feat: initial docker image module

modules/default.nix

@@ -5,4 +5,5 @@
   istio = ./istio;
   testing = ./testing;
   helm = ./helm;
+  docker = ./docker;
 }

modules/docker/default.nix

@@ -0,0 +1,51 @@
+{ config, lib, ... }:
+
+with lib;
+
+{
+  options.docker.registry.url = mkOption {
+    description = "Default registry url where images are published";
+    type = types.str;
+  };
+
+  options.docker.images = mkOption {
+    description = "Attribute set of docker images that should be published";
+    type = types.attrsOf (types.submodule ({ name, config, ... }: {
+      options = {
+        image = mkOption {
+          description = "Docker image to publish";
+          type = types.nullOr types.package;
+          default = null;
+        };
+
+        name = mkOption {
+          description = "Desired docker image name";
+          type = types.str;
+          default = builtins.unsafeDiscardStringContext config.image.imageName;
+        };
+
+        tag = mkOption {
+          description = "Desired docker image tag";
+          type = types.str;
+          default = builtins.unsafeDiscardStringContext config.image.imageTag;
+        };
+
+        registry = mkOption {
+          description = "Docker registry url where image is published";
+          type = types.str;
+          default = config.docker.registry.url;
+        };
+      };
+    }));
+    default = {};
+  };
+
+  options.docker.push = mkOption {
+    description = "List of images to push";
+    type = types.listOf (types.package);
+    default = [];
+  };
+
+  config.docker.push = mapAttrsToList (_: i: i.image)
+    (filterAttrs (_: i: i.registry != null)config.docker.images);
+}