Setup a Scalable Ghost With Docker and Traefik

2018/06/08

I was hosting my static web site on Netlify. Then Github announced support for HTTPS on custom domains and I migrated there. Recently I bought an iPad Pro. Since I hold my SSH keys on my Yubikeys there is no easy way to write a post on my iPad and push it to Github. So I decided give Ghost a try.

The biggest advantage of having Netlify or Github host your website, you don’t have to worry about your sites availability. It’s somebody else’s problem. But I like things to be responsible of. I wanted it to be my problem. I decided to deploy Ghost on a Centos virtual machine.

I used docker images for Ghost. By default it uses a SQLite database. It means I can’t scale my blog without sharing SQLite database between containers. I decided to go with an external MySQL container.

Initially I have Nginx in my mind to use as reverse proxy. But while researching about it I came across to one of the most beautiful piece of software I’ve encountered: Traefik. It was a pure joy to configure and run it, because I didn’t configure anything. I just give docker’s socket path to Traefik and it just worked.

Traefik handles routing by container labels. For example to docker-compose.yml file of Ghost I added this:

labels:
    - "traefik.frontend.rule=Host:gunes.io"

Traefik listens 80 and if Host header in request is “gunes.io”, it routes this request to Ghost. If I scale Ghost to 2 containers or more, it automatically load balance between them. You don’t need anything other than default configuration for it.

But I need more of course. First I wanted to fetch metrics with Prometheus. So I enabled the config option. Second I wanted to have SSL. So I tried to configure Traefik automatically issue Let’s Encrypt certificate by my frontend rules. It didn’t work and I hit the rate limit for my IP.

Honeymoon must end sometime.