feat: implement all (?) ci yaml keywords

lib/impl/modules/pipeline.nix

@@ -4,8 +4,8 @@
   jobSubmodule,
   ...
 }: let
-  inherit (lib) mkOption types filterAttrs mergeAttrsList mapAttrs;
-  inherit (cilib.helpers) filterUnset mkUnsetOption toYaml toYamlPretty;
+  inherit (lib) mkOption types filterAttrs mergeAttrsList mapAttrs mkRenamedOptionModule literalExpression;
+  inherit (cilib.helpers) filterUnset unset mkUnsetOption toYaml toYamlPretty eitherWithSubOptions;
 
   pipelineConfigSubmodule = {rootConfig, ...}: {
     options = {
@@ -30,19 +30,143 @@
     # GITLAB OPTIONS
     #
     gitlabOptions = {
+      default = mkOption {
+        type = types.submodule {
+          # allow other keys aswell, maybe define them in the future? https://docs.gitlab.com/ci/yaml/#default
+          freeformType = types.anything;
+          options = {
+            image = mkUnsetOption {
+              type = types.str;
+              description = ''
+                Default image to use for this entire pipeline.
+
+                !!! note
+                    Moved from top level to `default`: [GitLab Docs](https://docs.gitlab.com/ci/yaml/deprecated_keywords/).
+              '';
+            };
+            services = mkUnsetOption {
+              type = types.listOf types.anything;
+              description = ''
+                !!! note
+                    Moved from top level to `default`: [GitLab Docs](https://docs.gitlab.com/ci/yaml/deprecated_keywords/).
+              '';
+            };
+            cache = mkUnsetOption {
+              # could be more granular
+              type = types.either (types.listOf types.attrs) types.attrs;
+              description = ''
+                !!! note
+                    Moved from top level to `default`: [GitLab Docs](https://docs.gitlab.com/ci/yaml/deprecated_keywords/).
+              '';
+            };
+            before_script = mkUnsetOption {
+              type = types.listOf types.str;
+              description = ''
+                !!! note
+                    Moved from top level to `default`: [GitLab Docs](https://docs.gitlab.com/ci/yaml/deprecated_keywords/).
+              '';
+            };
+            after_script = mkUnsetOption {
+              type = types.listOf types.str;
+              description = ''
+                !!! note
+                    Moved from top level to `default`: [GitLab Docs](https://docs.gitlab.com/ci/yaml/deprecated_keywords/).
+              '';
+            };
+          };
+        };
+        # required for it to show up in the docs, but not in the config
+        default = unset;
+        defaultText = literalExpression "unset";
+        description = ''
+          Custom default values for job keywords.
+        '';
+      };
+      include = mkUnsetOption {
+        type = types.attrs;
+        description = ''
+          Import configuration from other YAML files.
+
+          [Docs](https://docs.gitlab.com/ci/yaml/#include)
+        '';
+      };
       stages = mkOption {
         type = types.listOf types.str;
         default = [];
         # .pre and .post always exist
         apply = val: [".pre"] ++ val ++ [".post"];
+        description = ''
+          The names and order of the pipeline stages.
+
+          [Docs](https://docs.gitlab.com/ci/yaml/#stages)
+
+          !!! note
+              `.pre` and `.post` are added automatically.
+        '';
       };
       variables = mkUnsetOption {
-        type = types.attrsOf types.str;
-        description = '''';
+        # default/global variables can have descriptions etc.
+        type = types.attrsOf (eitherWithSubOptions types.str (types.submodule {
+          options = {
+            description = mkUnsetOption {
+              type = types.str;
+              description = ''
+                Use the `description` keyword to define a description for a default variable.
+              '';
+            };
+            value = mkUnsetOption {
+              type = types.str;
+              description = ''
+                Use the `value` keyword to define a pipeline-level (default) variable’s value.
+              '';
+            };
+            options = mkUnsetOption {
+              type = types.listOf types.str;
+              description = ''
+                Use `options` to define an array of values that are [selectable in the UI when running a pipeline manually](https://docs.gitlab.com/ci/pipelines/#configure-a-list-of-selectable-prefilled-variable-values).
+              '';
+            };
+            expand = mkUnsetOption {
+              type = types.bool;
+              description = ''
+                Use the `expand` keyword to configure a variable to be expandable or not.
+              '';
+            };
+          };
+        }));
+        description = ''
+          Define default CI/CD variables for all jobs in the pipeline.
+          Supports strings or attrs as values, for more info see [here](https://docs.gitlab.com/ci/yaml/#variablesdescription).
+
+          [Docs](https://docs.gitlab.com/ci/yaml/#default-variables)
+        '';
+      };
+      workflow = mkUnsetOption {
+        type = types.attrs;
+        description = ''
+          Control what types of pipeline run.
+
+          [Docs](https://docs.gitlab.com/ci/yaml/#workflow)
+        '';
       };
     };
   in {
     _file = ./pipeline.nix;
+    # from https://docs.gitlab.com/ci/yaml/#default
+    imports = builtins.map (val: mkRenamedOptionModule [val] ["default" val]) [
+      "after_script"
+      "artifacts"
+      "before_script"
+      "cache"
+      "hooks"
+      "id_tokens"
+      "image"
+      "interruptible"
+      "retry"
+      "services"
+      "tags"
+      "timeout"
+    ];
     options =
       {
         nix = mkOption {