How to add health check endpoint for global load balancing

[aviita]

We have created an app with node template using:
```
npm init @Shopify/app@latest
```

It seems to have been made exceptionally hard to modify the routes of this template application to have a simple health check endpoint like `/healthz`, which responds with HTTP 200. This is usually a requirement with load balancing services like Azure Front Door to distribute our app globally.

Could you provide an easy way to do this or even include it into your templates?

I would imagine this to be especially necessary when using Shopify App Bridge, where the app can handle calls by the store front.

[Vellir · Accepted solution]

Hi Aviita,

It should be as simple as adding this to server/index.js:

  app.get('/healthz', (req, res) => {
    res.status(200).send();
  });

Have a look at the expressJS documentation for more examples of how to create routes.

[aviita]

Could have put in more details. Been trying this and it gets hijacked by other middleware:

  app.use("/api/healthz", (req, res, next) => {
    console.log(`Health check endpoint called`);
    res.status(200).send({ success: true });
  });

And same with that `/healthz`, and this is with plain App I just created to ensure our app that has seen some development (different message though than with `/api/healthz`.

Placed it just above the `/*`:

  app.use("/healthz", (req, res, next) => {
    console.log(`Health check endpoint called`);
    res.status(200).send({ success: true });
  });

  app.use("/*", async (req, res, next) => {

[aviita]

Ha, it actually does work when deployed to server. Just some problem with my localhost setup. Thanks for inserting some more hope in me. 🙂

[aviita]

And additionally see that I slipped into registering my endpoint as middleware instead of get endpoint, but  that was my attempt to ensure it would get precedence over other middleware.

But I verified now that on server both solutions work.