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https://issues.apache.org/jira/browse/AMBARI-7985?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14185709#comment-14185709
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Siddharth Wagle commented on AMBARI-7985:
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_ With this, aren't stages ordered and guaranteed not to start unless the
previous stage completes successfully?_
Yes that will be guaranteed by the Action Execution framework.
- There is a ServiceActionManager which is invoked from ActionScehduler, I
don't think we should create separate ActionScheduler for server actions.
- Another thing that is unclear to me is, if the server action is a Host Role
Command (HRC), then this is basically something queued up to be executed by the
agent running on Ambari server? Or is it a java class that is a part of a jar
file and in the class path of AmabriServer?
- If it is a conventional HRC, it should be a part of the Action queue for the
server host. (There is 1 queue of actions per host).
*Note*: In certain Ambari deployments the Amabri server might not have an agent
running on the same host as the server.
- The ActionScehduler, is non-blocking it reads stages from DB and queues up
actions, the delay is that heartbeats are resposible for dequeue and heartbeat
happen every 6 seconds.
> Allow for server-side commands
> ------------------------------
>
> Key: AMBARI-7985
> URL: https://issues.apache.org/jira/browse/AMBARI-7985
> Project: Ambari
> Issue Type: New Feature
> Components: ambari-server
> Affects Versions: 2.0.0
> Reporter: Robert Levas
> Assignee: Robert Levas
> Labels: ambari-server, commands, server, server-side, tasks
> Fix For: 2.0.0
>
>
> Ambari currently handles _client-/agent-side_ commands; however there is no
> ability to handle _server-side_ commands. Server-side commands should be
> specified as a task in a stage and managed along with the stage.
> *Use Case:* Generate principals and keytabs on the Ambari server before
> sending the keytabs to their relevant hosts.
> *Implementation:* To add the concept of a server-side task:
> * update {{org.apache.ambari.server.serveraction.ServerAction}} to be an
> _abstract class_
> ** _server-side_ tasks must implement this class
> * reuse existing _host_role_command_ and _execution_command_ data
> ** _server-side_ tasks are to have a role of {{AMBARI_SERVER_ACTION}}
> ** _server-side_ execution command data should be encapsulated as JSON and
> specify the ServerAction implementation class and any needed payload data
> * {{org.apache.ambari.server.actionmanager.ActionScheduler}} and
> {{org.apache.ambari.server.serveraction.ServerActionManagerImpl}} need to be
> updated to handle the execution of server-side tasks
> ** each _server-side_ task should be executed in its own thread.
> *** _server_side_ tasks should be executed in (staged) order, serially - not
> in parallel
> *** _server_side_ tasks should ensure not to mess up _stage_ ordering
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