Easier alternative to Nginx + Lets Encrypt with Caddy Docker Proxy

So this is a request I get probably 4-5 times a year. "I'm looking to host a small application in docker and I need it to be easy to run through a GitLab/GitHub CICD pipeline, it needs SSL and I never ever want to think about how it works." Up until this point in my career the solution has been pretty consistent: Nginx with Let's Encrypt. Now you might think "oh, this must be a super common request and very easy to do." You would think that.

However the solution I've used up to this point has been frankly pretty shitty. It usually involves a few files that look like this:

services:
    web: 
        image: nginx:latest
        restart: always
        volumes:
            - ./public:/var/www/html
            - ./conf.d:/etc/nginx/conf.d
            - ./certbot/conf:/etc/nginx/ssl
            - ./certbot/data:/var/www/certbot
        ports:
            - 80:80
            - 443:443

    certbot:
        image: certbot/certbot:latest
        command: certonly --webroot --webroot-path=/var/www/certbot --email [email protected] --agree-tos --no-eff-email -d domain.com -d www.domain.com
        volumes:
            - ./certbot/conf:/etc/letsencrypt
            - ./certbot/logs:/var/log/letsencrypt
            - ./certbot/data:/var/www/certbot

This sets up my webserver with Nginx bound to host ports 80 and 443 along with the certbot image. Then I need to add the Nginx configuration to handle forwarding traffic to the actual application which is defined later in the docker-compose file along with everything else I need. It works but its a hassle. There's a good walkthrough of how to set this up if you are interested here: https://pentacent.medium.com/nginx-and-lets-encrypt-with-docker-in-less-than-5-minutes-b4b8a60d3a71

This obviously works but I'd love something less terrible. Enter Caddy Docker Proxy: https://github.com/lucaslorentz/caddy-docker-proxy. Here is an example of Grafana running behind SSL:

services:
  caddy:
    image: lucaslorentz/caddy-docker-proxy:ci-alpine
    ports:
      - 80:80
      - 443:443
    environment:
      - CADDY_INGRESS_NETWORKS=caddy
    networks:
      - caddy
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - caddy_data:/data
    restart: unless-stopped
    
  grafana:
    environment:
      GF_SERVER_ROOT_URL: "https://GRAFANA_EXTERNAL_HOST"
      GF_INSTALL_PLUGINS: "digiapulssi-breadcrumb-panel,grafana-polystat-panel,yesoreyeram-boomtable-panel,natel-discrete-panel"
    image: grafana/grafana:latest-ubuntu
    restart: unless-stopped
    volumes:
      - grafana-storage:/var/lib/grafana
      - ./grafana/grafana.ini:/etc/grafana/grafana.ini
    networks:
      - caddy
    labels:
      caddy: grafana.example.com
      caddy.reverse_proxy: "{{upstreams 3000}}"

  prometheus:
    image: prom/prometheus:latest
    volumes:
      - prometheus-data:/prometheus
      - ./prometheus/config:/etc/prometheus
    ports:
      - 9090:9090
    restart: unless-stopped
    networks:
      - caddy

How it works is super simple. Caddy listens on the external ports and proxies traffic to your docker applications. In return, your docker applications tell Caddy Proxy what url they need. It goes out, generates the SSL certificate for grafana.example.com as specified above and stores it in its volume. That's it, otherwise you are good to go.

Let's use the example from this blog as a good test case. If you want to set up a site that is identical to this one, here is a great template docker compose for you to run.

services:

  ghost:
    image: ghost:latest
    restart: always
    networks:
      - caddy
    environment:
      url: https://matduggan.com
    volumes:
      - /opt/ghost_content:/var/lib/ghost/content
    labels:
      caddy: matduggan.com
      caddy.reverse_proxy: "{{upstreams 2368}}"

  caddy:
    image: lucaslorentz/caddy-docker-proxy:ci-alpine
    ports:
      - 80:80
      - 443:443
    environment:
      - CADDY_INGRESS_NETWORKS=caddy
    networks:
      - caddy
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - caddy_data:/data
    restart: unless-stopped

networks:
  caddy:
    external: true

volumes:
  caddy_data: {}

So all you need to do in order to make a copy of this site in docker-compose is:

  1. Install Docker Compose.
  2. Run docker network create caddy
  3. Replace matduggan.com with your domain name
  4. Run docker-compose up -d
  5. Go to your domain and set up your Ghost credentials.

It really couldn't be more easy and it works like that for a ton of things like Wordpress, Magento, etc. It is, in many ways, idiot proof AND super easy to automate with a CICD pipeline using a free tier.

I've dumped all the older Let's Encrypt + Nginx configs for this one and couldn't be happier. Performance has been amazing, Caddy as a tool is extremely stable and I have not had to think about SSL certificates since I started. Strongly recommend for small developers looking to just get something on the internet without thinking about it or even larger shops where you have an application that doesn't justify going behind a load balancer.

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