List images in Google Container Registry in Java program - docker

Question

We wanted to list images and tags which names start with certain string. So far, we explored a few java lib (docker-java and spotify ones) and did quite amount of research, but still couldn't find a way out...
docker-java: 'com.github.docker-java', name: 'docker-java', version: '3.2.5'
The follow code lists images from public docker hub, not really the specified GCR. What's the right way to list image from our specified GCR?
DefaultDockerClientConfig config = DefaultDockerClientConfig
.createDefaultConfigBuilder()
.withRegistryUrl("http://eu.gcr.io/data-infrastructure-test-env")
.withDockerConfig("/home/me/.docker/config.json")
.build();
DockerClient dockerClient = DockerClientBuilder.getInstance(config).build();
List<SearchItem> items = dockerClient.searchImagesCmd("daas").exec();
List<String> images = new ArrayList<>();
for (SearchItem searchItem : items){
images.add(searchItem.getName());
}
Update - some progress
Inspired by this post: How to list images and tags from the gcr.io Docker Registry using the HTTP API?
I tried the following steps with my own google account, which has project owner (w/o firewall) permission:
gcloud auth login
gcloud auth print-access-token
define a function to get string for basic auth:
private String basicAuth(String username, String password) { return "Basic " + Base64.getEncoder().encodeToString((username + ":" + password).getBytes()); }
4, try the following code:
HttpRequest request = HttpRequest.newBuilder().uri(URI.create("https://gcr.io/v2/token?service=eu.gcr.io&scope=registry:my_gcp_project:*"))
.headers("Accept", "application/json"
, "Authorization",basicAuth("_token"
,"the_token_got_from_step_2"))
.GET()
.build(); UncheckedObjectMapper objectMapper = new UncheckedObjectMapper(); Map<String, String> response = HttpClient.newHttpClient()
.sendAsync(request, HttpResponse.BodyHandlers.ofString())
.thenApply(HttpResponse::body).thenApply(objectMapper::readValue)
.get();
String token = response.get("token");
request = HttpRequest.newBuilder().uri(URI.create("https://eu.gcr.io/v2/my_gcp_project/my_image/tags/list"))
.header("Authorization","Bearer " + token)
.GET().build(); String response2 = HttpClient.newHttpClient()
.sendAsync(request, HttpResponse.BodyHandlers.ofString())
.thenApply(HttpResponse::body)
.get();
However, the response2 I got was:
{"errors":[{"code":"UNAUTHORIZED","message":"Requested repository does not match bearer token resource: data-infrastructure-test-env/daas-master"}]}
Could you help to check what went wrong?

Answer 1

Docker engine API documentation clearly states that the ImageSearch command returns images from the Docker Hub registry: https://docs.docker.com/engine/api/v1.40/#operation/ImageSearch
For searching a GCR registry, you should rather use the Docker registry API.

Answer 2

Finally got it work!
I only need to change the second request uri to be: "https://eu.gcr.io/v2/my_gcp_project/tags/list" instead of "https://eu.gcr.io/v2/my_gcp_project/my_image/tags/list"
and I got some meaningful response back