Bugfix in Elasticsearch monitoring plugin check_es_system, version 1.12.1 released

Written by Claudio Kuenzler - 0 comments

Published on September 30th 2023 - Listed in Elasticsearch ELK Monitoring

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A new version of check_es_system.sh, a monitoring plugin for Elasticsearch, is available. The latest release 1.12.1 is a bugfix release and fixes a bug in the readonly check type (-t readonly).

Missing privileges not detected

In order to check for read only indexes, check_es_system needs to get access to the Elasticsearch index(es) settings. Depending on which user you are using for the check, the required privileges might not be granted to the user's role.

The previous version(s) did not catch an unauthorized access to the index settings and the check resulted in a parsing error, but still exited with OK:

On the command line this can be verified:

ck@monitoring:~$ /usr/lib/nagios/plugins/check_es_system.sh -H elasticsearch.example.com -u "user" -p "secret" -t readonly
jq: error (at <stdin>:1): Cannot index number with string "settings"
jq: error (at <stdin>:1): Cannot index number with string "settings"
ES SYSTEM OK - Elasticsearch Indexes (_all) are writeable

The error response returned by Elasticsearch's REST API is not properly parsed and the plugin attempts to continue with missing data, leading to the parsing error.

Bugfix now shows missing privilege error

Now with version 1.12.1, the error exception is correctly handled and the plugin will notify accordingly with a CRITICAL state:

ck@monitoring:~$ /usr/lib/nagios/plugins/check_es_system.sh -H elasticsearch.example.com -u "user" -p "secret" -t readonly
ES SYSTEM CRITICAL - Access denied (action [indices:monitor/settings/get] is unauthorized for user [user] with roles [esmonitoring], this action is granted by the index privileges [monitor,view_index_metadata,manage,all])

Adding missing privileges

Obviously the plugin tells you what is missing, but it can't fix the privilege error for you. In the example above, the Elasticsearch user "user" is not allowed to read the settings of the "monitor" index. To solve this, you can add an index privilege on the "monitor" index and give the privilege "monitor" to the user's role:

The documentation of check_es_system was also adjusted accordingly.

With the required index privilege added in Elasticsearch, the check is now working correctly:

ck@monitoring:~$ /usr/lib/nagios/plugins/check_es_system.sh -H elasticsearch.example.com -u "user" -p "secret" -t readonly
ES SYSTEM OK - Elasticsearch Indexes (_all) are writeable

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