Google Container Registry Service Account Permissions

21046548While testing Jenkins X I hit an issue that puzzled me. I use Kaniko to build Docker images and push them into Google Container Registry. But the push to GCR was failing with

INFO[0000] Taking snapshot of files...
error pushing image: failed to push to destination gcr.io/myprojectid/croc-hunter:1: DENIED: Token exchange failed for project 'myprojectid'. Caller does not have permission 'storage.buckets.get'. To configure permissions, follow instructions at: https://cloud.google.com/container-registry/docs/access-control

During installation Jenkins X creates a GCP Service Account based on the name of the cluster (in my case jx-rocks) called jxkaniko-jx-rocks with roles:

  • roles/storage.admin
  • roles/storage.objectAdmin
  • roles/storage.objectCreator

More roles are added if you install Jenkins X with Vault enabled.

A key is created for the service account and added to Kubernetes as secrets/kaniko-secret containing the service account key json, which is later on mounted in the pods running Kaniko as described in their instructions.

After looking and looking the service account and roles they all seemed correct in the GCP console, but the Kaniko build was still failing. I found a stackoverflow post claiming that the permissions were cached if you had a previous service account with the same name (WAT?), so I tried with a new service account with same permissions and different name and that worked. Weird. So I created a script to replace the service account by another one and update the Kubernetes secret.

ACCOUNT=jxkaniko-jx-rocks
PROJECT_ID=myprojectid

# delete the existing service account and policy binding
gcloud -q iam service-accounts delete ${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com
gcloud -q projects remove-iam-policy-binding ${PROJECT_ID} --member=serviceAccount:${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com --role roles/storage.admin
gcloud -q projects remove-iam-policy-binding ${PROJECT_ID} --member=serviceAccount:${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com --role roles/storage.objectAdmin
gcloud -q projects remove-iam-policy-binding ${PROJECT_ID} --member=serviceAccount:${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com --role roles/storage.objectCreator

# create a new one
gcloud -q iam service-accounts create ${ACCOUNT} --display-name ${ACCOUNT}
gcloud -q projects add-iam-policy-binding ${PROJECT_ID} --member=serviceAccount:${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com --role roles/storage.admin
gcloud -q projects add-iam-policy-binding ${PROJECT_ID} --member=serviceAccount:${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com --role roles/storage.objectAdmin
gcloud -q projects add-iam-policy-binding ${PROJECT_ID} --member=serviceAccount:${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com --role roles/storage.objectCreator

# create a key for the service account and update the secret in Kubernetes
gcloud -q iam service-accounts keys create kaniko-secret --iam-account=${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com
kubectl create secret generic kaniko-secret --from-file=kaniko-secret

And it did also work, so no idea why it was failing, but at least I’ll remember now how to manually cleanup and recreate the service account.

2 thoughts on “Google Container Registry Service Account Permissions

  1. Container Registry only recognizes permissions set on the Cloud Storage bucket. Container Registry will ignore permissions set on individual objects within the Cloud Storage bucket.

  2. Thanks for this! I’ve also got a gist that has a bit more detail on the issue and the fix.

    GCP cached permissions issue

    GCP has an issue which surfaces when service accounts are recreated with the same name but without the old policies being removed. It is confusing because the GUI and CLI will show that permissions are there and it will even let you re-add them BUT, anytime you try to do something that requires the permissions it won’t work. For example, if you try to push an image it may say that you don’t have storage.buckets.get even thought everything shows that you are part of storage.admin.

    Reproducing the issue

    Set the values to match your environment

    export ACCOUNT=<service-account>
    export PROJECT_ID=<project-id>
    export IMAGE_NAME=gcr.io/$PROJECT_ID/your-image:your-tag
    

    Create a service account with the required permissions and generate a key for it. Let’s create a script called create.sh that does exactly that.

    gcloud -q iam service-accounts create ${ACCOUNT} --display-name ${ACCOUNT}
    gcloud -q projects add-iam-policy-binding ${PROJECT_ID} --member=serviceAccount:${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com --role roles/storage.admin
    gcloud iam service-accounts keys create key.json \
      --iam-account ${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com
    gcloud projects get-iam-policy ${PROJECT_ID}  \
    --flatten="bindings[].members" \
    --format='table(bindings.role)' \
    --filter="bindings.members:${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com"
    

    When we run the script we will see the expected permissions

    ROLE
    roles/storage.admin
    

    Now let’s just check that an image can be pushed

    docker login -u _json_key -p "$(cat key.json)" https://gcr.io
    docker push $IMAGE_NAME
    

    Cool. It worked. Ok, now let’s delete the account and re-run create.sh

    gcloud -q iam service-accounts delete ${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com
    ./create.sh
    

    That’s odd, now when we re-run docker login -u _json_key -p "$(cat key.json)" https://gcr.io && docker push $IMAGE_NAME it is failing with the following issue.

    denied: Token exchange failed for project '****'. Caller does not have permission 'storage.buckets.get'. To configure permissions, follow instructions at: https://cloud.google.com/container-registry/docs/access-control
    

    But it shows that we have the right permissions in the GUI and in the CLI!!!

    Fixing the issue

    The issue is caused by the old permission hanging around. In fact, even if we re-create the service account and don’t add any permissions, the old permissions show in the GUI and CLI. And if we try to add the permission, it will allow it but it won’t actually be applied.

    To fix, we have to make sure we delete the service and remove the permissions before we recreate it.

    gcloud -q iam service-accounts delete ${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com
    gcloud -q projects remove-iam-policy-binding ${PROJECT_ID} --member=serviceAccount:${ACCOUNT}@${PROJECT_ID}.iam.gserviceaccount.com --role roles/storage.admin
    

    After the above is ran we can re-run create.sh, wait for about 10 seconds and then try to login and push (i.e. docker login -u _json_key -p "$(cat key.json)" https://gcr.io && docker push $IMAGE_NAME), it will be successful. If not, wait a bit longer and do the push again, it will work.

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