We would also be interested in some sort of standardised DockerExecutor which would allow us to add pre and post launch steps.
Also having the ability to run two containers together as one task would be very useful (ie on the same host and linked together) ________________________________ From: Tom Fordon [[email protected]] Sent: 12 August 2015 00:28 To: [email protected] Subject: Re: Custom python executor with Docker We ended up implementing a solution where we did the pre/post steps as separate mesos tasks and adding logic to our scheduler to ensure they were run on the same machine. If anybody knows of a standard / openly available DockerExecutor like what is described below, my team would be greatly interested. On Fri, Aug 7, 2015 at 4:01 AM, Kapil Malik <[email protected]<mailto:[email protected]>> wrote: Hi, We have a similar usecase while running multi-user workloads on mesos. Users provide docker images encapsulating application logic, which we (we = say some “Central API”) schedule on Chronos / Marathon. However, we need to run some standard pre / post steps for every docker submitted by users. We have following options – 1. Ask every user to embed their logic inside a pre-defined docker template which will perform pre/post steps. ==> This is error prone, makes us dependent on whether the users followed template, and not very popular with users either. 2. Extend every user docker (FROM <>) and find a way to add pre-post steps in our docker. Refer this docker when scheduling on chronos / marathon. ==> Building new dockers does not scale as users and applications grow 3. Write a custom executor which will perform the pre-post steps and manage the user docker lifetime. ==> Deals with user docker lifetime and is obviously complex. Is there a standard / openly available DockerExecutor which manages the docker lifetime and which I can extend to build my custom executor? This way I will be concerned only with my custom logic (pre/post steps) and still get benefits of a standard way to manage docker containers. Btw, thanks for the meaningful discussion below, it is very helpful. Thanks and regards, Kapil Malik | [email protected]<mailto:[email protected]> | 33430 / 8800836581 From: James DeFelice [mailto:[email protected]<mailto:[email protected]>] Sent: 09 April 2015 18:12 To: [email protected]<mailto:[email protected]> Subject: Re: Custom python executor with Docker If you can run the pre/post steps in a container then I'd recommend building a Docker image that includes your pre/post step scripting + your algorithm and launching it using the built-in mesos Docker containerizer. It's much simpler than managing the lifetime of the Docker container yourself. On Thu, Apr 9, 2015 at 8:29 AM, Tom Fordon <[email protected]<mailto:[email protected]>> wrote: Thanks for all the responses, I really appreciate the help. Let me try to state my problem more clearly Our project is performing file-based data processing. I would like to keep the actual algorithm as contained as possible since we are in an R&D setting and will be getting untested code. We have some pre/post steps that need to be run on the same box as the actual algorithm: downloading/uploading files and database calls. We can run the pre/post steps and algorithm within the same container. The algorithm will be a little less contained, but it will work. Docker letting you specify a cgroup parent is really exciting. If I invoke a docker container with the executor as the cgroup-parent are there any other steps I need to perform? Would I need to do anything special to make mesos aware of the resource usage, or is that handled since the docker process would be in the executors cgroup? Thanks again, Tom On Tue, Apr 7, 2015 at 8:10 PM, Timothy Chen <[email protected]<mailto:[email protected]>> wrote: Hi Tom(s), Tom Arnfeld is right, if you want to launch your own docker container in your custom executor you will have to handle all the issues yourself and not able to use the Docker containerizer at all. Alternatively, you can actually launch your custom executor in a Docker container by Mesos, by specifying the ContainerInfo in the ExecutorInfo. What this means is that your custom executor is already running in a docker container, and you can do your custom logic afterwards. This does means you can simply just launch multiple containers in the executor anymore. If there is something you want to do and doesnt' fit these let us know what you're trying to achieve and we can see what we can do. Tim On Tue, Apr 7, 2015 at 4:15 PM, Tom Arnfeld <[email protected]<mailto:[email protected]>> wrote: > It's not possible to invoke the docker containerizer from outside of Mesos, > as far as I know. > > If you persue this route, you can run into issues with orphaned containers > as your executor may die for some unknown reason, and the container is still > running. Recovering from this can be tricky business, so it's better if you > can adapt your framework design to fit within the Mesos Task/Executor > pattern. > > -- > > Tom Arnfeld > Developer // DueDil > > (+44) 7525940046<tel:%28%2B44%29%207525940046> > 25 Christopher Street, London, EC2A 2BS > > > On Mon, Apr 6, 2015 at 7:00 PM, Vinod Kone > <[email protected]<mailto:[email protected]>> wrote: >> >> Tim, do you want answer this? >> >> On Wed, Apr 1, 2015 at 7:27 AM, Tom Fordon >> <[email protected]<mailto:[email protected]>> wrote: >>> >>> Hi. I'm trying to understand using docker within a custom executor. For >>> each of my tasks, I would like to perform some steps on the node before >>> launching a docker container. I was planning on writing a custom python >>> executor for this, but I wasn't sure how to launch docker from within this >>> executor. >>> >>> Can I just call docker in a subprocess using the ContainerInfo from the >>> Task? If I do this, how does the Containerizer fit in? >>> >>> Thank you, >>> Tom Fordon >> >> > -- James DeFelice 585.241.9488<tel:585.241.9488> (voice) 650.649.6071<tel:650.649.6071> (fax)
