kubenix.submodule example used to create resources in multiple namespaces (#22)

docs/content/examples/namespaces/namespaced.nix

@@ -0,0 +1,64 @@
+{
+  config,
+  kubenix,
+  lib,
+  # Name of submodule instance.
+  name,
+  # This is a shorthand for config.submodule.args and contains
+  # final values of the args options.
+  args,
+  ...
+}: {
+  imports = with kubenix.modules; [
+    # This needs to be imported in order to define a submodule.
+    submodule
+    # Importing this so that we can set config.kubernetes
+    # within the context of this submodule.
+    k8s
+  ];
+
+  # Args are used to pass information from the parent context.
+  options.submodule.args = {
+    kubernetes = lib.mkOption {
+      description = "Kubernetes config to be applied to a specific namespace.";
+      # We are not given a precise type to this since we are using it
+      # to set kubernetes options from the k8s module which are already
+      # precisely typed.
+      type = lib.types.attrs;
+      default = {};
+    };
+  };
+
+  config = {
+    submodule = {
+      # Used to uniquely identify a submodule. Used to select submodule
+      # "prototype" when instantiating.
+      name = "namespaced";
+
+      # Passthru allows a submodule instance to set config of the parent
+      # context. It's not strictly required but it's useful for combining
+      # outputs of multiple submodule instances, without having to write
+      # ad hoc code in the parent context.
+
+      # NOTE: passthru has not effect if given options are not defined
+      # in the parent context. Therefore in this case we are expecting that
+      # parent imports kubinex.k8s module.
+
+      # Here we set kubernetes.objects.
+      # This is a list so even if distinct instances of the submodule contain
+      # definitions of identical api resources, these will not be merged or
+      # cause conflicts. Lists of resources from multiple submodule instances
+      # will simply be concatenated.
+      passthru.kubernetes.objects = config.kubernetes.objects;
+    };
+
+    kubernetes = lib.mkMerge [
+      # Use instance name as namespace
+      { namespace = name; }
+      # Create namespace object
+      { resources.namespaces.${name} = {}; }
+      # All resources defined here will use the above namespace
+      args.kubernetes
+    ];
+  };
+}