I was having issues with configuring a docker agent in a declarative pipeline project, which I tracked down to an inconsistency with the way the configuration parameters are handled while pulling and running the image.

Given a configuration that includes this:

  agent {
    docker {
      registryUrl "https://my-project.nexus.mydomain.com"
      registryCredentialsId "myproject-registry-creds"
      image "myproject/build:latest"
    }
  }

I would expect to happen given this configuration would be something like this:

docker pull my-project.nexus.mydomain.com/myproject/build:latest
docker run ... my-project.nexus.mydomain.com/myproject/build:latest

What actually happens though, is this:

docker pull my-project.nexus.mydomain.com/myproject/build:latest
docker run ... myproject/build:latest

This means that even though the console logs showed the correct image being pulled, a different image was actually run.