Feature Proposal - workflow-level `env` values

[0xch4z]

Problem

Currently the only way to dynamically configure your environment for running a workflow is by using the special env and multienv steps in your plan and apply configuration respectively.

I've found there is very rarely a case where the same environment variables needed to run terraform plan aren't also needed in when running terraform apply, meaning you must duplicate your environment configuration in two places.

While framing environment configuration as an imperative "step" is neat, most of the time order doesn't matter. Additionally, when you have a need for many environment variables to be set based on complex commands, this becomes unmaintainable.

I guess there is the argument that multienv can be used to execute a script to carry out the complex environment setup, but duplication across both of plan and apply is still needed and maintaining a large script pulling values from various places is less than ideal.

Proposed Solution

Allow specifying environment variable bindings at a workflow-level. This means that there is an implicit env step preceding any steps in both the plan and apply steps.

workflows:
  staging:
    env:
    - name: MY_ENV_VAR1
      command: my-env-var1-command
    - name: MY_ENV_VAR2
      command: my-env-var2-command

[vveliev-tc]

I'm not sure if this can help, but as an alternative solution you may just run a script before plan/apply

when .terraformrc is executed it's calling different files based on the namespace and stage. You should be able to load default environment variables this way as well

    plan:
      steps:
      - env:
          name: STAGE
          command: echo ${PROJECT_NAME} | cut -d '_' -f 2-
      - env:
          name: NAMESPACE
          command: echo ${PROJECT_NAME} | cut -d '-' -f 2- | cut -d '_' -f 1
      - env:
          name: COMMENT_ARGS
          command: echo "${COMMENT_ARGS//\\/}" | tr ',' ' '
      - run: rm -rf .terraform/* && rm -rf .terraform.lock*
      - run: git config --global credential.helper git-credential-helper.sh
      - run: >-
          source .terraformrc &&
          terraform init -input=false -no-color &&
          terraform workspace select ${STAGE} &&