Log::Any::App - An easy way to use Log::Any in applications
version 0.29
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'...'
You then customize level 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
But if you need to customize level (and other stuffs) from the script, you can:
use Log::Any::App '$log', -syslog => 1, # turn on syslog logging, default is autodetect -screen => 0, # turn off screen logging, default is on -file => {path=>'/foo/bar', rotate=>'10M', histories=>10}; # customize file logging, default file logging is on unless -e
For more customization like categories, per-category level, per-output level, multiple outputs, string patterns, etc see "USING AND EXAMPLES". For details on how Log::Any::App chooses defaults, read documentation on init().
Log::Any::App is a convenient combo for Log::Any and Log::Log4perl (although alternative backends beside Log4perl might be considered in the future). To use Log::Any::App you need to be sold on the idea of Log::Any first, so please do a read up on that first.
The goal of Log::Any::App is to provide developers an easy and concise way to add logging to their *applications*. That is, instead of modules; modules remain using Log::Any to produce logs. Applications can upgrade to full Log4perl later when necessary, although in my experience, they usually don't.
With Log::Any::App, you can replace this code in your application:
use Log::Any '$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.
To use Log::Any::App, just do:
use Log::Any::App '$log';
or from the command line:
% perl -MLog::Any::App -MModuleThatUsesLogAny -e ...
This will send logs to screen as well as file (unless -e scripts, which only logs to screen). Default log file is ~/$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 can be done from the script or outside the script. From the script:
use Log::Any::App '$log', -level => 'debug';
but oftentimes what you want is changing level without modifying the script itself.
and then you can use environment variable:
TRACE=1 script.pl; # setting level to trace DEBUG=1 script.pl; # setting level to debug VERBOSE=1 script.pl; # setting level to info QUIET=1 script.pl; # setting level to error LOG_LEVEL=trace script.pl; # setting a specific log level
or command-line options:
script.pl --trace script.pl --debug script.pl --verbose script.pl --quiet script.pl --log_level=debug; # '--log-level debug' will also do
Log::Any::App won't consume the command-line options from @ARGV and thus won't interfere with command-line processing modules like Getopt::Long or App::Options. You might want to define these options in your option processing module though, or it might complain about unknown options. Or alternatively you can use environment variables instead.
The default log level is 'warn'. You can change this using:
use Log::Any::App '$log'; BEGIN { our $Log_Level = 'info' }
and then you can still use environment or command-line options to override the setting.
Logging level can also be specified on a per-output level. For example, if you want your script to be chatty on the screen but still logs to file at the default 'warn' level:
SCREEN_VERBOSE=1 script.pl SCREEN_DEBUG=1 script.pl SCREEN_TRACE=1 script.pl SCREEN_LOG_LEVEL=info script.pl script.pl --screen_verbose script.pl --screen-debug script.pl --screen-trace=1 script.pl --screen-log-level=info # and so on
Similarly, to set only file level, use FILE_VERBOSE, FILE_LOG_LEVEL, --file-trace, etc.
As with setting default level, you can also set default level on a per-output basis:
use Log::Any::App '$log'; BEGIN { our $Screen_Log_Level = 'off'; our $File_Quiet = 1; # setting file level to 'error' # and so on }
If a per-output level is not specifed, it will default to the general log level.
To disable a certain output, you can do this:
use Log::Any::App '$log', -file => 0;
or:
use Log::Any::App '$log', -screen => {level=>'off'};
and this won't allow it to be reenabled from outside the script. However if you do this:
use Log::Any::App; BEGIN { our $Screen_Log_Level = 'off' }
then by default screen logging is turned off but you will be able to override the screen log level using environment or command-line options (SCREEN_DEBUG, --screen-verbose, and so on).
By default Log::Any::App will use ~/$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 '$log', -file => '/path/to/file';
Each output argument can accept a hashref to specify various options. For example:
use Log::Any::App '$log', -screen => {color=>0}, # never use color -file => {path=>'/var/log/foo', rotate=>'10M', histories=>10, },
For all the available options of each output, see the init() function.
Logging to syslog is enabled by default if your script looks like 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
but if you are certain you don't want syslog logging:
use Log::Any::App -syslog => 0;
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 '$log', -dir => 1;
For all the available options of directory output, see the init() function.
