[jira] [Commented] (AMBARI-13238) MySQL service check needs to be more robust

["Juanjo Marron (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AMBARI-13238?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15330155#comment-15330155 ] 

Juanjo Marron commented on AMBARI-13238:
----------------------------------------

A new patch is proposed based on the reviews added to the previous one:
https://reviews.apache.org/r/39146/

The patch relies now on the pid (similar to other status check). pid_file is not known a priori for mySQL (it is not a service property similar to other ambari components) and it depends on the OS. 
The pid file location is obatined with  "mysqladmin variables" command (which seems recognized by all the Ambari supported OS). 
The Hive MySQL server instance is started without passing in any parameters so It uses the default configuration. Any other MySQL instance that could be running on the machine would need to be started with explicit config.
Hence just running mysqladmin will return the values for the Hive MySQL instance.
The pid file name is parsed by a new method which has been created to obtain it from the mysqladmin variables return.
Status action relies now on check_process_status() which is already an ambari function.
Unit Test have been modified accordingly to avoid the pgrep verification that could create conflicts with others mysql instances working on the same node.


> MySQL service check needs to be more robust
> -------------------------------------------
>
>                 Key: AMBARI-13238
>                 URL: https://issues.apache.org/jira/browse/AMBARI-13238
>             Project: Ambari
>          Issue Type: Bug
>          Components: ambari-server
>    Affects Versions: 2.0.0, 2.1.0, 2.2.0
>            Reporter: Thomas Friedrich
>            Assignee: Juanjo Marron
>            Priority: Minor
>             Fix For: 3.0.0
>
>         Attachments: AMBARI-13238.patch
>
>
> The mysql service check in mysql_service.py simply checks for the existence of a mysqld process. If an unrelated mysqld service is running on the same node and Hive is configured to run with a MySQL db, the Hive start action won't start the MySQL server instance and the metastore connection fails.



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