From 7afbc91301e5081bc5854fde7e9d97ac30b5ec56 Mon Sep 17 00:00:00 2001
From: Jaka Hudoklin <jaka@x-truder.net>
Date: Sun, 6 Oct 2019 21:30:20 +0200
Subject: [PATCH] feat: make propagation independent of submodules

---
 modules/base.nix       | 36 ++++++++++++++++++++------
 modules/docker.nix     |  9 +++++--
 modules/k8s.nix        | 57 +++++++++++++++++++++++++-----------------
 modules/submodules.nix | 19 +++++++++-----
 4 files changed, 82 insertions(+), 39 deletions(-)

diff --git a/modules/base.nix b/modules/base.nix
index 22ee137..8e8517c 100644
--- a/modules/base.nix
+++ b/modules/base.nix
@@ -3,17 +3,37 @@
 with lib;
 
 {
-  options._module.features = mkOption {
-    description = "List of features exposed by module";
-    type = types.listOf types.str;
-    default = [];
-  };
-
-  options.kubenix = {
-    project = mkOption {
+  options = {
+    kubenix.project = mkOption {
       description = "Name of the project";
       type = types.str;
       default = "kubenix";
     };
+
+    _module.features = mkOption {
+      description = "List of features exposed by module";
+      type = types.listOf types.str;
+      default = [];
+    };
+
+    _module.propagate = mkOption {
+      description = "Module propagation options";
+      type = types.listOf (types.submodule ({config, ...}: {
+        options = {
+          features = mkOption {
+            description = "List of features that submodule has to have to propagate module";
+            type = types.listOf types.str;
+            default = [];
+          };
+
+          module = mkOption {
+            description = "Module to propagate";
+            type = types.unspecified;
+            default = {};
+          };
+        };
+      }));
+      default = [];
+    };
   };
 }
diff --git a/modules/docker.nix b/modules/docker.nix
index b9f3264..6b9f6d6 100644
--- a/modules/docker.nix
+++ b/modules/docker.nix
@@ -5,6 +5,8 @@ with lib;
 let
   cfg = config.docker;
 in {
+  imports = [ ./base.nix ];
+
   options.docker = {
     registry.url = mkOption {
       description = "Default registry url where images are published";
@@ -70,13 +72,16 @@ in {
   };
 
   config = {
+    # define docker feature
     _module.features = ["docker"];
 
+    # pass docker library as param
     _module.args.docker = import ../lib/docker.nix { inherit lib pkgs; };
 
-    submodules.defaults = [{
+    # propagate docker options if docker feature is enabled
+    _module.propagate = [{
       features = [ "docker" ];
-      default = { config, name, ... }: {
+      module = { config, name, ... }: {
         # propagate registry options
         docker.registry = cfg.registry;
       };
diff --git a/modules/k8s.nix b/modules/k8s.nix
index 07b02e5..a72585c 100644
--- a/modules/k8s.nix
+++ b/modules/k8s.nix
@@ -193,7 +193,7 @@ let
   }) latestCustomResourceTypes);
 
 in {
-  imports = [ ./base.nix ./submodules.nix ];
+  imports = [ ./base.nix ];
 
   options.kubernetes = {
     version = mkOption {
@@ -299,8 +299,38 @@ in {
     # expose k8s helper methods as module argument
     _module.args.k8s = import ../lib/k8s.nix { inherit lib; };
 
+    # features that module is defining
     _module.features = [ "k8s" ];
 
+    # module propagation options
+    _module.propagate = [{
+      features = ["k8s"];
+      module = { config, ... }: {
+        # propagate kubernetes version and namespace
+        kubernetes.version = mkDefault cfg.version;
+        kubernetes.namespace = mkDefault cfg.namespace;
+      };
+    } {
+      features = ["k8s" "submodule"];
+      module = { config, ... }: {
+        # set module defaults
+        kubernetes.api.defaults = (
+          # propagate defaults if default propagation is enabled
+          (filter (default: default.propagate) cfg.api.defaults) ++
+
+          [
+            # set module name and version for all kuberentes resources
+            {
+              default.metadata.labels = {
+                "kubenix/module-name" = config.submodule.name;
+                "kubenix/module-version" = config.submodule.version;
+              };
+            }
+          ]
+        );
+      };
+    }];
+
     kubernetes.api = mkMerge ([{
       # register custom types
       types = map (cr: {
@@ -309,18 +339,11 @@ in {
 
       defaults = [{
         default = {
+          # set default kubernetes namespace to all resources
           metadata.namespace = mkDefault config.kubernetes.namespace;
-          metadata.labels = mkMerge [
-            {
-              "kubenix/project-name" = config.kubenix.project;
-            }
 
-            # if we are inside submodule, define additional labels
-            (mkIf (elem "submodule" config._module.features) {
-              "kubenix/module-name" = config.submodule.name;
-              "kubenix/module-version" = config.submodule.version;
-            })
-          ];
+          # set project name to all resources
+          metadata.labels."kubenix/project-name" = config.kubenix.project;
         };
       }];
     }] ++
@@ -360,17 +383,5 @@ in {
       items = config.kubernetes.objects;
       labels."kubenix/project-name" = config.kubenix.project;
     };
-
-    submodules.defaults = [{
-      features = [ "k8s" ];
-      default = { config, name, ... }: {
-        # propagate kubernetes version and namespace
-        kubernetes.version = mkDefault cfg.version;
-        kubernetes.namespace = mkDefault cfg.namespace;
-
-        # propagate defaults if default propagation is enabled
-        kubernetes.api.defaults = filter (default: default.propagate) cfg.api.defaults;
-      };
-    }];
   };
 }
diff --git a/modules/submodules.nix b/modules/submodules.nix
index 4615edc..0081e04 100644
--- a/modules/submodules.nix
+++ b/modules/submodules.nix
@@ -215,18 +215,25 @@ in {
     default = {};
   };
 
-  config = mkMerge [
+  config = mkMerge ([
     {
       _module.features = ["submodules"];
 
       submodules.specialArgs.kubenix = kubenix;
 
       # passthru kubenix.project to submodules
-      submodules.defaults = [{
-        default = {
-          kubenix.project = parentConfig.kubenix.project;
-        };
-      }];
+      submodules.defaults = mkMerge [
+        [{
+          default = {
+            kubenix.project = parentConfig.kubenix.project;
+          };
+        }]
+
+        (map (propagate: {
+          features = propagate.features;
+          default = propagate.module;
+        }) config._module.propagate)
+      ];
     }
 
     (mkIf cfg.propagate.enable {