NAME
Log::ger::App - An easy way to use Log::ger in applications
VERSION
version 0.025
SYNOPSIS
In your script:
use Log::ger::App;
use Your::App::Module; # your module which uses Log::ger to do its logging
If you also do logging in your script:
use Log::ger::App;
use Log::ger;
log_warn("Some log ...");
DESCRIPTION
This module basically loads Log::ger::Output::Composite with some sensible defaults and allows customizing some aspects via environment variable.
Default outputs
Code Screen File Syslog
------------------------------ ------ ---- ------
One-liner (-e) y - -
Script running as normal user y ~/PROGNAME.log -
Script running as root y /var/log/PROGNAME.log -
Daemon - /var/log/PROGNAME.log y
Determining if script is a daemon
Log::ger::App assumes your script is a daemon if some daemon-related modules are loaded, e.g. App::Daemon, HTTP::Daemon, Net::Daemon, etc (see the source code for the complete list). Alternatively, you can also set $main::IS_DAEMON
to 1 (0) to specifically state that your script is (not) a daemon. Or, you can set it via import argument (see "import").
Setting general log level
Via import argument 'level'. You can set general log level via import argument level
(see "import") but users of your script will not be able to customize it:
use Log::ger::App level => 'debug'; # hard-coded to debug, not recommended
Via environment variables. You can also set general log level from environment using LOG_LEVEL
(e.g. LOG_LEVEL=trace
to set level to trace or LOG_LEVEL=0
to turn off logging). Alternatively, you can set to trace
using TRACE=1
, or debug
with DEBUG=1
, info
with VERBOSE=1
, error
with QUIET=1
.
Via import argument 'default_level'. If the environment variables does not provide a value, next the import argument default_level
is consulted. This is the preferred method of setting default level:
use Log::ger::App default_level => 'info'; # be verbose by default. unless changed by env vars
Via main package variable $main::Default_Log_Level. The next value to be consulted is the main package variable $main::Default_Log_Level
. The name of the variable can be customized using the import argument default_level_var_name
. Note that you need to set the variable's value before loading Log::ger::App, so this does not work:
use Log::ger::App;
our $Default_Log_Level = 'info';
this does not also:
our $Default_Log_Level = 'info';
use Log::ger::App;
but this does:
BEGIN { our $Default_Log_Level = 'info' }
use Log::ger::App;
Fallback value "warn". The fallback level is warn, if all the above does not provide a value.
Setting per-output log level
Via environment variables. You can set level for each output using OUTPUT_NAME_{LOG_LEVEL|TRACE|DEBUG|VERBOSE|QUIET
} environment variables. For example, SCREEN_DEBUG=1
to set screen level to debug
or FILE_LOG_LEVEL=off
to turn off file logging.
General level. If the environment variables do not provide a value, the general level (see "Setting general log level") will be used.
Showing timestamp
Timestamps are shown in log files. On the screen, timestamps are not shown by default. To show timestamps on the screen, set LOG_ADD_TIMESTAMP
to true. For example, when timestamps are not shown:
myprog: First log message
myprog: Doing task 1 ...
myprog: Doing task 2 ...
When timestamps are shown:
myprog: [2018-08-30T15:14:50] First log message
myprog: [2018-08-30T15:14:50] Doing task 1 ...
myprog: [2018-08-30T15:15:01] Doing task 2 ...
FUNCTIONS
import
Usage:
$pkg->import(%args)
Arguments:
level
str|num. Explicitly set a hard-coded level. Not recommended because of lack of flexibility. See instead: "default_level".
default_level
str|num. Instead of hard-coding level with "level", you can set a default level. Environment variables will be consulted first (as described in "DESCRIPTION") before falling back to this level.
default_level_var_name
str. Optional. Name of scalar variable (without the sigil) to be consulted for the default level (after the
default_level
import argument). If the name of the variable does not contain package name, it will be assumed to be in the "main" package. The default value ismain::Default_Log_Level
.name
str. Explicitly set program name. Otherwise, default will be taken from
$0
(after path and '.pl' suffix is removed) or set toprog
.Program name will be shown on the screen, e.g.:
myprog: First log message myprog: Doing task 1 ... myprog: Doing task 2 ... myprog: Exiting ...
file_name
str. Explicitly set log filename. By default, filename will be set to name.log.
file_dir
str. Explicitly set log file's directory. By default, it is user's home (if not running as root), or /var/log (if running as root).
daemon
bool. Explicitly tell Log::ger::App that your application is a daemon or not. Otherwise, Log::ger::App will try some heuristics to guess whether your application is a daemon: from the value of
$main::IS_DAEMON
and from the presence of modules like HTTP::Daemon, Proc::Daemon, etc.outputs
hash. Specify extra outputs. Will be added to Log::ger::Output::Composite's
outputs
configuration.Example:
outputs => { DirWriteRotate => { conf => {dir=>'/home/ujang/log', max_size=>10_000}, level => 'off', category_level => {Dump => 'info'}, }, },
extra_conf
Hash. Specify extra configuration, will be added to Log::ger::Output::Composite's configuration.
