Make it possible to ignore changes to k8s deployment pod images

[dzhlobo]

Sometimes we deploy new images not via terraform but using kubectl:

kubectl -n $APP_NAME set image deployments/api *=$api_image_tag && \
kubectl -n $APP_NAME rollout status -w deployments/api

When we do this the next time we run terraform plan or apply it tries to reset image to the one from terraform config. It's possible to ignore by adding lifecycle block for kubernetes_deployment resource:

lifecycle {
  # we change image name during deployment outside of terraform
  ignore_changes = [
    spec[0].template[0].spec[0].container[0].image,
    spec[0].template[0].spec[0].init_container[0].image,
    spec[0].template[0].metadata[0].annotations["kubectl.kubernetes.io/restartedAt"]
  ]
}

If we do it right now it will no longer be possible to update image via terraform config and some app deploy via terraform.

It's not currently possible to make lifecycle dynamic in any way. Here's the issue about the problem: hashicorp/terraform#24188