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 is "main::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 to "prog".
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
Log::ger
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.