[jira] [Commented] (MESOS-2368) Send Docker container information back to the scheduler

["Timothy Chen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MESOS-2368?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14507963#comment-14507963 ] 

Timothy Chen commented on MESOS-2368:
-------------------------------------

Renamed this issue as we are going to scope this ticket to just sending back docker inspect information back.

So here is the planned implementation proposal:
Once the new docker executor is merged, we can modify the docker executor that after running the container to send `docker inspect <container>` output in the first TASK_RUNNING StatusUpdate data field, and will only send this once.
In the future if we introduce health checks for docker containers which we will send mulitple TASK_RUNNING updates, we will still only send it on the first status update.


> Send Docker container information back to the scheduler
> -------------------------------------------------------
>
>                 Key: MESOS-2368
>                 URL: https://issues.apache.org/jira/browse/MESOS-2368
>             Project: Mesos
>          Issue Type: Improvement
>          Components: containerization, docker
>            Reporter: Henning Schmiedehausen
>            Assignee: Timothy Chen
>
> So that description is not very verbose. Here is my use case:
> In our usage of Mesos and Docker, we assign IPs when the container starts up. We can not allocate the IP ahead of time, but we must rely on docker to give our containers their IP. This IP can be examined through "docker inspect". 
> We added code to the docker containerizer that will pick up this information and add it to an optional protobuf struct in the TaskStatus message. Therefore, when the executor and slave report a task as running, the corresponding message will contain information about the IP address that the container was assigned by docker and we can pick up this information in our orchestration framework. E.g. to drive our load balancers.
> There was no good way to do that in stock Mesos, so we built that back channel. However, having a generic channel (not one for four pieces of arbitrary information) from the executor to a framework may be a good thing in general. Clearly, this information could be transferred out of band but having it in the standard Mesos communication protocol turned out to be very elegant.
> To turn our current, hacked, prototype into something useful, this is what I am thinking:
> - TaskStatus gains a new, optional field:
>   - optional TaskContext task_context = 11; (better name suggestions very welcome)
> - TaskContext has optional fields:
>   - optional ContainerizerContext containerizer_context = 1;
>   - optional ExecutorContext executor_context = 2;
> Each executor and containerizer can add information to the TaskContext, which in turn is exposed in TaskStatus. To avoid crowding of the various fields, I want to experiment with the nested extensions as described here: http://www.indelible.org/ink/protobuf-polymorphism/
> At the end of the day, the goal is that any piece that is involved in executing code on the slave side can send information back to the framework along with TaskStatus messages. Any of these fields should be optional to be backwards compatible and they should (same as any other messages back) be considered best effort, but it will allow an effective way to communicate execution environment state back to the framework and allow the framework to react on it.
> I am planning to work on this an present a cleaned up version of our prototype in a bit.



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