Summary

This article describes how to configure log rotation for an embedded Elasticsearch instance that is installed alongside Bitbucket Server. The configuration below configures rotation in such a way that the bitbucket-search.log file will be rotated every time it exceeds 25MB in size. The maximum number of log files retained for a single day is set to 10. Both parameters (size and number of files) can be configured as needed. This approach has been tested with Elasticsearch instances that are bundled with Bitbucket Server, however this should also work with a standalone Elasticsearch instance, such as when using Bitbucket Data Center.

Environment

Elasticsearch version 5 and newer
Bitbucket Server version 7.x

Solution

Here are the steps to implement size-based log rotation for ES

1. Navigate to <Bitbucket_Home>/shared/search. You should see a file named log4j2.properties.

2. Edit the log4j2.properties  file and remove or comment out (by prefixing them with #)the following lines:

   log4j2.properties

   appender.rolling.filePattern = ${sys:es.logs.base_path}${sys:file.separator}${sys:es.logs.cluster_name}-%d{yyyy-MM-dd}.log
   appender.rolling.policies.time.type = TimeBasedTriggeringPolicy
   appender.rolling.policies.time.interval = 1
   appender.rolling.policies.time.modulate = true

3. Then add the following lines:


   log4j2.properties

   appender.rolling.filePattern = ${sys:es.logs.base_path}${sys:file.separator}${sys:es.logs.cluster_name}-%d{yyyy-MM-dd}-%i.log
   appender.rolling.policies.size.type = SizeBasedTriggeringPolicy
   appender.rolling.policies.size.size = 25MB
   appender.rolling.strategy.type = DefaultRolloverStrategy
   appender.rolling.strategy.max = 10

4. Restart Bitbucket Server, which will restart the bundled Elasticsearch instance. If you are attempting to apply this configuration to a standalone Elasticsearch instance, you do not need to restart Bitbucket Server, but will need to restart Elasticsearch manually. Once the restart is complete, Elasticsearch will be rotating files as configured, and once the log file has reached the configured threshold, you should be seeing multiple log files in the log directory, such as the ones below.

   Bitbucket_Home/log/search

   bitbucket_search-2022-02-08-10.log
   bitbucket_search-2022-02-08-1.log
   bitbucket_search-2022-02-08-2.log
   bitbucket_search-2022-02-08-3.log
   bitbucket_search-2022-02-08-4.log
   bitbucket_search-2022-02-08-5.log
   bitbucket_search-2022-02-08-6.log
   bitbucket_search-2022-02-08-7.log
   bitbucket_search-2022-02-08-8.log
   bitbucket_search-2022-02-08-9.log
   bitbucket-search.log