terraform-provider-docker

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This issue was originally opened by @schlitzered as https://github.com/hashicorp/terraform-provider-docker/issues/139. It was migrated here as a result of the community provider takeover from @kreuzwerker. The original body of the issue is below.

---

Terraform Version

Terraform v0.11.13

• provider.docker v1.1.1

Affected Resource(s)

docker_container

Terraform Configuration Files

resource "docker_container" "fdsafx_dev" {
  image   = "${docker_image.fdsafx_dev.latest}"
  name    = "fdsafx_dev"
  privileged = true
  entrypoint = [
    "/usr/sbin/init"
  ]
  volumes = {
    volume_name    = "www_fdsafx_test"
    read_only      = false
    host_path = "/Users/MyUser/tmp/docker_fdsafx/terraform/blarg/"
    container_path = "/www/fdsafx_test"
  }
}

Expected Behavior

container should have /Users/MyUser/tmp/docker_fdsafx/terraform/blarg/ mounted

Actual Behavior

container has /var/lib/docker/volumes/www_fdsafx_test/_data mounted

Steps to Reproduce

1. terraform apply

Important Factoids

running on MacOS useing Docker Desktop

from docker inspect:

        "Mounts": [
            {
                "Type": "volume",
                "Name": "www_fdsafx_test",
                "Source": "/var/lib/docker/volumes/www_fdsafx_test/_data",
                "Destination": "/www/fdsafx_test",
                "Driver": "local",
                "Mode": "rw",
                "RW": true,
                "Propagation": ""
            }
        ],

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days. If you don't want this issue to be closed, please set the label pinned.

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days. If you don't want this issue to be closed, please set the label pinned.

In case anyone runs into this issue, as a work-around, it seems that removing volume_name allows host_path to work.

This issue could be fixed by disallowing both volume_name and host_path to be set since setting both doesn't make sense (a host path can't be named).

In case anyone runs into this issue, as a work-around, it seems that removing volume_name allows host_path to work.

This issue could be fixed by disallowing both volume_name and host_path to be set since setting both doesn't make sense (a host path can't be named).

Following this approach solved this for me.

I read the official docker docs and looked into the provider codebase and found out what the problem is. According to https://docs.docker.com/engine/reference/run/#volume-shared-filesystems when creating a volume

The host-src can either be an absolute path or a name value. If you supply an absolute path for the host-src, Docker bind-mounts to the path you specify. If you supply a name, Docker creates a named volume by that name.

To separate this "union" type in this provider, two values got introduced: volume_name and host_path. And @mafredri was right: having both should not be possible.

The code actually is:

volumeName := volume["volume_name"].(string)
if len(volumeName) == 0 {
  volumeName = volume["host_path"].(string)
}

which leads to the case, that as soon as the volume_name is set, the host_path does not matter. (I assume that some users think that volume_name is simply an internally used value and set both. I would do that as well, to be honest).

How to fix:

• We could introduce a mechanisms (ConflictsWith) which checks whether both values are set and, if so it errors.
• Or we simply assume that when host_path is set and prioritize its value
• We move away from the two-values system and simply use a host-src, the same way as the docker documentation describes it, and simply pass the value do the docker client

I don't like option 2, and I think option 1 & 3 migh be breaking changes which would first need a warning with a new minor version and then the change with the major version. However, I am not sure whether option 1 would really be a breaking change..

Any opinions of the people affected by this bug?

I would prefer option 1 with a link to docs that describe you can not use both of them at the same time.