Run docker-compose on GCE

I created this experiment because I wanted a way to run a managed docker-compose stack.

There are many services that will run a docker container for you and many services that will manage a k8s deployment for you, but sometimes one docker container is not enough and k8s is just way too much for a hobby project or internal tool.

This projects uses a GCE VM instance to host a docker-compose stack.

GCE allows you to deploy a container that it will always keep running.

⚠️ This project uses traefik for a reverse proxy to expose multiple services on the same port. The examples I use can be run as is for a proof of concept, but to customize the examples for your own project you will need an understanding of how traefik works and it is not discussed in detail here.

The Idea

Extend the docker/compose image by adding my own docker-compose.yml to it. I can then use that to run multiple docker containers masquerading as one docker container.

You can then run it with something like:

docker build -t example .
docker run --rm -ti \
  -v /var/run/docker.sock:/var/run/docker.sock \
  example up

Basic compose file

docker-compose.yml runs three http services.

It uses traefik to route you to each service based on the path you navigate to.

To test it locally run:

docker-compose up

Any URL starting with http://localhost/server1 will route you to server1.
Any URL starting with http://localhost/server2 will route you to server2.
Any other URL will route you to the default server.

Compose file with https, SNI and Let's Encrypt certificates

docker-compose.advanced.yml runs three https services.

It uses traefik to route you to each service based on hostname.

It uses Let's Encrypt to generate certificates for all three services.

You set the default server's hostname with the environment variable BASE_URL.

Any URL starting with https://server1.${BASE_URL} will route you to server1.
Any URL starting with https://server2.${BASE_URL} will route you to server2.
Any URL starting with https://${BASE_URL} route you to the default server.

To test it locally run:

docker-compose -f docker-compose.advanced.yml up

By default the BASE_URL will be localhost and you will not be able to get Let's Encrypt certificates, but you can still test it.

GCE Setup

This is GCE setup instructions for using the image from my basic Dockerfile.

You will need to log in to GCP and create a project with billing enabled.

Then go to Compute Engine -> VM Instances and create an instance.

Choose the name, region, zone, machine type etc. that you prefer (or use the defaults).

Tick Deploy a container image to this VM instance.

At Container image enter ghcr.io/jedrivisser/gce-compose:1.0.0.

Click Advanced container options to see more options.

Under Command arguments click Add argument and enter up.

Under Volume mounts select Add volume and add a volume mount with:

Name	Value
Volume type	Directory
Mount path	/var/run/docker.sock
Host path	/var/run/docker.sock
Mode	Read-only

At firewall select Allow HTTP traffic.

Then click Create and wait a few minutes for it to start up.

That's it! You can now access your services on the external IP GCE assigned to you.

In my case http://35.208.21.157/, http://35.208.21.157/server1 and http://35.208.21.157/server2.

GCE Setup Advanced

⚠️ You will need to own a domain or have access to add DNS entries to one.

This is GCE setup instructions for using the image from my advanced.Dockerfile.

You will need to log in to GCP and create a project with billing enabled.

Then go to Compute Engine -> VM Instances and create an instance.

You will probably want a static external IP for this https setup so first go to the bottom of the instance setup page.

Click Management, security, disks, networking, sole tenancy to see more options.

Select the Networking tab and under External IP select Create IP address.

Give it some name and description that makes sense and select Reserve.

In my case I now have the IP 35.209.113.152.

Add 3 DNS entries that reference this IP, ${BASE_URL}, server1.${BASE_URL} and server2.${BASE_URL}. My DNS is managed by Cloudflare so I added it there.

Now lets go back to the top of the page and configure the VM.

Choose the name, region, zone, machine type etc. that you prefer (or use the defaults).

Tick Deploy a container image to this VM instance.

At Container image enter ghcr.io/jedrivisser/gce-compose/advanced:1.0.0.

Click Advanced container options to see more options.

Under Command arguments click Add argument and enter up.

Under Environment variables click Add variable and add your BASE_URL for this service, in my case:

Name	Value
BASE_URL	gcecompose.jedrivisser.com

Under Volume mounts select Add volume and add a volume mount with:

Name	Value
Volume type	Directory
Mount path	/var/run/docker.sock
Host path	/var/run/docker.sock
Mode	Read-only

At firewall select Allow HTTP traffic and Allow HTTPS traffic.

Then click Create and wait a few minutes for it to start up.

That's it! You can now access your services on the specified hostname.

In my case https://gcecompose.jedrivisser.com, https://server1.gcecompose.jedrivisser.com and https://server2.gcecompose.jedrivisser.com.

Limitations

There are probably more restrictions that I will add if I think of them / encounter them, but for now:

• The docker-compose file cannot use volume mounts for this use case.
• Only port 80 and 443 can be exposed.