Example:
extra_conf => { category_level => {Dump => 'off'}, },
VARIABLES
$DEBUG
Default is false. If set to true, will show more details about how log level, etc is set.
@IMPORT_ARGS
Will be set with the last aguments passed to import(), for informational purposes.
ENVIRONMENT
LOG_GER_APP_DEBUG
Used to set the default for $DEBUG
.
LOG_ADD_LOCATION
Boolean. Default to false. If set to true, will add location to the log:
[file /some/path.pm:123]
LOG_ADD_STACK_TRACE
Boolean. Default to false. If set to true, will add stack trace to the log:
[stack ...]
LOG_ADD_TIMESTAMP
Boolean. Default to false. If set to true, will add timestamps to the screen log. Normally, timestamps will only be added to the file log.
LOG_ADD_MEMORY_INFO
Boolean. Default to false. If set to true, will add memory info to log (see %_{vmtime}
pattern in Log::ger::Layout::Pattern).
LOG_LEVEL
String. Can be set to off
or numeric/string log level.
TRACE
Bool.
DEBUG
Bool.
VERBOSE
Bool.
QUIET
Bool.
SCREEN_LOG_LEVEL
SCREEN_TRACE
SCREEN_DEBUG
SCREEN_VERBOSE
SCREEN_QUIET
FILE_LOG_LEVEL
FILE_TRACE
FILE_DEBUG
FILE_VERBOSE
FILE_QUIET
SYSLOG_LOG_LEVEL
SYSLOG_TRACE
SYSLOG_DEBUG
SYSLOG_VERBOSE
SYSLOG_QUIET
FAQS
How do I turn off file logging?
By default, file logging is on unless running as a Perl one-liner (under perl
's -e
).
To explicitly turn file logging off, you can set FILE_LEVEL environment variable to off
, for example:
BEGIN { $ENV{FILE_LEVEL} //= "off" }
use Log::ger::App;
How do I turn off screen logging?
By default, screen logging is on unless script is a daemon.
To explicitly turn screen logging off, you can set SCREEN_LEVEL environment variable to off
, for example:
BEGIN { $ENV{SCREEN_LEVEL} //= "off" }
use Log::ger::App;
How do I turn off syslog logging?
By default, syslog logging is on if script is a daemon.
To explicitly turn syslog logging off, you can set SYSLOG_LEVEL environment variable to off
, for example:
BEGIN { $ENV{SYSLOG_LEVEL} //= "off" }
use Log::ger::App;
Why doesn't setting $main::Default_Log_Level work?
Note that you need to set the variable's value before loading Log::ger::App, so this does not work:
use Log::ger::App;
our $Default_Log_Level = 'info';
this does not also:
our $Default_Log_Level = 'info';
use Log::ger::App;
but this does:
BEGIN { our $Default_Log_Level = 'info' }
use Log::ger::App;
Why doesn't re-setting log level using Log::ger::Util::set_level() work?
(This FAQ item is from Log::ger::Output::Composite's, slightly modified).
The Log::ger::Output::Composite plugin that Log::ger::App uses sets its own levels and logs using a multilevel routine (which gets called for all levels). Re-setting log level dynamically via Log::ger::Util's set_level
will not work as intended, which is fortunate or unfortunate depending on your need.
If you want to override all levels settings with a single value, you can use Log::ger::Output::Composite::set_level
, for example:
Log::ger::Util::set_level('trace'); # also set this too
Log::ger::Output::Composite::set_level('trace');
This sets an internal level setting which is respected and has the highest precedence so all levels settings will use this instead. If previously you have:
Log::ger::Output->set(Composite => (
outputs => {
File => {conf=>{path=>'/foo'}, level=>'debug'},
Screen => {level=>'info', category_level=>{MyApp=>'warn'}},
},
category_level => {
'MyApp::SubModule1' => 'debug',
},
));
then after the Log::ger::Output::Composite::set_level('trace')
, all the above per-category and per-output levels will be set to trace
.
SEE ALSO
AUTHOR
perlancar <perlancar@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2024, 2022, 2021, 2020, 2019, 2018, 2017 by perlancar <perlancar@cpan.org>.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.