document a minimal example for creating LRP with docker image

[shalako]

I want to deploy a docker image to Diego that listens on an arbitrary port (not 8080). I am trying to deploy Redis. Since CF only supports container port 8080, I can't use the diego-cli cf plugin to push docker images.

The documentation on docker support describes architecture and concepts but makes a lot of assumptions that CC is the client, and is of little practical help in crafting the DesiredLRPCreateRequest.

Looking at /v1/desired_lrps after using diego-cli-plugin to push a docker image, there is a lot of configuration but no way to know what is absolutely necessary.

Please document instructions for deploying a basic docker image using only the Receptor API. How about Redis, for example :)

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this. You can view the current status of your issue at: https://www.pivotaltracker.com/story/show/99194390.

[hsiliev]

Hi Shannon,

You can check the https://registry.hub.docker.com/u/cloudfoundry/diego-docker-app-custom image for an example on how you can define a custom port. We do this using:

        "ExposedPorts": {
            "7070/tcp": {}
        },

This image is exercised by DRATS test using cf docker-push.

Of course we still need to document the receptor and probably add a few lines on ports in the docker support doc.

[emalm]

Hi, @shalako,

Yes, I think that's a great suggestion to add more documentation about running Docker-image-based LRPs directly via the Receptor API. In the meantime, here's the minimal JSON payload we worked out to run one instance of the 'redis' Docker image with its preferred port exposed:

{
  "process_guid": "my-redis-server-123",
  "domain": "my-fresh-domain",
  "rootfs": "docker:///redis",
  "instances": 1,
  "action": {
    "run": {
      "path": "/entrypoint.sh",
      "args": [
        "redis-server"
      ],
      "dir": "/data",
      "user": "root"
    }
  },
  "ports": [
    6379
  ]
}

Thanks,
Eric

[shalako]

With Eric's help, I've put together a tutorial for TCP routing with Diego in this PR to the cf-routing-release README: https://github.com/cloudfoundry-incubator/cf-routing-release/pull/11/files

Feel free to poach that content for a similar tutorial on the Diego docs. It would effectively be:

1. Create LRP using Redis Docker image
2. Discover host IP and port for Redis running on Diego
3. Use redis-cli to connect to Redis

[emalm]

Thanks, @shalako, I've added some LRP examples to the receptor documentation, including this Redis one, with some information about how to determine the action and port data from the originating Dockerfile.

Best,
Eric