG_FILTER_NO_TEXT environment.

-filter_citext => STR

Only show log lines matching STR (case insensitive). Default from LOG_FILTER_CITEXT environment.

-filter_no_citext => STR

Only show log lines not matching STR (case insensitive). Default from LOG_FILTER_NO_CITEXT environment.

-filter_re => RE

Only show log lines matching regex pattern RE. Default from LOG_FILTER_RE environment.

-filter_no_re => RE

Only show log lines not matching regex pattern RE. Default from LOG_FILTER_NO_RE environment.

-file => 0 | 1|yes|true | PATH | {opts} | [{opts}, ...]

Specify output to one or more files, using Log::Dispatch::FileWriteRotate.

If the argument is a false boolean value, file logging will be turned off. If argument is a true value that matches /^(1|yes|true)$/i, file logging will be turned on with default path, etc. If the argument is another scalar value then it is assumed to be a path. If the argument is a hashref, then the keys of the hashref must be one of: level, path, max_size (maximum size before rotating, in bytes, 0 means unlimited or never rotate), histories (number of old files to keep, excluding the current file), suffix (will be passed to Log::Dispatch::FileWriteRotate's constructor), period (will be passed to Log::Dispatch::FileWriteRotate's constructor), buffer_size (will be passed to Log::Dispatch::FileWriteRotate's constructor), category (a string of ref to array of strings), category_level (a hashref, similar to -category_level), pattern_style (see "PATTERN STYLES"), pattern (Log4perl pattern), filter_text, filter_no_text, filter_citext, filter_no_citext, filter_re, filter_no_re.

If the argument is an arrayref, it is assumed to be specifying multiple files, with each element of the array as a hashref.

How Log::Any::App determines defaults for file logging:

If program is a one-liner script specified using "perl -e", the default is no file logging. Otherwise file logging is turned on.

If the program runs as root, the default path is /var/log/$NAME.log, where $NAME is taken from $0 (or -name). Otherwise the default path is ~/$NAME.log. Intermediate directories will be made with File::Path.

If specified path ends with a slash (e.g. "/my/log/"), it is assumed to be a directory and the final file path is directory appended with $NAME.log.

Default rotating behaviour is no rotate (max_size = 0).

Default level for file is the same as the global level set by -level. But App::options, command line, environment, level flag file, and package variables in main are also searched first (for FILE_LOG_LEVEL, FILE_TRACE, FILE_DEBUG, FILE_VERBOSE, FILE_QUIET, and the similars).

You can also specify category level from environment FILE_LOG_CATEGORY_LEVEL.

-dir => 0 | 1|yes|true | PATH | {opts} | [{opts}, ...]

Log messages using Log::Dispatch::Dir. Each message is logged into separate files in the directory. Useful for dumping content (e.g. HTML, network dumps, or temporary results).

If the argument is a false boolean value, dir logging will be turned off. If argument is a true value that matches /^(1|yes|true)$/i, dir logging will be turned on with defaults path, etc. If the argument is another scalar value then it is assumed to be a directory path. If the argument is a hashref, then the keys of the hashref must be one of: level, path, max_size (maximum total size of files before deleting older files, in bytes, 0 means unlimited), max_age (maximum age of files to keep, in seconds, undef means unlimited). histories (number of old files to keep, excluding the current file), category, category_level (a hashref, similar to -category_level), pattern_style (see "PATTERN STYLES"), pattern (Log4perl pattern), filename_pattern (pattern of file name), filter_text, filter_no_text, filter_citext, filter_no_citext, filter_re, filter_no_re.

If the argument is an arrayref, it is assumed to be specifying multiple directories, with each element of the array as a hashref.

How Log::Any::App determines defaults for dir logging:

Directory logging is by default turned off. You have to explicitly turn it on.

If the program runs as root, the default path is /var/log/$NAME/, where $NAME is taken from $0. Otherwise the default path is ~/log/$NAME/. Intermediate directories will be created with File::Path. Program name can be changed using -name.

Default rotating parameters are: histories=1000, max_size=0, max_age=undef.

Default level for dir logging is the same as the global level set by -level. But App::options, command line, environment, level flag file, and package variables in main are also searched first (for DIR_LOG_LEVEL, DIR_TRACE, DIR_DEBUG, DIR_VERBOSE, DIR_QUIET, and the similars).

You can also specify category level from environment DIR_LOG_CATEGORY_LEVEL.

-screen => 0 | 1|yes|true | {opts}

Log messages using Log::Log4perl::Appender::ScreenColoredLevels.

