Merge pull request #196417 from jfroche/feat/cachix-watch-store

nixos: add cachix watch-store service

nixos/modules/services/system/cachix-watch-store.nix

@@ -0,0 +1,87 @@
+{ config, pkgs, lib, ... }:
+
+with lib;
+
+let
+  cfg = config.services.cachix-watch-store;
+in
+{
+  meta.maintainers = [ lib.maintainers.jfroche lib.maintainers.domenkozar ];
+
+  options.services.cachix-watch-store = {
+    enable = mkEnableOption (lib.mdDoc "Cachix Watch Store: https://docs.cachix.org");
+
+    cacheName = mkOption {
+      type = types.str;
+      description = lib.mdDoc "Cachix binary cache name";
+    };
+
+    cachixTokenFile = mkOption {
+      type = types.path;
+      description = lib.mdDoc ''
+        Required file that needs to contain the cachix auth token.
+      '';
+    };
+
+    compressionLevel = mkOption {
+      type = types.nullOr types.int;
+      description = lib.mdDoc "The compression level for XZ compression (between 0 and 9)";
+      default = null;
+    };
+
+    jobs = mkOption {
+      type = types.nullOr types.int;
+      description = lib.mdDoc "Number of threads used for pushing store paths";
+      default = null;
+    };
+
+    host = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = lib.mdDoc "Cachix host to connect to";
+    };
+
+    verbose = mkOption {
+      type = types.bool;
+      description = lib.mdDoc "Enable verbose output";
+      default = false;
+    };
+
+    package = mkOption {
+      type = types.package;
+      default = pkgs.cachix;
+      defaultText = literalExpression "pkgs.cachix";
+      description = lib.mdDoc "Cachix Client package to use.";
+    };
+
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.cachix-watch-store-agent = {
+      description = "Cachix watch store Agent";
+      after = [ "network-online.target" ];
+      path = [ config.nix.package ];
+      wantedBy = [ "multi-user.target" ];
+      serviceConfig = {
+        # we don't want to kill children processes as those are deployments
+        KillMode = "process";
+        Restart = "on-failure";
+        DynamicUser = true;
+        LoadCredential = [
+          "cachix-token:${toString cfg.cachixTokenFile}"
+        ];
+      };
+      script =
+        let
+          command = [ "${cfg.package}/bin/cachix" ]
+            ++ (lib.optional cfg.verbose "--verbose") ++ (lib.optionals (cfg.host != null) [ "--host" cfg.host ])
+            ++ [ "watch-store" ] ++ (lib.optionals (cfg.compressionLevel != null) [ "--compression-level" (toString cfg.compressionLevel) ])
+            ++ (lib.optionals (cfg.jobs != null) [ "--jobs" (toString cfg.jobs) ]) ++ [ cfg.cacheName ];
+        in
+        ''
+          export CACHIX_AUTH_TOKEN="$(<"$CREDENTIALS_DIRECTORY/cachix-token")"
+          ${lib.escapeShellArgs command}
+        '';
+    };
+  };
+}