functions

Go Vanity Cloud Function

This is a simple Google Cloud Function written in Go that creates an HTTP request handler that handles Go Vanity import redirects.

The code is based off the GCP example repository.

Motivation

Vanity redirection is as simple as an HTTP redirect and I don't think deploying a server or even a container is necessary. This is one of the purest use cases for Cloud Functions.

Testing

A local testing framework is included. In order to test the redirection meta tags locally, set the LOCAL_PORT env value and localhost:$LOCAL_PORT will be used as the host value.

Now you can query http://localhost:$LOCAL_PORT.

Ex: Set DEBUG_ADDRESS=localhost:8080

curl -v http://localhost:8080 #index
curl -v http://localhost:8080/reponame #for a repo

Note: You still need to provide a valid remote configuration file which is read and the host value is overwritten by localhost:$LOCAL_PORT.

Deployment

To deploy this function, you need the following things

• A GCP Project (requires a GCP account).
• gcloud cli setup and configured locally.

After logging in, deploy the function using

$ gcloud functions deploy go-vanity-redirection --entry-point HandleImport --runtime go113 --trigger-http --memory 128MB --env-vars-file=./env.yml --allow-unauthenticated

Without the --allow-unauthenticated flag, the caller needs to provide some form of auth to call the URL. But since we want the vanity redirection to be public, we skip this.

Custom DNS

To use Custom DNS (ex: go.example.com), there needs to be a proxy/load-balancer in front of the cloud function.

The easiest and cheapest (free) option is to setup Firebase hosting.

• Go to the Firebase Console and setup a new free project (the Spark plan).
• Install the firebase CLI and login, the instructions of which can be found in the console.
• Create a dummy directory (ex: firebase) and initialize firebase.

$ cd <directory>
$ firebase init

• In the init options

  • Select "Hosting: Configure and deploy Firebase Hosting sites".
  • Either use your project that you selected above or create a new project.
  • Leave "What do you want to use as your public directory?" that default.
  • Select N for "Configure as a single-page app (rewrite all urls to /index.html)?".

• Remove the contents of the public folder (as we are not serving any static assets), but keep the empty folder.

• Replace the firebase.json with the following contents

{
  "hosting": {
    "public":"public",
    "redirects": [{
      "source": "/:project*",
      "destination": "https://<location-project-name>.cloudfunctions.net/<function-name>/:project",
      "type":301
    }
    ]
  }
}

The /:project* capture group catches the URI after / (which is the name of your project) and forwards it to your function.

You can checkin the above file and the firebase.rc file to a VCS to update and redeploy the project.

Once deployed, you check that the redirection works by going to the default Firebase App URL which is of the form firebase-project-xxxxx.web.app. xxxxx is a random 5 digit code assigned to your project by Firebase.

If this works correctly, then follow the Add Custom Domain guide in the Firebase Console to setup your custom domain.

Metrics

Runtime metrics for the cloud function are available in the GCP Console.

Similarly, Firebase hosting metrics are available in the Firebase Console.

License

The contents of this repository are released as is under the terms of the Apache 2.0 License.