Get so i can depend on a destroy

[squeedee]

In my pipeline, i want to ensure the stack is removed before redeploying it, i'd like something like:

  - name: purge-previous-deployment
    plan:
      - get: environment
        trigger: true
        passed: [claim-environment]
      - get: appdog-ci
      - put: opsman-terraform
        params:
          action: destroy
          env_name: {{environment-name}}
        get_params:
          action: destroy

  - name: create-deployment
    plan:
      - get: opsman-terraform
        trigger: true
        passed: [purge-previous-deployment]
      - get: appdog-ci
      - put: opsman-terraform
        params:
          env_name: {{environment-name}}

[ljfranklin]

@squeedee After thinking about it for a bit, I think this can be done by adding a "destroyed" field to the version:

type Version struct {
    LastModified string `json:"last_modified"`
    EnvName      string `json:"env_name"`
    Destroyed    bool   `json:"destroyed"`
}

This way the get knows to no-op if it's been told to fetch a destroyed environment, but can still error if it's been told to fetch an environment that never existed or was destroyed out of band.

In the meantime, you can workaround this by doing the destroy and create in the same job:

- name: create-deployment
  plan:
    - get: environment
       trigger: true
       passed: [claim-environment]
    - put: opsman-terraform
      params:
        action: destroy
        env_name: {{environment-name}}
      get_params:
        action: destroy
    - get: appdog-ci
    - put: opsman-terraform
      params:
        env_name: {{environment-name}}

[ljfranklin]

@squeedee still thinking about this, but I'm leaning towards waiting until Concourse resource delete actions become a first-class thing. There's a long thread around overhauling the resource interface that discusses delete among other things: concourse/concourse#534.

I already hacked around the lack of a delete with put.get_params.action: delete. I feel like adding a new version on delete might be a step in the wrong direction long-term. Interested to hear what others think though.

[ljfranklin]

@squeedee Going to close this out as won't fix for now. Once Concourse adds an actual delete call (concourse/concourse#534) you won't be able to trigger off a delete as it actually deletes a set of versions rather than adding a new "deleted" version.