coder/docs/tutorials/reverse-proxy-caddy.md

Caddy

This is an example configuration of how to use Coder with caddy. To use Caddy to generate TLS certificates, you'll need a domain name that resolves to your Caddy server.

Getting started

With docker compose

1. Install Docker and Docker Compose

2. Create a compose.yaml file and add the following:

   services:
   coder:
       image: ghcr.io/coder/coder:${CODER_VERSION:-latest}
       environment:
           CODER_PG_CONNECTION_URL: "postgresql://${POSTGRES_USER:-username}:${POSTGRES_PASSWORD:-password}@database/${POSTGRES_DB:-coder}?sslmode=disable"
           CODER_HTTP_ADDRESS: "0.0.0.0:7080"
           # You'll need to set CODER_ACCESS_URL to an IP or domain
           # that workspaces can reach. This cannot be localhost
           # or 127.0.0.1 for non-Docker templates!
           CODER_ACCESS_URL: "${CODER_ACCESS_URL}"
           # Optional) Enable wildcard apps/dashboard port forwarding
           CODER_WILDCARD_ACCESS_URL: "${CODER_WILDCARD_ACCESS_URL}"
           # If the coder user does not have write permissions on
           # the docker socket, you can uncomment the following
           # lines and set the group ID to one that has write
           # permissions on the docker socket.
           #group_add:
           #  - "998" # docker group on host
       volumes:
           - /var/run/docker.sock:/var/run/docker.sock
       depends_on:
           database:
           condition: service_healthy
   
   database:
       image: "postgres:17"
       ports:
           - "5432:5432"
       environment:
           POSTGRES_USER: ${POSTGRES_USER:-username} # The PostgreSQL user (useful to connect to the database)
           POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-password} # The PostgreSQL password (useful to connect to the database)
           POSTGRES_DB: ${POSTGRES_DB:-coder} # The PostgreSQL default database (automatically created at first launch)
       volumes:
           - coder_data:/var/lib/postgresql/data # Use "docker volume rm coder_coder_data" to reset Coder
       healthcheck:
           test:
           [
               "CMD-SHELL",
               "pg_isready -U ${POSTGRES_USER:-username} -d ${POSTGRES_DB:-coder}",
           ]
           interval: 5s
           timeout: 5s
           retries: 5
   
   caddy:
       image: caddy:2.6.2
       ports:
           - "80:80"
           - "443:443"
           - "443:443/udp"
       volumes:
           - $PWD/Caddyfile:/etc/caddy/Caddyfile
           - caddy_data:/data
           - caddy_config:/config
   
   volumes:
       coder_data:
       caddy_data:
       caddy_config:
   

3. Create a Caddyfile and add the following:

   {
       on_demand_tls {
           ask http://example.com
       }
   }
   
   coder.example.com, *.coder.example.com {
     reverse_proxy coder:7080
     tls {
           on_demand
         issuer acme {
            email email@example.com
         }
         }
   }
   

   Here;

   • coder:7080 is the address of the Coder container on the Docker network.
   • coder.example.com is the domain name you're using for Coder.
   • *.coder.example.com is the domain name for wildcard apps, commonly used for dashboard port forwarding. This is optional and can be removed.
   • email@example.com: Email to request certificates from LetsEncrypt/ZeroSSL (does not have to be Coder admin email)

4. Start Coder. Set CODER_ACCESS_URL and CODER_WILDCARD_ACCESS_URL to the domain you're using in your Caddyfile.

   export CODER_ACCESS_URL=https://coder.example.com
   export CODER_WILDCARD_ACCESS_URL=*.coder.example.com
   docker compose up -d # Run on startup
   

Standalone

1. If you haven't already, install Coder

2. Install Caddy Server

3. Copy our sample Caddyfile and change the following values:

   {
       on_demand_tls {
           ask http://example.com
       }
   }
   
   coder.example.com, *.coder.example.com {
     reverse_proxy coder:7080
   }
   

   If you're installed Caddy as a system package, update the default Caddyfile with vim /etc/caddy/Caddyfile

   • email@example.com: Email to request certificates from LetsEncrypt/ZeroSSL (does not have to be Coder admin email)
   • coder.example.com: Domain name you're using for Coder.
   • *.coder.example.com: Domain name for wildcard apps, commonly used for dashboard port forwarding. This is optional and can be removed.
   • localhost:3000: Address Coder is running on. Modify this if you changed CODER_HTTP_ADDRESS in the Coder configuration.
   • DO NOT CHANGE the ask http://example.com line! Doing so will result in your certs potentially not being generated.

4. Configure Coder and change the following values:

   • CODER_ACCESS_URL: root domain (e.g. https://coder.example.com)
   • CODER_WILDCARD_ACCESS_URL: wildcard domain (e.g. *.example.com).

5. Start the Caddy server:

   If you're keeping Caddy running via a system service:

   sudo systemctl restart caddy
   

   Or run a standalone server:

   caddy run
   

6. Optionally, use ufw or another firewall to disable external traffic outside of Caddy.

   # Check status of UncomplicatedFirewall
   sudo ufw status
   
   # Allow SSH
   sudo ufw allow 22
   
   # Allow HTTP, HTTPS (Caddy)
   sudo ufw allow 80
   sudo ufw allow 443
   
   # Deny direct access to Coder server
   sudo ufw deny 3000
   
   # Enable UncomplicatedFirewall
   sudo ufw enable
   

7. Navigate to your Coder URL! A TLS certificate should be auto-generated on your first visit.

Generating wildcard certificates

By default, this configuration uses Caddy's on-demand TLS to generate a certificate for each subdomain (e.g. app1.coder.example.com, app2.coder.example.com). When users visit new subdomains, such as accessing ports on a workspace, the request will take an additional 5-30 seconds since a new certificate is being generated.

For production deployments, we recommend configuring Caddy to generate a wildcard certificate, which requires an explicit DNS challenge and additional Caddy modules.

1. Install a custom Caddy build that includes the caddy-dns module for your DNS provider (e.g. CloudFlare, Route53).

   • Docker: Build an custom Caddy image with the module for your DNS provider. Be sure to reference the new image in the compose.yaml.

   • Standalone: Download a custom Caddy build with the module for your DNS provider. If you're using Debian/Ubuntu, you can configure the Caddy package to use the new build.

2. Edit your Caddyfile and add the necessary credentials/API tokens to solve the DNS challenge for wildcard certificates.

   For example, for AWS Route53:

   tls {
   -  on_demand
   -  issuer acme {
   -      email email@example.com
   -  }
   
   +  dns route53 {
   +     max_retries 10
   +     aws_profile "real-profile"
   +     access_key_id "AKI..."
   +     secret_access_key "wJa..."
   +     token "TOKEN..."
   +     region "us-east-1"
   +  }
   }
   

   Configuration reference from caddy-dns/route53.

   And for CloudFlare:

   Generate a token with the following permissions:

   • Zone:Zone:Edit

   tls {
   -  on_demand
   -  issuer acme {
   -      email email@example.com
   -  }
   
   +  dns cloudflare CLOUDFLARE_API_TOKEN
   }
   

   Configuration reference from caddy-dns/cloudflare.