If the argument is a false boolean value, screen logging will be turned off. If argument is a true value that matches /^(1|yes|true)$/i, screen logging will be turned on with default settings. If the argument is a hashref, then the keys of the hashref must be one of: color (default is true, set to 0 to turn off color), stderr (default is true, set to 0 to log to stdout instead), level, category, category_level (a hashref, similar to -category_level), pattern_style (see "PATTERN STYLE"), pattern (Log4perl string pattern), filter_text, filter_no_text, filter_citext, filter_no_citext, filter_re, filter_no_re.

How Log::Any::App determines defaults for screen logging:

Screen logging is turned on by default.

Default level for screen logging is the same as the global level set by -level. But App::options, command line, environment, level flag file, and package variables in main are also searched first (for SCREEN_LOG_LEVEL, SCREEN_TRACE, SCREEN_DEBUG, SCREEN_VERBOSE, SCREEN_QUIET, and the similars).

Color can also be turned on/off using environment variable COLOR (if color argument is not set).

You can also specify category level from environment SCREEN_LOG_CATEGORY_LEVEL.

-syslog => 0 | 1|yes|true | {opts}

Log messages using Log::Dispatch::Syslog.

If the argument is a false boolean value, syslog logging will be turned off. If argument is a true value that matches /^(1|yes|true)$/i, syslog logging will be turned on with default level, ident, etc. If the argument is a hashref, then the keys of the hashref must be one of: level, ident, facility, category, category_level (a hashref, similar to -category_level), pattern_style (see "PATTERN STYLES"), pattern (Log4perl pattern), filter_text, filter_no_text, filter_citext, filter_no_citext, filter_re, filter_no_re.

How Log::Any::App determines defaults for syslog logging:

If a program is a daemon (determined by detecting modules like Net::Server or Proc::PID::File, or by checking if -daemon or $main::IS_DAEMON is true) then syslog logging is turned on by default and facility is set to daemon, otherwise the default is off.

Ident is program's name by default ($0, or -name).

Default level for syslog logging is the same as the global level set by -level. But App::options, command line, environment, level flag file, and package variables in main are also searched first (for SYSLOG_LOG_LEVEL, SYSLOG_TRACE, SYSLOG_DEBUG, SYSLOG_VERBOSE, SYSLOG_QUIET, and the similars).

You can also specify category level from environment SYSLOG_LOG_CATEGORY_LEVEL.

-unixsock => 0 | 1|yes|true | PATH | {opts} | [{opts}, ...]

Specify output to one or more existing, listening, datagram Unix domain sockets, using Log::Log4perl::Appender::Socket::UNIX.

The listening end might be a different process, or the same process using a different thread of nonblocking I/O. It usually makes little sense to make the same program the listening end. If you want, for example, to let a client connects to your program to see logs being produced, you might want to setup an in-memory output (-array) and create another thread or non-blocking I/O to listen to client requests and show them the content of the array when requested.

If the argument is a false boolean value, Unix domain socket logging will be turned off. If argument is a true value that matches /^(1|yes|true)$/i, Unix domain socket logging will be turned on with default path, etc. If the argument is another scalar value then it is assumed to be a path. If the argument is a hashref, then the keys of the hashref must be one of: level, path, filter_text, filter_no_text, filter_citext, filter_no_citext, filter_re, filter_no_re.

If the argument is an arrayref, it is assumed to be specifying multiple sockets, with each element of the array as a hashref.

How Log::Any::App determines defaults for Unix domain socket logging:

By default Unix domain socket logging is off.

If the program runs as root, the default path is /var/run/$NAME-log.sock, where $NAME is taken from $0 (or -name). Otherwise the default path is ~/$NAME-log.sock.

If specified path ends with a slash (e.g. "/my/log/"), it is assumed to be a directory and the final socket path is directory appended with $NAME-log.sock.

Default level is the same as the global level set by -level. But App::options, command line, environment, level flag file, and package variables in main are also searched first (for UNIXSOCK_LOG_LEVEL, UNIXSOCK_TRACE, UNIXSOCK_DEBUG, UNIXSOCK_VERBOSE, UNIXSOCK_QUIET, and the similars).

You can also specify category level from environment UNIXSOCK_LOG_CATEGORY_LEVEL.

-array => 0 | {opts} | [{opts}, ...]

Specify output to one or more Perl arrays. Logging will be done using Log::Dispatch::ArrayWithLimits. Note that the syntax is:

 -array => {array=>$ary}

and not just:

 -array => $ary

because that will be interpreted as multiple array outputs:

 -array => [{output1}, ...]

If the argument is a false boolean value, Unix domain socket logging will be turned off. Otherwise argument must be a hashref or an arrayref (to specify multiple outputs). If the argument is a hashref, then the keys of the hashref must be one of: level, array (defaults to new anonymous array []), filter_text, filter_no_text, filter_citext, filter_no_citext, filter_re, filter_no_re. If the argument is an arrayref, it is assumed to be specifying multiple sockets, with each element of the array as a hashref.