Each output argument can accept an arrayref to specify more than one output. For example below is a code to log to three files:
use Log::Any::App '$log', -file => [1, # the default file logging to ~/$NAME.log "/var/log/log1", {path=>"/var/log/debug_foo", category=>'Foo', level=>'debug'}];
Suppose you want to shut up Foo, Bar::Baz, and Qux's logging because they are too noisy:
use Log::Any::App '$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, -file => "/var/log/foo", -screen => { category_level => {} }; # do not do per-category level
Sometimes, for security/audit reasons, you don't want to allow script caller to change logging level. To do so, just specify the 'level' option in the script during 'use' statement.
To see the Log4perl configuration that is generated by Log::Any::App and how it came to be, set environment LOGANYAPP_DEBUG to true.
None is exported.
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:
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?)
Change the program name. Default is taken from $0.
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', ...], );
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.
Specify log level for all outputs. Each output can override this value. The default log level is determined as follow:
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).
trace
debug
info
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).
Otherwise, it will look for environment variables: LOG_LEVEL, QUIET. VERBOSE, DEBUG, TRACE.
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.
main
$Log_Level
$LOG_LEVEL
$log_level
$Quiet
$QUIET
$quiet
$Verbose
$VERBOSE
$verbose
$Trace
$TRACE
$trace
$Debug
$DEBUG
$debug
If everything fails, it defaults to 'warn'.
Specify output to one or more files, using Log::Dispatch::FileRotate.
If the argument is a false boolean value, file logging will be turned off. If argument is a true value that matches /^(1|yes|true)$/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), date_pattern (will be passed to DatePattern argument in FileRotate's constructor), tz (will be passed to TZ argument in FileRotate'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).
level
path
max_size
histories
date_pattern
tz
category
category_level
pattern_style
pattern
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.
/var/log/$NAME.log
-name
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 $NAME.log.
Default rotating behaviour is no rotate (max_size = 0).
Default level for file is the same as the global level set by -level. But App::options, command line, environment, and package variables in main are also searched first (for FILE_LOG_LEVEL, FILE_TRACE, FILE_DEBUG, FILE_VERBOSE, FILE_QUIET, and the similars).
Log messages using Log::Dispatch::Dir. Each message is logged into separate files in the directory. Useful for dumping content (e.g. HTML, network dumps, or temporary results).
If the argument is a false boolean value, dir logging will be turned off. If argument is a true value that matches /^(1|yes|true)$/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).
max_age
filename_pattern
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.
/var/log/$NAME/
Default rotating parameters are: histories=1000, max_size=0, max_age=undef.
Default level for dir logging is the same as the global level set by -level. But App::options, command line, environment, and package variables in main are also searched first (for DIR_LOG_LEVEL, DIR_TRACE, DIR_DEBUG, DIR_VERBOSE, DIR_QUIET, and the similars).
Log messages using Log::Log4perl::Appender::ScreenColoredLevels.
If the argument is a false boolean value, screen logging will be turned off. If argument is a true value that matches /^(1|yes|true)$/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).
color
stderr
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, 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).
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).
ident
facility
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) then syslog logging is turned on by default and facility is set to daemon, otherwise the default is off.
daemon
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, and package variables in main are also searched first (for SYSLOG_LOG_LEVEL, SYSLOG_TRACE, SYSLOG_DEBUG, SYSLOG_VERBOSE, SYSLOG_QUIET, and the similars).
If set to true then Log::Any::App will dump the generated Log4perl config. Useful for debugging the logging.
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' 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. 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'
If you have a favorite pattern style, please do share them.
You get all the benefits of Log::Any, as what Log::Any::App does is just wrap Log::Any and Log::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.
You still produce logs with Log::Any so later should portions of your application code get refactored into modules, 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.
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.
No, if you write modules just use Log::Any.
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.
Note that producing logs are still done with Log::Any as usual and not tied to Log4perl in any way.
The usual way as with Log::Any:
my $other_log = Log::Any->get_logger(category => $category);
You can use 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).
Need to provide appropriate defaults for Windows/other OS.
Probably: SCREEN0_DEBUG, --file1-log-level, etc.
Log::Any and Log::Log4perl
Some alternative logging modules: Log::Dispatchouli (based on Log::Dispatch), Log::Fast, Log::Log4perl::Tiny. Really, there are around 7,451 of them (roughly one third of CPAN, at the time of this writing).
Steven Haryanto <stevenharyanto@gmail.com>
This software is copyright (c) 2011 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.
To install Log::Any::App, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Log::Any::App
CPAN shell
perl -MCPAN -e shell install Log::Any::App
For more information on module installation, please visit the detailed CPAN module installation guide.