Any information system saves operations and actions in special text files – logs. In order for the IS to save logs properly, and administrators to be able to access them, they use specialized software. In the article we will talk about one utility – Logrotate, which is installed on the Ubuntu 16.04 server OS.
Preliminary preparation
Logrotate archives log files automatically according to the specified parameters. If you do not compress the logs and do not delete old versions, then over time you will run out of space on your hard drive. To avoid this situation, system administrators use programs.
Before setting up logging, we connect to the server platform via SSH and perform the following actions on behalf of the superuser.
Installation
Having connected to Ubuntu Server, we check the availability of the program with the command:
logrotate -- version
Important! As of mid-August 2019, release 3.15.0.
If instead of a response in the form of numbers, the user receives a message that the utility is not installed, then we will install Ubuntu using standard means.
Setup
The standard configuration of Logrotate is stored in two ways:
1. The /etc/logrotate.conf file stores some of the default configurations. It also contains archiving templates for non-system files.
2. The second path – /etc/logrotate.d/ is designed to save third-party parameters that the administrator sets on his own. Rotation templates for system utilities (apt, rsyslog, dpkg, etc.) are stored here.
After installation, the utility uses a standard pattern of weekly data rotation. According to the parameters, logs are archived that belong to the root user and the syslog system group.
Let’s go to the second file, which is responsible for the apt system command, in order to study the standard options.
cat /etc/logrotate.d/apt
There are two sections inside:
Screenshot #1. File contents.
As you can see, the data is stored in the form of identical blocks of conditions:
- rotate 12 tells the utility to keep the last twelve logs;
- the second line means the content is updated once a month;
- compress is an archiving command, by default the standard utility of Linux systems is used – gzip, if you want to change it to another one, then specify the keys after the command;
- the fourth parameter tells logrotate not to save an error message if there is no log file;
- the last parameter cancels archiving if the log is empty.
If you need your own script for rotation, then create it in the /etc/logrotate.d/ directory. Below is a test version of creating a rotation template.
Example #1
Initial: A virtual server exists. It is necessary to save logs in access.log and error.log. They are located in the /var/log/example-app/ directory. The server has a www-data user and a group with the same name.
Create a file with a text editor.
sudo vi /etc/logrotate.d/example-app
Paste the following commands into it:
Screenshot #2. File example.
Important! If you need detailed information about the command, then use the man utility. For example,
man logrotate
After adding the information, save the changes. Testing the result:
sudo logrotate /etc/logrotate.conf –debug
Important! The working window of the terminal displays information about the operations currently performed by logrotate.
Example #2
Background: Logrotate is running under the account name Sammy. Log files are saved to the /home/sammy/logs/ directory. You need to set up archiving at an hourly interval.
Important! The settings will be done in a different directory than /etc/logrotate.d.
Create a new configuration using the vi editor.
vi /home/sammy/logrotate.conf
Let’s add the following information to it:
/home/sammy/logs/*.log {
hourly
missingok
rotate 24
compress
create
}
The hourly and rotate 24 commands indicate that archiving occurs hourly. Close the file with saving.
For verification, we will create a test file in which the logs will be stored.
cd ~
mkdir logs
touch logs/access.log
Now let’s tell logrotate a new path to save the information.
logrotate /home/sammy/logrotate.conf --state /home/sammy/logrotate-state –verbose
After launching the utility, the following will appear on the monitor:
Screenshot #3. Test result.
For the logging program, this is a new file.
To run the utility hourly, let’s configure the cron job scheduler. Let’s open it:
crontab –e
Let’s put the last line in the form:
15 * * * * /usr/sbin/logrotate /home/sammy/logrotate.conf --state /home/sammy/logrotate-state
Save changes, close the file.
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