Static site builds with GitHub Actions and GraphCMS

In this blog post I'd like to show you how to trigger a GitHub Actions Workflow from GraphCMS to deploy your static site with the latest content.

As GitHub requires a specific payload we need to set a small function between GraphCMS and GitHub.

This example uses AWS Lambda for the serverless function and Amazon S3 for storage. Of course you can use the cloud provider of your choice.

Overview - What we need to do

1. GitHub Actions workflow
2. GitHub access token
3. Lambda function
4. GraphCMS webhook
5. Test it!

1. GitHub Workflow

Our workflow should build the static recourses and deploy them. We use Gatsby as static site generator. So our workflow should be straightforward. The only special one is the trigger workflow_dispatch. More about this later.

name: Deploy on GraphCMS Publish Event

on: [workflow_dispatch]

jobs:
  build:
    name: Build
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Use Node.js
        uses: actions/setup-node@v1
        with:
          node-version: '12.x'
      - run: yarn install
      - run: yarn lint
      - run: yarn test
      - run: yarn build
      - uses: actions/upload-artifact@v2
        with:
          name: public
          path: public/
 deploy:
    name: Deployment
    runs-on: ubuntu-latest
    needs: [build]
    steps:
      - uses: actions/checkout@v2
      - name: Use Node.js
        uses: actions/setup-node@v1
        with:
          node-version: '12.x'
      - uses: actions/download-artifact@v2
        with:
          name: public
          path: public/
      - run: yarn install
      - run: yarn serverless:deploy

2. GitHub Access Token

To trigger our workflow from 'outside' we need to create a personal access token on GitHub.

Login to GitHub and goto https://github.com/settings/tokens. Create a new token and save it anywhere secure, we will need it later.

3. Lambda function

Our Lambda function will be called by the GraphCMS webhook. The function then will call the GitHub API and trigger our GitHub workflow.
We will call the worklow_dispatch endpoint which we use as trigger in our GitHub workflow in step 1. (GitHub Docs)

const axios = require('axios')

exports.handler = async (event) => {
  const { status } = await axios.post(
    'https://api.github.com/repos/[OWNER]/[REPO]/actions/workflows/[WORKFLOW-FILENAME]/dispatches',
    { ref: 'master' },
    {
      headers: {
        Accept: 'application/vnd.github.v3+json',
        Authorization: `Bearer ${process.env.GITHUB_TOKEN}`,
      }
    }
  )

  if (status === 204) {
    return {
      statusCode: 200,
      body: 'GitHub API called'
    }
  }

  return {
    statusCode: 400
  }
}

You will have to change [OWNER], [REPO] and [WORKFLOW-FILENAME] with your data. The GitHub token we created in step 2 is stored as an environment variable (process.env.GITHUB_TOKEN).

Parameter ref in the request body is required by GitHub. You can specify your branch name here.

4. GraphCMS webhook

Login to GraphCMS and create a new webhook. Paste the Lambda endpoint into the Url field. GraphCMS allows you to choose Content Model, Stage and Action to control when our webhook is triggered.

(Of course you should care about security and also work with an Authorization Header here)

5. Test it!

Depending on which triggers you configured in the GraphCMS webhook settings (mostly publish and unpublish) you now can trigger a build and see your workflow running on GitHub.