query the image digest of a tag from the registry

Environment:

• Jib version: jib-core 0.11.0
• Build tool: maven 3.6
• OS: macos

Description of the issue:

Looking at https://github.com/GoogleContainerTools/jib/blob/master/jib-core/src/main/java/com/google/cloud/tools/jib/registry/ManifestPuller.java#L89-L94 the ManifestPuller doesn’t read the response header of Docker-Content-Digest to get the sha256 digest you can use and pass to tools like docker pull <image-name>@sha256:.... or kubectl set image deployment/name container=<image-name>@sha256... for CI/ CD purposes.

Expected behavior:

A new method getDigest() from the puller

Steps to reproduce: Run the following test:

public class RegistryTest {
    @Test
    public void registryDigest() throws IOException, RegistryException {
        RegistryClient.Factory factory = RegistryClient.factory(EventHandlers.NONE, "registry-1.docker.io", "library/centos");
        Authorization auth = factory.newRegistryClient().getRegistryAuthenticator().get().authenticatePull(null);
        factory.setAuthorization(auth);
        RegistryClient client = factory.newRegistryClient();

        V22ManifestListTemplate manifest = client.pullManifest("7", V22ManifestListTemplate.class);
        // If this gets stale, update by getting the output of
        // skopeo  inspect docker://centos:7 | jq '.Digest' -r
        Assertions.assertEquals("sha256:307835c385f656ec2e2fec602cf093224173c51119bbebd602c53c3653a3d6eb", manifest.getDigest());

        // These refer to other digests found in the manifest.json
//        Assertions.assertEquals("foo", manifest.getDigestsForPlatform("amd64", "linux"));
//        V22ManifestTemplate manifest = client.pullManifest("7", V22ManifestTemplate.class);
//        Assertions.assertEquals("foo", manifest.getContainerConfiguration().getDigest());
    }
}

Log output:

none, the code doesn’t compile

[tejaskasetty]

@chanseokoh I have made the changes. If its fine I will go ahead with making changes to the test cases.

[aespinosa]

thanks! i’ll keep note of that.