`docker_tag` does not detect changes when the `docker_image` referenced by `source_image` changes about terraform-provider-docker

[carchi1a]

@labmonkey42 I fully agree that it would be nice for the docker_tag resource to have a triggers parameter that mimics the functionality of other resources like docker_image and docker_registry_image.

In the meantime, I managed to implement a workaround using Terraform's replace_triggered_by. If you're on Terraform >= 1.2 this might work for you too:

data "docker_registry_image" "upstream" {
  name = "registry1.example.org/ns/foo:latest"
}

resource "docker_image" "local" {
  name          = data.docker_registry_image.upstream.name
  pull_triggers = [data.docker_registry_image.upstream.sha256_digest]
}

resource "docker_tag" "server" {
  source_image = docker_image.local.name
  target_image = "registry2.example.org/ns/foo:success"

  lifecycle {
    replace_triggered_by = [
      docker_image.local.repo_digest
    ]
  }
}

resource "docker_registry_image" "push" {
  keep_remotely = true
  name          = docker_tag.server.target_image

  triggers = {
    source_image_hash = docker_tag.server.source_image_id
  }
}

Hope this helps!

[avbenavides]

Would be very nice to add a triggers property like docker_registry_image so it is revalidated against the sha, for example.
My workaround is to taint the tag but that of course is manual 🤮