DecapCMS Lambda Oauth2 Backend

DecapCMS is an open source project that you can use without using Netlify. In order to do so, you need a way to authenticate; one of the ways to do this is using GitHub oAuth. If you're going to do that though, you need a server-side component acting as the oAuth client, allowing your admin users to connect to GitHub's servers to authenticate.

This application "DecapCMS Lambda Oauth2 Backend" acts as a lightweight OAuth Provider wrapper that works on AWS Lambda and Amazon API Gateway instead of the Netlify Auth API.

Feature

• GitHub OAuth Provider
• [] GitLab OAuth Provider

Deploy

1. OAuth Provider setup

You need to create an API application and make note of the Client ID and a Client Secret so that you can use them in your configuration.

1. In GitHub, go to your account Settings and select Developer Settings, then OAuth Apps or use this shortcut.

2. Select Register a new application.

3. For the Authorization callback URL, enter https://xxxx.execute-api.ap-northeast-1.amazonaws.com/prod/callback. *Set this value again after you deploy API Gateway.

2. Deploy API Gateway and AWS Lambda

To save GitHub's OAuth Client ID and Secret in Lambda's environment variables, save the values in Parameter Store in advance.

$ aws ssm put parameter \
    --type 'String' \
    --name '/CDK/DecapCMSOAuthBackend/OAUTH_GITHUB_CLIENT_ID' \
    --value 'df2655731exxxxxxxx'

$ aws ssm put-parameter \
    --type 'String' \
    --name '/CDK/DecapCMSOAuthBackend/OAUTH_GITHUB_CLIENT_SECRET' \
    --value '26badbd6ecxxxxxxxxxxxxxxxxxxxxxx'

then

$ cdk deploy

Make a note of the API Gateway endpoint that is output to the console. Set this endpoint in the Authorization callback URL on the GitHub Developer Settings page.

3. CMS Config

You also need to add base_url to the backend section of your DecapCMS's config file. base_url is the live URL of this repo with no trailing slashes.

backend:
  name: github
  repo: user/repo # Path to your GitHub repository
  branch: main
  base_url: https://xxxx.execute-api.ap-northeast-1.amazonaws.com # your apigateway endpoint
  auth_endpoint: /prod/auth