nixos/nginx: add proxyCache options

nixos/modules/services/web-servers/nginx/default.nix

@@ -192,6 +192,14 @@ let
 
       server_tokens ${if cfg.serverTokens then "on" else "off"};
 
+      ${optionalString (cfg.proxyCache.enable) ''
+        proxy_cache_path /var/cache/nginx keys_zone=${cfg.proxyCache.keysZoneName}:${cfg.proxyCache.keysZoneSize}
+                                          levels=${cfg.proxyCache.levels}
+                                          use_temp_path=${if cfg.proxyCache.useTempPath then "on" else "off"}
+                                          inactive=${cfg.proxyCache.inactive}
+                                          max_size=${cfg.proxyCache.maxSize};
+      ''}
+
       ${cfg.commonHttpConfig}
 
       ${vhosts}
@@ -689,6 +697,72 @@ in
           '';
       };
 
+      proxyCache = mkOption {
+        type = types.submodule {
+          options = {
+            enable = mkEnableOption (lib.mdDoc "Enable proxy cache");
+
+            keysZoneName = mkOption {
+              type = types.str;
+              default = "cache";
+              example = "my_cache";
+              description = lib.mdDoc "Set name to shared memory zone.";
+            };
+
+            keysZoneSize = mkOption {
+              type = types.str;
+              default = "10m";
+              example = "32m";
+              description = lib.mdDoc "Set size to shared memory zone.";
+            };
+
+            levels = mkOption {
+              type = types.str;
+              default = "1:2";
+              example = "1:2:2";
+              description = lib.mdDoc ''
+                The levels parameter defines structure of subdirectories in cache: from
+                1 to 3, each level accepts values 1 or 2. Сan be used any combination of
+                1 and 2 in these formats: x, x:x and x:x:x.
+              '';
+            };
+
+            useTempPath = mkOption {
+              type = types.bool;
+              default = false;
+              example = true;
+              description = lib.mdDoc ''
+                Nginx first writes files that are destined for the cache to a temporary
+                storage area, and the use_temp_path=off directive instructs Nginx to
+                write them to the same directories where they will be cached. Recommended
+                that you set this parameter to off to avoid unnecessary copying of data
+                between file systems.
+              '';
+            };
+
+            inactive = mkOption {
+              type = types.str;
+              default = "10m";
+              example = "1d";
+              description = lib.mdDoc ''
+                Cached data that has not been accessed for the time specified by
+                the inactive parameter is removed from the cache, regardless of
+                its freshness.
+              '';
+            };
+
+            maxSize = mkOption {
+              type = types.str;
+              default = "1g";
+              example = "2048m";
+              description = lib.mdDoc "Set maximum cache size";
+            };
+          };
+        };
+        default = {};
+        description = lib.mdDoc "Configure proxy cache";
+      };
+
       resolver = mkOption {
         type = types.submodule {
           options = {