Can't get manifest plugin to work correctly (w/ 1.0RC1)

I want to generate a docker manifest in my pipeline. As I am using auto-tagging with the platform-specific images, the manifest should generate those versions (e.g. 0.9.3 / 0.9) as well.

Since this is not properly documented with the manifest plugin, I’ve tried it this way:

steps:
  - name: manifest
    image: plugins/manifest
    settings:
      target: my/image:${DRONE_TAG}
      template: my/image:${DRONE_TAG}-ARCH
      username:
        from_secret: docker_username
      password:
        from_secret: docker_password
      platforms:
        - linux/amd64
        - linux/arm

But it seems Drone won’t escape the variables inside the plugin settings.

My second approach was to use a manifest template with the spec and auto_tag options, so the config looks like this:

steps:
  - name: manifest
    image: plugins/manifest
    settings:
      spec: manifest.tmpl
      auto_tag: true
      username:
        from_secret: docker_username
      password:
        from_secret: docker_password
      platforms:
        - linux/amd64
        - linux/arm

This is not properly documented as well, so I took the template I found in the plugin’s repository and adjusted it slightly for my image name. Using that, I get the following output in the manifest step:

2018/11/17 00:19:10 pushing by spec
time="2018-11-17T00:19:10Z" level=fatal msg="Can't unmarshal YAML file \"/drone/src/manifest-014888304\": yaml: mapping values are not allowed in this context" 
2018/11/17 00:19:10 exit status 1

What is the right way to do this?

I’d recommend opening an issue in the repository to get some help (the plugin author does not use discourse and won’t see this). I also had trouble figuring out how to use this plugin, and think it would benefit from some documentation and maybe some UX improvements.

Thanks, I opened an issue.