Logs

Tarantool logs important events to a file, e.g. /var/log/tarantool/my_app.log. To build the log file path, tarantoolctl takes the instance name, prepends the instance directory and appends “.log” extension.

Let’s write something to the log file:

$ tarantoolctl enter my_app
/bin/tarantoolctl: connected to unix/:/var/run/tarantool/my_app.control
unix/:/var/run/tarantool/my_app.control> require('log').info("Hello for the manual readers")
---
...

Then check the logs:

$ tail /var/log/tarantool/my_app.log
2017-04-04 15:54:04.977 [29255] main/101/tarantoolctl C> version 1.7.3-382-g68ef3f6a9
2017-04-04 15:54:04.977 [29255] main/101/tarantoolctl C> log level 5
2017-04-04 15:54:04.978 [29255] main/101/tarantoolctl I> mapping 134217728 bytes for tuple arena...
2017-04-04 15:54:04.985 [29255] iproto/101/main I> binary: bound to [::1]:3301
2017-04-04 15:54:04.986 [29255] main/101/tarantoolctl I> recovery start
2017-04-04 15:54:04.986 [29255] main/101/tarantoolctl I> recovering from `/var/lib/tarantool/my_app/00000000000000000000.snap'
2017-04-04 15:54:04.988 [29255] main/101/tarantoolctl I> ready to accept requests
2017-04-04 15:54:04.988 [29255] main/101/tarantoolctl I> set 'checkpoint_interval' configuration option to 3600
2017-04-04 15:54:04.988 [29255] main/101/my_app I> Run console at unix/:/var/run/tarantool/my_app.control
2017-04-04 15:54:04.989 [29255] main/106/console/unix/:/var/ I> started
2017-04-04 15:54:04.989 [29255] main C> entering the event loop
2017-04-04 15:54:47.147 [29255] main/107/console/unix/: I> Hello for the manual readers

When logging to a file, the system administrator must ensure logs are rotated timely and do not take up all the available disk space. With tarantoolctl, log rotation is pre-configured to use logrotate program, which you must have installed.

File /etc/logrotate.d/tarantool is part of the standard Tarantool distribution, and you can modify it to change the default behavior. This is what this file is usually like:

/var/log/tarantool/*.log {
    daily
    size 512k
    missingok
    rotate 10
    compress
    delaycompress
    create 0640 tarantool adm
    postrotate
        /usr/bin/tarantoolctl logrotate `basename ${1%%.*}`
    endscript
}

If you use a different log rotation program, you can invoke tarantoolctl logrotate command to request instances to reopen their log files after they were moved by the program of your choice.

Tarantool can write its logs to a log file, syslog or a program specified in the configuration file (see log parameter).

By default, logs are written to a file as defined in tarantoolctl defaults. tarantoolctl automatically detects if an instance is using syslog or an external program for logging, and does not override the log destination in this case. In such configurations, log rotation is usually handled by the external program used for logging. So, tarantoolctl logrotate command works only if logging-into-file is enabled in the instance file.

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Logs