Allow passing custom arguments from Atlantis command to Atlantis.yaml - use case for custom init arguments.

[mechastorm]

Problem

This feature will help my team integrate our existing terraform projects with Atlantis with minimal changes.

We currently use the env/{env}.tfvars project structure with the addition of a env/{env}.backend.tfvars for unique remote backend configs per environments.

.
├── env
│   ├── production.tfvars
│   ├── production.backend.tfvars
│   ├── staging.tfvars
│   └── staging.backend.tfvars
└── main.tf

In our workflow, when we do terraform init, it will be

terraform init -backend-config=production.backend.tfvars

Currently Atlantis does not seem to able to support this structure.

Wish

Be able to initialize a custom backend config file from the atlantis command.

Suggestion

Utilizing the atlantis.yaml config, I could in theory have a config like

extra_arguments:
  - command_name: init
    arguments:
    - "-backend-config=env/${MY_ENV_NAME}.backend.tfvars "
  - command_name: plan
    arguments:
    - "-var-file=env/${MY_ENV_NAME}.tfvars "

Then in an MR/PR, I can run the atlantis command (in theory)

atlantis plan --extra-args="MY_ENV_NAME=staging"

I believe this feature would allow users extra flexibility as well in doing additional custom hooks with the atlantis.yaml config.

[lkysow]

Closed by #152. In version 0.4 now.

To accomplish this you need to define each "project" in your repo in an atlantis.yaml file at the root and then create a separate workflow for staging/prod:

# atlantis.yaml
version: 2
projects:
- name: staging
  dir: .
  workflow: staging
- name: production
  dir: .
  workflow: production
workflows:
  production:
    plan:
      steps:
      - run: rm -rf .terraform # Otherwise terraform will get confused.
      - init:
          extra_args: [-backend-config=env/production.backend.tfvars]
      - plan:
          extra_args: [-var-file=env/production.tfvars]
  staging:
    plan:
      steps:
      - run: rm -rf .terraform
      - init:
          extra_args: [-backend-config=env/staging.backend.tfvars]
      - plan:
          extra_args: [-var-file=env/staging.tfvars]

Atlantis will automatically run plan now so you won't be needing this as much but to run plan for staging you need to use the project name and the -p flag:

atlantis plan -p staging

To apply:

atlantis apply -p staging