allow kos-mos to use ccache

Signed-off-by: Xe <me@christine.website>

hardware/alrest/jenkins-agent.nix

@@ -0,0 +1,79 @@
+{ config, lib, pkgs, ... }:
+with lib;
+let
+  cfg = config.within.services.jenkinsAgent;
+  masterCfg = config.services.jenkins;
+in {
+  options = {
+    within.services.jenkinsAgent = {
+      # todo:
+      # * assure the profile of the jenkins user has a JRE and any specified packages. This would
+      # enable ssh agents.
+      # * Optionally configure the node as a jenkins ad-hoc agent. This would imply configuration
+      # properties for the master node.
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          If true the system will be configured to work as a jenkins agent.
+          If the system is also configured to work as a jenkins master then this has no effect.
+          In progress: Currently only assures the jenkins user is configured.
+        '';
+      };
+
+      user = mkOption {
+        default = "jenkins-agent";
+        type = types.str;
+        description = ''
+          User the jenkins agent should execute under.
+        '';
+      };
+
+      group = mkOption {
+        default = "jenkins-agent";
+        type = types.str;
+        description = ''
+          If the default agent user "jenkins" is configured then this is
+          the primary group of that user.
+        '';
+      };
+
+      home = mkOption {
+        default = "/var/lib/jenkins-agent";
+        type = types.path;
+        description = ''
+          The path to use as JENKINS_HOME. If the default user "jenkins" is configured then
+          this is the home of the "jenkins" user.
+        '';
+      };
+
+      javaPackage = mkOption {
+        default = pkgs.jdk;
+        defaultText = literalExpression "pkgs.jdk";
+        description = ''
+          Java package to install.
+        '';
+        type = types.package;
+      };
+    };
+  };
+
+  config = mkIf (cfg.enable && !masterCfg.enable) {
+    users.groups = optionalAttrs (cfg.group == "jenkins-agent") {
+      jenkins-agent.gid = config.ids.gids.jenkins;
+    };
+
+    users.users.jenkins = {
+      description = "jenkins user";
+      createHome = true;
+      home = cfg.home;
+      group = cfg.group;
+      useDefaultShell = true;
+    };
+
+    programs.java = {
+      enable = true;
+      package = cfg.javaPackage;
+    };
+  };
+}

hosts/kos-mos/default.nix

@@ -7,6 +7,8 @@
   environment.systemPackages = with pkgs; [ nodejs-14_x ];
   services.tailscale.port = 15428;
 
+  nix.sandboxPaths = [ "/var/cache/ccache" ];
+
   networking.hostName = "kos-mos";
   networking.hostId = "472479d4";
 }