feat(plugins/docker): add docker-ref plugin

[denysvitali]

The docker-pull plugin really pulls the image in the case of On Demand Runners. Since we do require there a docker.AccessInfo, we can't avoid pulling the image (because HasRegistry automatically becomes true, and not providing a registry causes an error).

To avoid patching docker-pull further, a docker-ref is created. This is only used in the very specific case where a docker-pull can't be used because all of the following conditions are met:

• Access to the registry is not available
• On-Demand Runner (ODR) is being used

As a solution, this plugin allows you to be a sort of "noop" that adds a reference to a pre-built
Docker image (e.g: in an external CI) in the build stage.

---

Example usage:

app "whoami" {
  build {
    use "docker-ref" {
      image = "traefik/whoami"
      tag   = "latest"
    }
  }

  deploy {
    use "kubernetes" {
      // ...
    }
  }
}

[paladin-devops]

This is looking awesome! The website docs should definitely include the documentation for this plugin as well. 😄

I just tried this out locally with Docker and it worked great! Giving it a shot with ODRs next.

[paladin-devops]

This plugin also works with ODRs! 🎉

$ waypoint build                 

» Building docker-ref-nodejs...
  Performing operation on "docker" with runner profile "docker-01GDHSV8JJ6X6GS4XBGHQ6YG7V"

» Cloning data from Git
  URL: https://github.com/hashicorp/waypoint-examples
  Ref: nomad-remote-ops

» Downloading from Git
  Git Commit: 28f79b1f31ff630a10187295431adfca07be0b33
   Timestamp: 2022-09-29 22:12:49 +0000 UTC
     Message: Add example for docker-ref plugin.
  
✓ Running build v1
✓ Using Docker image in remote registry: hashicorp/waypoint:latest
✓ Running push build v1

Created artifact v1

» Variables used:
  VARIABLE | VALUE | TYPE | SOURCE  
-----------+-------+------+---------

$ waypoint artifact list-builds

» docker-ref-nodejs
    | ID | WORKSPACE |  BUILDER   |    STARTED     |   COMPLETED    | PIPELINE  
----+----+-----------+------------+----------------+----------------+-----------
  ✔ |  1 | default   | docker-ref | 54 seconds ago | 54 seconds ago |           

$ waypoint artifact list       

» docker-ref-nodejs
    | ID |  REGISTRY  | DETAILS |    STARTED     |   COMPLETED     
----+----+------------+---------+----------------+-----------------
  ✔ |  1 | docker-ref | build:1 | 57 seconds ago | 57 seconds ago  

[paladin-devops]

@denysvitali I think the last thing we need to do here is get the documentation generated! As mentioned elsewhere, make gen/website-mdx will take care of this for you. I should also add that since this is a new plugin, you won't see the files in the diff, and you'll need to git add each of the .mdx files generated in website/content/partials/components for docker-ref.

Once they're added to the repo, the other required change to get the documentation to appear on the website is in website/content/plugins/docker.mdx. There, you should add @include "components/builder-docker-ref.mdx", so the content will be displayed for the builder plugin!

https://github.com/swisscom/waypoint/blob/3b2731519929713eb52a632aa856b9d52647d4ed/website/content/plugins/docker.mdx?plain=1#L12-L20

[paladin-devops]

@denysvitali thanks for adding the docs, this is a great plugin! 😄 🐋 💰