action.yaml

name: Review terraform plan

branding:
  icon: 'map'  
  color: 'purple'

description: >
  Run and cleanup terraform plan output, store it into an output to allow reviewing it.

inputs:
  terraform-environment:
    description: >
      Terraform environment, used to load corresponding var file named
      <terraform-environment>.tfvars into the working directory.
    required: true
    default: "preproduction"
  working-directory:
    description: working directory
    required: true
    default: "."
  terraform-plan-output:
    description: >
      Path of the plan file, to be used by the action "Apply terraform plan".
    default: "/tmp/plan.tfplan"
    required: false

outputs:
  plan-details:
    description: >
      Clean terraform plan, in HTML format, ready to integrate in a comment of
      corresponding pull request.
    value: ${{ steps.plan.outputs.plan-details }}

runs:
  using: "composite"
  steps:
    - id: plan
      name: terraform plan for review
      shell: bash
      working-directory: ${{ inputs.working-directory }}
      run: |
        echo "🗺 terraform plan -lock=false -var-file=${{ inputs.terraform-environment }}.tfvars --out ${{ inputs.terraform-plan-output }}"
        plan=$(terraform plan -lock=false -no-color -var-file=${{ inputs.terraform-environment }}.tfvars --out ${{ inputs.terraform-plan-output }})
        title=$(
          echo -e $(echo -e "$plan" | grep -e '^Plan:' || echo -e "") | \
          sed -E 's|Plan:||'
        )

        echo "🧹 remove plan noise"
        tf_plan=$(
          echo -e "$plan" | \
          tail -n +$(
            echo -e "$plan" | \
            grep -nE 'Terraform will perform the following actions|No changes. Infrastructure is up-to-date|No changes. Your infrastructure matches the configuration' | \
            cut -d':' -f1
          )
        )

        echo "📝 generate drift details"
        driftSeparatorLineNumber=$(
            echo -e "$plan" | \
            grep -nE 'Terraform detected the following changes made outside of Terraform' | cut -d':' -f1
          ) || true

        if [ -z "$driftSeparatorLineNumber" ]; then
          echo "🚫 no drift detected"
          drift=""
        else
          drift=$(
            echo -e "$plan" | \
            tail -n +$driftSeparatorLineNumber | sed '1,/─────────────────────────────────────────────────────────────────────────────/!d' | head -n -2
          )
        fi
        
        echo "🎁 wrap plan into HTML"
        message=$(printf "
          <details>
          <summary><b>Terraform plan:</b> %s %s</summary>

          \`\`\`hcl
          %s
          \`\`\`

          </details>
        
          <details>
          <summary><b>Terraform drift:</b> %s</summary>

          \`\`\`hcl
          %s
          \`\`\`

          </details>
        " "${title:-No changes. Infrastructure is up-to-date.}" "$(git rev-parse --short $GITHUB_SHA)" "$tf_plan" "$(git rev-parse --short $GITHUB_SHA)" "$drift")

        echo "👨‍💻 display plan"
        echo -e "$tf_plan"
        echo "" 
        echo "👨‍💻 display drift"
        echo -e "$drift"
        echo ""
        echo 'plan-details<<EOF' >> $GITHUB_OUTPUT
        echo "$message" >> $GITHUB_OUTPUT
        echo 'EOF' >> $GITHUB_OUTPUT