Allow multiple apps to be deployed to the same server

[jaydrogers]

👉 Describe the problem

Spin only supports one app stack to be deployed to a server.

👥 Problem evidence & reach

• https://discord.com/channels/910287105714954251/910299290230997003/1316075190026895452

🥰 Describe the "impact" on users?

This could save some users money and complexity so they don't need to manage multiple servers.

🏆 How to solve this problem

Create a "Spin Proxy" variable

This could be something enabled in the .spin.yml where users could enable "multitenancy". This would have the Ansible playbook create a default proxy (like Traefik). Once that "global service" is running, then users can use external networks to join to the proxy: https://docs.docker.com/compose/how-tos/networking/#use-a-pre-existing-network

💯 How do we validate the problem is solved?

• A user can deploy multiple apps to the same server

[luchfirearmland]

Been waiting for this!!!! 🎉 (And InertiaJS SSR as well 🤣)

[vesper8]

Been waiting for this for 6 months too! Still waiting!

[jaydrogers]

My goal today was to get a better post put together, but I had a discussion with @harrisonratcliffe today and figured I would share these very quick notes. There is a chance as some of you chime in, I will put this into a better form of documentation and/or video.

Background & TL;DR

I plan to automate and simplify this process natively in Spin, but it will take time to do this correctly. Instead of waiting I wanted to share notes that it is possible to run multiple apps on a single server with Docker Swarm (what Spin uses) today.

If you feel like tinkering, follow this quick guide.

Important concepts

1. When run a deployment with Spin on a server, it creates a Docker network with Traefik by default
2. Traefik can proxy requests to multiple apps using labels: differentiate where to send traffic
3. We can deploy a 2nd app to the same server, as long as we join it to an existing network that has Traefik running on it

More about the concept is here: https://docs.docker.com/compose/how-tos/networking/#use-an-existing-network

Deploy and app with Spin

Run a usual deployment. It will have Traefik.

Create a 2nd app

You can create another app. It will have Traefik in the docker-compose.prod.yml file. What you want to do is delete any reference of Traefik in that config. We want to use the Traefik instance from the original app.

Important

If you try to deploy Traefik to the same server, it will fail because another service is already using HTTP (80) and HTTPS (443)

Adjust networks on the new app

You'll see in the docker-compose.prod.yml file has it's network definition:

services:
  php:
    image: ${SPIN_IMAGE_DOCKERFILE_PHP}
    networks:
      - web-public

We don't want to use web-public.

Instead, SSH into your server and run sudo docker network ls. You might have a network called spin_web-public (or something like that). That's the "external network" we want to use.

So in our 2nd app, we want to change that network to EXACTLY MATCH and ALSO DECLARE that spin_web-public is an external network:

services:
  php:
    image: ${SPIN_IMAGE_DOCKERFILE_PHP}
    networks:
      - spin_web-public
networks:
  spin_web-public:
    external: true

Important

Make sure you update both the network: key and add the networks: key as I have above.

Change the docker labels for Traefik

The next part is to get the Traefik configurations set, which is all done through labels:.

The original labels look like this:

      labels:
        - "traefik.enable=true"
        - "traefik.http.routers.laravel-web.rule=Host(`${SPIN_APP_DOMAIN}`)"
        - "traefik.http.routers.laravel-web.entrypoints=websecure"
        - "traefik.http.routers.laravel-web.tls=true"
        - "traefik.http.routers.laravel-web.tls.certresolver=letsencryptresolver"
        - "traefik.http.services.laravel-web.loadbalancer.server.port=8443"
        - "traefik.http.services.laravel-web.loadbalancer.server.scheme=https"
        # Health check
        - "traefik.http.services.laravel-web.loadbalancer.healthcheck.path=/up"
        - "traefik.http.services.laravel-web.loadbalancer.healthcheck.interval=30s"
        - "traefik.http.services.laravel-web.loadbalancer.healthcheck.timeout=5s"
        - "traefik.http.services.laravel-web.loadbalancer.healthcheck.scheme=https"

Notice a few key things here:

• traefik.http.routers.laravel-web.rule sets the domain, which is set by ${SPIN_APP_DOMAIN}. You can try using SPIN_APP_DOMAIN, just make sure that variable is being set correctly (example.com).
• The Traefik labels need to be unique on a per app basis (laravel-web from above). If you deploy another app with the same labels, you'll have problems.

This means on your second app, you need to rename laravel-web to laravel-web2 (or at least something different).

Again, make sure you're setting SPIN_APP_DOMAIN correctly in the process.

Run a deployment

Deploy that sh*t and hopefully it will work 🤠