How Log::Any::App determines defaults for array logging:

By default array logging is off.

Default level is the same as the global level set by -level. But App::options, command line, environment, level flag file, and package variables in main are also searched first (for ARRAY_LOG_LEVEL, ARRAY_TRACE, ARRAY_DEBUG, ARRAY_VERBOSE, ARRAY_QUIET, and the similars).

You can also specify category level from environment ARRAY_LOG_CATEGORY_LEVEL.

-dump => BOOL

If set to true then Log::Any::App will dump the generated Log4perl config. Useful for debugging the logging.

PATTERN STYLES ^

Log::Any::App provides some styles for Log4perl patterns. You can specify pattern_style instead of directly specifying pattern. example:

 use Log::Any::App -screen => {pattern_style=>"script_long"};

 Name           Description                        Example output
 ----           -----------                        --------------
 plain          The message, the whole message,    Message
                and nothing but the message.
                Used by dir logging.

                Equivalent to pattern: '%m'

 plain_nl       Message plus newline. The default  Message
                for screen without
                LOG_ELAPSED_TIME_IN_SCREEN.

                Equivalent to pattern: '%m%n'

 script_short   For scripts that run for a short   [234] Message
                time (a few seconds). Shows just
                the number of milliseconds. This
                is the default for screen under
                LOG_ELAPSED_TIME_IN_SCREEN.

                Equivalent to pattern:
                '[%r] %m%n'

 script_long    Scripts that will run for a        [2010-04-22 18:01:02] Message
                while (more than a few seconds).
                Shows date/time.

                Equivalent to pattern:
                '[%d] %m%n'

 daemon         For typical daemons. Shows PID     [pid 1234] [2010-04-22 18:01:02] Message
                and date/time. This is the
                default for file logging.

                Equivalent to pattern:
                '[pid %P] [%d] %m%n'

 syslog         Style suitable for syslog          [pid 1234] Message
                logging.

                Equivalent to pattern:
                '[pid %p] %m'

For each of the above there are also cat_XXX (e.g. cat_script_long) which are the same as XXX but with [cat %c] in front of the pattern. It is used mainly to show categories and then filter by categories. You can turn picking default pattern style with category using environment variable LOG_SHOW_CATEGORY.

And for each of the above there are also loc_XXX (e.g. loc_syslog) which are the same as XXX but with [loc %l] in front of the pattern. It is used to show calling location (file, function/method, and line number). You can turn picking default pattern style with location prefix using environment variable LOG_SHOW_LOCATION.

If you have a favorite pattern style, please do share them.

ENVIRONMENT ^

Below is summary of environment variables used.

Turning on/off logging

 LOG (bool)

Setting general level

 TRACE (bool)       setting general level to trace
 DEBUG (bool)       setting general level to debug
 VERBOSE (bool)     setting general level to info
 QUIET (bool)       setting general level to error (turn off warnings)
 LOG_LEVEL (str)

Setting per-output level

 FILE_TRACE, FILE_DEBUG, FILE_VERBOSE, FILE_QUIET, FILE_LOG_LEVEL
 SCREEN_TRACE and so on
 DIR_TRACE and so on
 SYSLOG_TRACE and so on
 UNIXSOCK_TRACE and so on
 ARRAY_TRACE and so on

Setting per-category level

 LOG_CATEGORY_LEVEL (hash, json)
 LOG_CATEGORY_ALIAS (hash, json)

Setting per-output, per-category level

 FILE_LOG_CATEGORY_LEVEL
 SCREEN_LOG_CATEGORY_LEVEL
 and so on

Controlling extra fields to log

 LOG_SHOW_LOCATION
 LOG_SHOW_CATEGORY

Force-enable or disable color

 COLOR (bool)

Turn on Log::Any::App's debugging

 LOGANYAPP_DEBUG (bool)

Turn on showing elapsed time in screen

 LOG_ELAPSED_TIME_IN_SCREEN (bool)

Note that elapsed time is currently produced using Log::Log4perl's %r (number of milliseconds since the program started, where program started means when Log::Log4perl starts counting time).

Filtering

 LOG_FILTER_TEXT (str)
 LOG_FILTER_NO_TEXT (str)
 LOG_FILTER_CITEXT (str)
 LOG_FILTER_NO_CITEXT (str)
 LOG_FILTER_RE (str)
 LOG_FILTER_NO_RE (str)

Per-output filtering

 {FILE,DIR,SCREEN,SYSLOG,UNIXSOCK,ARRAY}_LOG_FILTER_TEXT (str)
 and so on

Extra things to log

FAQ ^

Why?

