I am trying to build, sign, and push a multi-arch container image using a Harbor registry with Notary. Following the steps in https://www.cncf.io/blog/2021/07/28/enforcing-image-trust-on-docker-containers-using-notary/ I was able to get the simple example working with DOCKER_CONTENT_TRUST_SERVER
pointing to the URL of my notary server.
However, when I try to build and push a multi-arch image, I do not get prompted about the trust metadata and it seems to completely skip the signing step. The command I'm running to build and push the multi-arch image is:
docker buildx build --file Dockerfile --push --platform linux/arm64,linux/amd64 --tag myharborregistry.com/myimage:latest .
Is there some extra step required to enable Docker Content Trust with buildx
? Perhaps there is a flag that I am missing or some additional configuration needed for the builder?