treewide: more github runners + naive concurrency

modules/system/common/github-runner.nix

@@ -17,19 +17,28 @@
   };
 
   linuxConfig = lib.optionalAttrs isLinux {
-    services.github-runners =
-      lib.mapAttrs (name: cfg: {
-        enable = true;
-        tokenFile = config.age.secrets.github-token.path;
-        inherit (cfg) name url;
-        ephemeral = true;
-        user = github-runner-user;
-        serviceOverrides = {
-          DynamicUser = false;
-        };
-        extraLabels = ["nix"];
-      })
-      cfg.runners;
+    services.github-runners = lib.pipe cfg.runners [
+      (lib.mapAttrsToList (
+        name: cfg:
+          lib.genList (i:
+            lib.nameValuePair
+            "${name}-${toString i}"
+            {
+              enable = true;
+              tokenFile = config.age.secrets.github-token.path;
+              inherit (cfg) url;
+              name = "${cfg.name}-${toString i}";
+              user = github-runner-user;
+              serviceOverrides = {
+                DynamicUser = false;
+              };
+              extraLabels = ["nix"];
+            })
+          cfg.instances
+      ))
+      lib.flatten
+      lib.listToAttrs
+    ];
 
     users = {
       users.${github-runner-user} = {
@@ -59,6 +68,10 @@ in {
             url = mkOption {
               type = types.str;
             };
+            instances = mkOption {
+              type = types.int;
+              default = 1;
+            };
           };
         }));
     };