I initially wrote Log::Any::App because I'm sick of having to parse command-line options to set log level like --verbose, --log-level=debug for every script. Also, before using Log::Any I previously used Log4perl directly and modules which produce logs using Log4perl cannot be directly use'd in one-liners without Log4perl complaining about uninitialized configuration or some such. Thus, I like Log::Any's default null adapter and want to settle using Log::Any for any kind of logging. Log::Any::App makes it easy to output Log::Any logs in your scripts and even one-liners.

What's the benefit of using Log::Any::App?

You get all the benefits of Log::Any, as what Log::Any::App does is just wrap Log::Any and Log4perl with some nice defaults. It provides you with an easy way to consume Log::Any logs and customize level/some other options via various ways.

And what's the benefit of using Log::Any?

This is better described in the Log::Any documentation itself, but in short: Log::Any frees your module users to use whatever logging framework they want. It increases the reusability of your modules.

Do I need Log::Any::App if I am writing modules?

No, if you write modules just use Log::Any.

Why use Log4perl?

Log::Any::App uses the Log4perl adapter to display the logs because it is mature, flexible, featureful. The other alternative adapter is Log::Dispatch, but you can use Log::Dispatch::* output modules in Log4perl and (currently) not vice versa.

Other adapters might be considered in the future, for now I'm fairly satisfied with Log4perl. It does have a slightly heavy startup cost for my taste, but it is still bearable.

Are you coupling adapter with Log::Any (thus defeating Log::Any's purpose)?

No, producing logs are still done with Log::Any as usual and not tied to Log4perl in any way. Your modules, as explained above, only 'use Log::Any' and do not depend on Log::Any::App at all.

Should portions of your application code get refactored into modules later, you don't need to change the logging part. And if your application becomes more complex and Log::Any::App doesn't suffice your custom logging needs anymore, you can just replace 'use Log::Any::App' line with something more adequate.

How do I create extra logger objects?

The usual way as with Log::Any:

 my $other_log = Log::Any->get_logger(category => $category);

My needs are not met by the simple configuration system of Log::Any::App!

You can use the Log4perl adapter directly and write your own Log4perl configuration (or even other adapters). Log::Any::App is meant for quick and simple logging output needs anyway (but do tell me if your logging output needs are reasonably simple and should be supported by Log::Any::App).

What is array output for?

Logging to a Perl array might be useful for testing/debugging, or (one use-case I can think of) for letting users of your program connect/request your program to view the logs being produced. For example, here is a program that uses a separate thread to listen to Unix socket. Requires perl built with threads enabled.

 use threads;
 use threads::shared;
 BEGIN { our @buf :shared }
 use SHARYANTO::IO::Socket::UNIX::Util qw(create_unix_stream_socket);
 use Log::Any::App '$log', -array => [{array => 'main::buf', max_elems=>100}];

 my $sock = create_unix_stream_socket('/tmp/app-logview.sock');

 # thread to listen to unix socket and receive log viewing instruction
 my $thr = threads->create(
    sub {
        local $| = 1;
        while (my $cli = $sock->accept) {
            while (1) {
                print $cli "> ";
                my $line = <$cli>;
                last unless $line;
                if ($line =~ /\Ar(ead)?\b/i) {
                    print $cli @buf;
                } else {
                    print $cli "Unknown command\n";
                }
            }
        }
    });

 # main thread, application which produces logs
 $|++;
 while (1) {
     $log->warnf("Log (%d) ...", ++$i);
     sleep 1;
 }

After you run this program, you can connect to it, e.g. from another terminal:

 % socat UNIX-CONNECT:/tmp/app-logview.sock -
 > read
 [2014/07/06 23:34:49] Log (1) ...
 [2014/07/06 23:34:50] Log (2) ...
 [2014/07/06 23:34:50] Log (3) ...
 [2014/07/06 23:34:51] Log (4) ...
 [2014/07/06 23:34:51] Log (5) ...

BUGS/TODOS ^

Need to provide appropriate defaults for Windows/other OS.

ROAD TO 1.0 ^

Here are some planned changes/development before 1.0 is reached. There might be some incompatibilities, please read this section carefully.

SEE ALSO ^

Log::Any and Log::Log4perl

Some alternative logging modules: Log::Dispatchouli (based on Log::Dispatch), Log::Fast, Log::Log4perl::Tiny. Really, there are 7,451 of them (roughly one third of CPAN) at the time of this writing.

HOMEPAGE ^

Please visit the project's homepage at https://metacpan.org/release/Log-Any-App.

SOURCE ^

Source repository is at https://github.com/sharyanto/perl-Log-Any-App.

BUGS ^

Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=Log-Any-App

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

AUTHOR ^

Steven Haryanto <stevenharyanto@gmail.com>

COPYRIGHT AND LICENSE ^

This software is copyright (c) 2014 by Steven Haryanto.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

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