Slack App to trigger GitHub Actions (aka SAGA)

This is a Pulumi Stack that creates an API Gateway endpoint with Lambda that triggers GitHub dispatch_workflow GitHub Actions.

• At least one argument to Slack's slash command is expected
• The first argument will be the event name, prefixed with saga-.
• The rest of the arguments are sent to GitHub Action inside the client_payload as args
• The output of this stack is an API endpoint that can be used as the receiving end of a Slack App Slash Command

How it works

Slack requires slash commands to be acknowledged within 3 seconds, otherwise Slackbot replies with "Something went wrong. Please try again!". To stay within that limit the stack deploys two Lambdas (Node.js 24):

• saga - verifies the Slack request signature, replies On it! immediately and invokes the worker asynchronously
• saga-worker - sends the repository_dispatch event to GitHub and reports failures back to the Slack user via the command's response_url

Deployment

Required Environment Variables

Read when running pulumi up and stored as Lambda environment variables. Deployment fails fast if any is missing.

• GITHUB_TOKEN - the GitHub token used to interact with GitHub Actions
• GITHUB_OWNER - GitHub owner of the repository holding the GitHub Action
• GITHUB_REPO - GitHub repository holding the GitHub Action
• SLACK_SIGNING_SECRET - the signing secret of the triggering Slack App (requests that fail signature verification are rejected with 401)

Outputs

endpoint - the endpoint to be set as the Slack App Slash Command target