thanatos: add Nix runner

hosts/thanatos/default.nix

@@ -40,9 +40,49 @@ in {
       settings = {
         concurrent = 4;
       };
-      services.default = {
+      services = {
-        authenticationTokenConfigFile = config.age.secrets."gitlab-runner/thanatos-runner-env".path;
+        nix = {
-        dockerImage = "debian:stable";
+          authenticationTokenConfigFile = config.age.secrets."gitlab-runner/thanatos-nix-runner-env".path;
+          dockerImage = "alpine";
+          dockerVolumes = [
+            "/nix/store:/nix/store:ro"
+            "/nix/var/nix/db:/nix/var/nix/db:ro"
+            "/nix/var/nix/daemon-socket:/nix/var/nix/daemon-socket:ro"
+          ];
+          dockerDisableCache = true;
+          preBuildScript = pkgs.writeScript "setup-container" ''
+            mkdir -p -m 0755 /nix/var/log/nix/drvs
+            mkdir -p -m 0755 /nix/var/nix/gcroots
+            mkdir -p -m 0755 /nix/var/nix/profiles
+            mkdir -p -m 0755 /nix/var/nix/temproots
+            mkdir -p -m 0755 /nix/var/nix/userpool
+            mkdir -p -m 1777 /nix/var/nix/gcroots/per-user
+            mkdir -p -m 1777 /nix/var/nix/profiles/per-user
+            mkdir -p -m 0755 /nix/var/nix/profiles/per-user/root
+            mkdir -p -m 0700 "$HOME/.nix-defexpr"
+
+            . ${pkgs.nix}/etc/profile.d/nix.sh
+
+            ${pkgs.nix}/bin/nix-env -i ${lib.concatStringsSep " " (with pkgs; [nix cacert git openssh])}
+
+            ${pkgs.nix}/bin/nix-channel --add https://nixos.org/channels/nixpkgs-unstable
+            ${pkgs.nix}/bin/nix-channel --update nixpkgs
+
+            mkdir -p ~/.config/nix
+            echo "experimental-features = nix-command flakes" > ~/.config/nix/nix.conf
+          '';
+          environmentVariables = {
+            ENV = "/etc/profile";
+            USER = "root";
+            NIX_REMOTE = "daemon";
+            PATH = "/nix/var/nix/profiles/default/bin:/nix/var/nix/profiles/default/sbin:/bin:/sbin:/usr/bin:/usr/sbin";
+            NIX_SSL_CERT_FILE = "/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt";
+          };
+        };
+        default = {
+          authenticationTokenConfigFile = config.age.secrets."gitlab-runner/thanatos-runner-env".path;
+          dockerImage = "debian:stable";
+        };
       };
     };
     openssh.enable = true;

hosts/thanatos/secrets.nix

@@ -16,6 +16,7 @@
         "users/alarsyo-hashed-password" = {};
         "users/root-hashed-password" = {};
         "gitlab-runner/thanatos-runner-env" = {};
+        "gitlab-runner/thanatos-nix-runner-env" = {};
       };
   };
 }

modules/secrets/secrets.nix

@@ -14,6 +14,7 @@ in {
   "gandi/api-key.age".publicKeys = [alarsyo hades];
 
   "gitlab-runner/thanatos-runner-env.age".publicKeys = [alarsyo thanatos];
+  "gitlab-runner/thanatos-nix-runner-env.age".publicKeys = [alarsyo thanatos];
 
   "lohr/shared-secret.age".publicKeys = [alarsyo hades];