Pushing to Azure Container Registry fails with "401 Unauthorized" even though "docker push" works

[chanseokoh]

Even though docker push francium25.azurecr.io/hello-world works, Jib cannot push to Azure Container Registry. Note Jib does retrieve Azure credentials from ~/.docker/config.json.

[INFO] Using credentials from Docker config (.../.docker/config.json) for francium25.azurecr.io/hello-world

Notably, ~/docker/config.json has identitytoken that other auths entries don't have. I wonder if this is basically the same issue we've taken care of when using Azure credential helpers (#1490).

    "auths": {
       "francium25.azurecr.io": {
            "auth": "...",
            "identitytoken": "..."
        },
        "quay.io": {
            "auth": "..."
        },

Full log:

[INFO] Containerizing application to francium25.azurecr.io/hello-world...
[WARNING] Base image 'gcr.io/distroless/java:8' does not use a specific image digest - build may not be reproducible
[INFO] Using credentials from Docker config (.../.docker/config.json) for francium25.azurecr.io/hello-world
[INFO] Using base image with digest: sha256:f59b26c5ecc735514a38afbf845214383c4e2ba1fdd15a76225339b8ab7da8ef
[INFO] Executing tasks:
[INFO] [=======                       ] 22.2% complete
[INFO] > pulling base image manifest
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.530 s
[INFO] Finished at: 2020-05-21T13:50:02-04:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal com.google.cloud.tools:jib-maven-plugin:2.2.0:build (default-cli) on project helloworld: Build image failed, perhaps you should make sure your credentials for 'francium25.azurecr.io/hello-world' are set up correctly. See https://github.com/GoogleContainerTools/jib/blob/master/docs/faq.md#what-should-i-do-when-the-registry-responds-with-unauthorized for help: Unauthorized for francium25.azurecr.io/hello-world: 401 Unauthorized -> [Help 1]