Gabriel Petrovay February 2016

How to list the published container images in the Google Container Registry using gcloud or another CLI

Is there a gcloud API or other command line interface (CLI) to access the list of published container images in the private Google Container Registry? (That is the container registry inside a Google Cloud Platform project)

gcloud container does not seem to help:

$ gcloud container
Usage: gcloud container [optional flags] <group | command>
  group may be           clusters | operations
  command may be         get-server-config

Deploy and manage clusters of machines for running containers.

flags:
  --zone ZONE, -z ZONE   The compute zone (e.g. us-central1-a) for the cluster

global flags:
  Run `gcloud -h` for a description of flags available to all commands.

command groups:
  clusters               Deploy and teardown Google Container Engine clusters.
  operations             Get and list operations for Google Container Engine
                         clusters.

commands:
  get-server-config      Get Container Engine server config.

I also don't want to use gcloud docker to list images because this wants to connect to a particular docker daemon that I don't have. Unless there is a way to tell gcloud docker to connect to a remote public docker daemon that can read the private containers pushed to the registry through my project.

Answers


Robert Bailey February 2016

If you know the project that is hosting the images (e.g. google-containers) you can list images with

gcloud docker search gcr.io/google_containers

For an individual image (e.g. the pause image in the google-containers project), you can check the versions with

curl https://gcr.io/v2/google-containers/pause/tags/list


Nick February 2016

The answer given by Robert Bailey is good for certain tasks, but might be missing what you specifically want to do. Nonetheless, your comments in reply to his answer are not so much faults of his answer as of your own understanding of what the commands which "fail" actually mean to do.

As far as your second comment,

Using docker I get the following error (for the reasons mentioned above; I also edited the question): Cannot connect to the Docker daemon. Is the docker daemon running on this host?

This is a result of the docker daemon not running. Check if it's running via ps aux | grep docker. You can refer to the Docker documentation to determine how to properly install and run it.

As far as your first comment,

Using curl I get: {"errors":[{"code":"DENIED","message":"Failed to read tags for repository '<my_project>/<my_image>'"}]}. I have to authenticate somehow to access the images in a private registry. I don't want to use docker because that means I have to have a docker daemon available. I only want to see if a container image with a particular version is in the Container Registry. So what I need is an API to the Container Registry in the Google Developer Console.

You wouldn't be able to curl the image unless it was public, as mentioned in Robert's latest comment, or unless you somehow provided some great oauth headers during the curl's invocation.

You should use gcloud docker to attempt to list the images in the registry, as you would for other docker registries. The gcloud container command group is the wrong one for your desired task. You can see below an output from gcloud version 96.0.0 (latest as of this comment) for the docker command group:

 


Gabriel Petrovay February 2016

My best solution so far without having a local docker available and without being able to connect to a remote docker (this would still require at least the local docker client but not the local daemon running), is to SSH into a Container Cluster instance that runs docker and have my search done there and getting the result in my original script:

gcloud compute ssh <container_cluster_instance> -C "sudo gcloud docker search ..."

Of course, to avoid all verbose output (like SSH/Terminal welcome messages) I use some arguments to silent the execution a bit:

gcloud compute ssh --ssh-flag="-q" "$INSTANCE_NAME" -o LogLevel=quiet -C "sudo gcloud docker search ..."

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Asked in February 2016
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