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Terraform/OpenTofu via Pull Request (TF-via-PR)

What does it do?	Who is it for?
Plan and apply changes with CLI arguments and encrypted plan file to avoid configuration drift. Outline diff changes within updated PR comment and matrix-friendly workflow summary, complete with log.	DevOps and Platform engineers wanting to empower their teams to self-service scalably. Maintainers looking to secure their pipeline without the overhead of containers or VMs.

View: Usage Examples · In/Output Parameters · Security · Changelog · License

Usage

How to get started quickly?

on:
  pull_request:
  push:
    branches: [main]

jobs:
  provision:
    runs-on: ubuntu-latest

    permissions:
      actions: read        # Required to identify workflow run.
      checks: write        # Required to add status summary.
      contents: read       # Required to checkout repository.
      pull-requests: write # Required to add comment and label.

    steps:
      - uses: actions/checkout@4
      - uses: hashicorp/setup-terraform@v3
      - uses: devsectop/tf-via-pr@v12
        with:
          # Run plan by default, or apply with lock on merge.
          command: ${{ github.event_name == 'push' && 'apply' || 'plan' }}
          arg-lock: ${{ github.event_name == 'push' }}
          arg-var-file: env/dev.tfvars
          arg-workspace: dev-use1
          working-directory: path/to/directory
          plan-encrypt: ${{ secrets.PASSPHRASE }}

Tip

• All supported arguments (e.g., -backend-config, -destroy, -parallelism, etc.) are listed below.
• Environment variables can be passed in for cloud platform authentication (e.g., configure-aws-credentials for short-lived credentials).

Where to find more examples?

The following workflows showcase common use cases, while a comprehensive list of inputs is documented below.

Run on pull_request (plan) and push (apply) events with Terraform, AWS authentication and caching.	Run on pull_request (plan) and merge_group (apply) events with OpenTofu in matrix strategy.
Run on pull_request (plan) and push (apply) events with conditional job stages based on plan file.	Run on schedule (cron) event with -refresh-only to open an issue on configuration drift.
Run on pull_request (plan) and push (apply) events with fmt/validate checks and TFLint.	Run on pull_request (plan or apply) event with Terraform and OpenTofu on self-hosted runner.

How does encryption work?

Before the workflow uploads the plan file as an artifact, it can be encrypted with a passphrase (e.g., ${{ secrets.PASSPHRASE }}) to prevent exposure of sensitive data using plan-encrypt input. This is done with OpenSSL's symmetric stream counter mode encryption with salt and pbkdf2.

In order to decrypt the plan file locally, use the following commands after downloading the artifact (noting the whitespace before openssl to prevent recording the command in shell history):

unzip <tf.plan>
 openssl enc -aes-256-ctr -pbkdf2 -salt -in <tf.plan> -out tf.plan.decrypted -pass pass:"<passphrase>" -d
<tf.tool> show tf.plan.decrypted

For each workflow run, a matrix-friendly job summary with logs is added as a fallback to the PR comment. Below this, you'll find a list of plan file artifacts generated during runtime.

Parameters

Inputs - Configuration

Type	Name	Description
CLI	command	Command to run between: plan or apply. Optionally init for checks and outputs only. Example: plan
CLI	working-directory	Specify the working directory of TF code, alias of arg-chdir. Example: path/to/directory
CLI	tool	Provisioning tool to use between: terraform or tofu. Default: terraform
Check	format	Check format of TF code. Default: false
Check	validate	Check validation of TF code. Default: false
Check	plan-parity	Replace the plan file if it matches a newly-generated one to prevent stale apply (very rarely needed nowadays). Default: false
Security	plan-encrypt	Encrypt plan file artifact with the given input. Example: ${{ secrets.PASSPHRASE }}
Security	token	Specify a GitHub token. Default: ${{ github.token }}
UI	comment-pr	PR comment by: update existing comment, recreate and delete previous one, or none. Default: update
UI	label-pr	Add a PR label with the command input. Default: true
UI	hide-args	Hide comma-separated list of CLI arguments from the command input. Default: detailed-exitcode,lock,out,var=
UI	show-args	Show comma-separated list of CLI arguments in the command input. Default: workspace

The default behavior of comment-pr is to update the existing PR comment with the latest plan output, making it easy to track changes over time through the comment's revision history.

Inputs - Arguments

Note

• Arguments are passed to the appropriate TF command(s) automatically, whether that's init, workspace, validate, plan, or apply.
  
• For repeated arguments like arg-var, arg-backend-config, arg-replace and arg-target, use commas to separate multiple values (e.g., arg-var: key1=value1,key2=value2).

Toggle view of all available CLI arguments.

Name	CLI Argument
arg-auto-approve	-auto-approve
arg-backend-config	-backend-config
arg-backend	-backend
arg-backup	-backup
arg-chdir	-chdir
arg-check	-check Default: true
arg-compact-warnings	-compact-warnings
arg-concise	-concise
arg-destroy	-destroy
arg-detailed-exitcode	-detailed-exitcode Default: true
arg-diff	-diff Default: true
arg-force-copy	-force-copy
arg-from-module	-from-module
arg-generate-config-out	-generate-config-out
arg-get	-get
arg-list	-list
arg-lock-timeout	-lock-timeout
arg-lock	-lock
arg-lockfile	-lockfile
arg-migrate-state	-migrate-state
arg-no-tests	-no-tests
arg-or-create	-or-create Default: true
arg-parallelism	-parallelism
arg-plugin-dir	-plugin-dir
arg-reconfigure	-reconfigure
arg-recursive	-recursive Default: true
arg-refresh-only	-refresh-only
arg-refresh	-refresh
arg-replace	-replace
arg-state-out	-state-out
arg-state	-state
arg-target	-target
arg-test-directory	-test-directory
arg-upgrade	-upgrade
arg-var-file	-var-file
arg-var	-var
arg-workspace	-workspace
arg-write	-write

Outputs

Type	Name	Description
Artifact	plan-id	ID of the plan file artifact.
Artifact	plan-url	URL of the plan file artifact.
CLI	command	Input of the last TF command.
CLI	diff	Diff of changes, if present (truncated).
CLI	exitcode	Exit code of the last TF command.
CLI	result	Result of the last TF command (truncated).
CLI	summary	Summary of the last TF command.
Workflow	check-id	ID of the check run.
Workflow	comment-id	ID of the PR comment.
Workflow	job-id	ID of the workflow job.
Workflow	run-url	URL of the workflow run.
Workflow	identifier	Unique name of the workflow run and artifact.

Security

View security policy and reporting instructions.

Tip

Pin your workflow version to a specific release tag or SHA to harden your CI/CD pipeline security against supply chain attacks.

Changelog

View all notable changes to this project in Keep a Changelog format, which adheres to Semantic Versioning.

Tip

All forms of contribution are very welcome and deeply appreciated for fostering open-source projects.

• Create a PR to contribute changes you'd like to see.
• Raise an issue to propose changes or report unexpected behavior.
• Open a discussion to discuss broader topics or questions.
• Become a stargazer if you find this project useful.

To-Do

• Handling of inputs which contain space(s) (e.g., working-directory: path to/directory).
• Handling of comma-separated inputs which contain comma(s) (e.g., arg-var: token=1,2,3)—use TF_CLI_ARGS workaround.

License

• This project is licensed under the permissive Apache License 2.0.
• All works herein are my own, shared of my own volition, and contributors.
• Copyright 2022-2024 Rishav Dhar — All wrongs reserved.