Docker load image from alloc/ directory

Nomad
1

Is it not possible to load a Docker image from the alloc/ directory?

I have a Docker image archive that I retrieve in a separate task and store in the alloc/ directory. Then I try to load it:

    task "app" {
      driver = "docker"
      config {
        load  = "${NOMAD_ALLOC_DIR}/docker-image.tar"
        image = "docker-image"
      }
    }

Which gives me:

unable to open image archive:
  open /var/lib/nomad/alloc/4544-snip-c4df/app/local/alloc/docker-image.tar:
  no such file or directory
2

No matter what I specify, Nomad (or Docker) always tries to load from /taskname/local/.

Does the load config option not have access to the alloc directory?

If I use the volumes config option, could I bind a path that the Docker container can use? I have tried this already, and it does not seem to work.

Is there any other way to get a local file into a Docker container? Perhaps from a pre-start task? The artifact stanza does not seem built for accessing local files.

3

I found an example of traversing parent directories in order to reach into the alloc/ directory.

    task "app" {
      driver = "docker"
      config {
        load  = "../../${NOMAD_ALLOC_DIR}/docker-image.tar"
        image = "docker-image"
      }
    }

This does seem to at least move me past one error, and into another:

open /var/lib/docker/tmp/docker-import-018997931/bin/json: no such file or directory

This may be just a problem with the image. I will need to verify the image is valid.

4

Yes, there was a problem with the image also. I rebuilt the image and then had a problem addressing the image as docker-image. That docker-image was just the name of the archive file. For the image config option I needed to specify the name that the image had been tagged with. I specified that and now we are golden.