Caddy NixOS container setup

Apr 17, 2023 - 4 min read

Introduction

Caddy is a simple, open-source web server that I use as a local reverse proxy.

Setup

NixOS Configuration

Note

This configuration uses Podman as container backend.

1. Add virtualisation to configuration.nix

   Add virtualisation and the import to a seperate nix file for the container to configuration.nix:

   Linux

   /etc/nixos/configuration.nix

     # To edit use your text editor application, for example Nano
     virtualisation = {
       podman = {
         enable = true;
         dockerCompat = true; # Create a `docker` alias for podman, to use it as a drop-in replacement
         defaultNetwork.settings.dns_enabled = true; # release 23.05
       };
       oci-containers = {
         backend = "podman";
         containers = {
           caddy = import ./containers/caddy.nix;
         };
       };
     };

2. Add the macvlan network to configuration.nix

   The container will use a macvlan network (net_macvlan) with a dedicated IP address. Add the following to configuration.nix:

   Linux

   /etc/nixos/configuration.nix

   # To edit use your text editor application, for example Nano
   systemd.services.create-podman-network = with config.virtualisation.oci-containers; {
     serviceConfig.Type = "oneshot";
     wantedBy = [ "${backend}-caddy.service" ];
     script = ''${pkgs.podman}/bin/podman network exists net_macvlan || \ ${pkgs.podman}/bin/podman network create --driver=macvlan --gateway=192.168.1.1 --subnet=192.168.1.0/24 -o parent=ens18 net_macvlan'';
   };
   # IMPORTANT: Please read the instructions below

   Instructions:

   • Required Replace 192.168.1.1 with your gateway IP address
   • Required Replace 192.168.1.0 with your subnet
   • Required Replace ens18 with the name of own network interface

3. Add a script to create folders to configuration.nix

   Make sure the folders for use with the container are created by adding the following to configuration.nix:

   Linux

   /etc/nixos/configuration.nix

   # To edit use your text editor application, for example Nano
   system.activationScripts = {
     script.text = ''
       install -d -m 755 /home/<username>/caddy/site -o root -g root
       install -d -m 755 /home/<username>/caddy/data -o root -g root
       install -d -m 755 /home/<username>/caddy/config -o root -g root
       test -f /home/<username>/caddy/Caddyfile || echo -e "#{\n#       debug\n#}" > /home/<username>/caddy/Caddyfile
       '';
   };
   # IMPORTANT: Please read the instructions below

   Caution

   Make sure the folders are created with the root user and group, else the container will not work properly

   Instructions:

   • Required Replace <username> with your NixOS username

4. Create the containers folder

   Run the following command:

   Linux

   # Open your terminal application
   mkdir -p /etc/nixos/containers # Make sure the directory exists

5. Add the container configuration to caddy.nix

   Add the following to caddy.nix:

   Linux

   /etc/nixos/containers/caddy.nix

   # To edit use your text editor application, for example Nano
   {
     image = "caddy:latest";
   
     environment = {
       "TZ" = "Europe/Amsterdam";
     };
   
     volumes = [
       "/home/<username>/caddy/Caddyfile:/etc/caddy/Caddyfile"
       "/home/<username>/caddy/site:/usr/share/caddy"
       "/home/<username>/caddy/data:/data"
       "/home/<username>/caddy/config:/config"
     ];
   
     extraOptions = [
       "--pull=newer" # Pull if the image on the registry is newer than the one in the local containers storage
       "--name=caddy"
       "--hostname=caddy"
       "--network=net_macvlan"
       "--ip=<IP address>"
       "--mac-address=<MAC address>"
     ];
   }
   # IMPORTANT: Please read the instructions below

   Instructions:

   • Required Replace Europe/Amsterdam with your own timezone
   • Required Replace <username> with your NixOS username
   • Optional Replace --pull=newer with --pull=never if you do not want the image to be automatically replaced by new versions
   • Optional Replace net_macvlan with the name of your macvlan network if needed
   • Required Replace <IP address> with the IP address of this container. Make sure it is within the range of the macvlan network
   • Required Replace <MAC address> a (randomly generated) MAC address. Otherwise, every time the container is started, a new mac address will be used, which for example will be created as a new device within the Unifi Network Application. Or temporarily disable this option, and add the MAC address that is generated the first time when this container is started. Use inspect to get the MAC address if needed: sudo podman inspect <container name> |grep MacAddress|tr -d ' ,"'|sort -u

6. Switch NixOS configuration

   Now you can switch to the new configuration within NixOS, the image will be downloaded and the container will be created:

   Run the following command:

   Linux

   # Open your terminal application
   sudo nix-collect-garbage # Optional: clean up
   sudo nixos-rebuild switch

7. Check the results

   Run the following command to check if the container is working properly:

   Linux

   # Open your terminal application
   journalctl -u podman-caddy.service

   Tip

   You can find the Caddyfile at /home/<NixOS username>/caddy/Caddyfile and set up a reverse proxy from there.

Favorites

Caddy docs

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Tags:

• Virtualisation
• Linux

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