add localLookup/mustLocalLookup template functions in helm/kustomize generator

Author: cbarbian-sap

pkg/manifests/helm.go

@@ -44,14 +44,17 @@ type HelmGenerator struct {
 var _ Generator = &HelmGenerator{}
 
 // Create a new HelmGenerator.
-// Deprecation warning: the parameters name, client and discoveryClient are ignored (can be passed as empty resp. nil) and will be removed in a future release;
+// Deprecation warning: the parameters name and discoveryClient are ignored (can be passed as empty resp. nil) and will be removed in a future release;
 // the according values will be retrieved from the context passed to Generate().
+// The parameter client should be a client for the local cluster (i.e. the cluster where the component object resides);
+// it is used by the localLookup and mustLocalLookup template functions.
 // If fsys is nil, the local operating system filesystem will be used, and chartPath can be an absolute or relative path (in the latter case it will be considered
 // relative to the current working directory). If fsys is non-nil, then chartPath should be a relative path; if an absolute path is supplied, it will be turned
 // An empty chartPath will be treated like ".".
 func NewHelmGenerator(name string, fsys fs.FS, chartPath string, client client.Client, discoveryClient discovery.DiscoveryInterface) (*HelmGenerator, error) {
-	g := HelmGenerator{}
-	g.data = make(map[string]any)
+	g := HelmGenerator{
+		data: make(map[string]any),
+	}
 
 	if fsys == nil {
 		fsys = os.DirFS("/")
@@ -157,6 +160,7 @@ func NewHelmGenerator(name string, fsys fs.FS, chartPath string, client client.C
 				Funcs(sprig.TxtFuncMap()).
 				Funcs(templatex.FuncMap()).
 				Funcs(templatex.FuncMapForTemplate(t)).
+				Funcs(templatex.FuncMapForLocalClient(client)).
 				Funcs(templatex.FuncMapForClient(nil))
 		} else {
 			t = t.New(manifest)

pkg/manifests/kustomize.go

@@ -41,8 +41,8 @@ type KustomizeGenerator struct {
 var _ Generator = &KustomizeGenerator{}
 
 // Create a new KustomizeGenerator.
-// Deprecation warning: the parameter client is ignored (can be passed as nil) and will be removed in a future release;
-// the according value will be retrieved from the context passed to Generate().
+// The parameter client should be a client for the local cluster (i.e. the cluster where the component object resides);
+// it is used by the localLookup and mustLocalLookup template functions.
 // If fsys is nil, the local operating system filesystem will be used, and kustomizationPath can be an absolute or relative path (in the latter case it will be considered
 // relative to the current working directory). If fsys is non-nil, then kustomizationPath should be a relative path; if an absolute path is supplied, it will be turned
 // An empty kustomizationPath will be treated like ".".
@@ -71,6 +71,11 @@ func NewKustomizeGenerator(fsys fs.FS, kustomizationPath string, templateSuffix
 	g.kustomizer = krusty.MakeKustomizer(options)
 
 	var t *template.Template
+	// TODO: we should consider the whole of fsys, not only the subtree rooted at kustomizationPath;
+	// this would allow people to reference resources or patches or components located in parent directories
+	// (which is probably a common usecase); however it has to be clarified how to handle template scopes;
+	// for example it might be desired that subtrees with a kustomization.yaml file are processed in an own
+	// template context
 	files, err := find(fsys, kustomizationPath, "*", fileTypeRegular, 0)
 	if err != nil {
 		return nil, err
@@ -94,6 +99,7 @@ func NewKustomizeGenerator(fsys fs.FS, kustomizationPath string, templateSuffix
 					Funcs(sprig.TxtFuncMap()).
 					Funcs(templatex.FuncMap()).
 					Funcs(templatex.FuncMapForTemplate(t)).
+					Funcs(templatex.FuncMapForLocalClient(client)).
 					Funcs(templatex.FuncMapForClient(nil)).
 					Funcs(funcMapForGenerateContext(nil, "", ""))
 			} else {

website/content/en/docs/generators/helm.md

@@ -25,7 +25,8 @@ Here:
 - `name` is deprecated and will be removed in future releases; it can be passed as empty string.
 - `fsys` must be an implementation of `fs.FS`, such as `embed.FS`; or it can be passed as nil; then, all file operations will be executed on the current OS filesystem.
 - `chartPath` is the path containing the used Helm chart; if `fsys` was provided, this has to be a relative path; otherwise, it will be interpreted with respect to the OS filesystem (as an absolute path, or relative to the current working directory of the controller).
-- `client` and `discoveryClient` are deprecated and will be removed in future releases; they can be passed as nil.
+- `client` should be a client for the local cluster (i.e. the cluster where the component object exists).
+- `discoveryClient` is deprecated and will be removed in future releases; they can be passed as nil.
 
 It should be noted that `HelmGenerator` does not use the Helm SDK; instead it tries to emulate the Helm behavior as good as possible.
 A few differences and restrictions arise from this:

website/content/en/docs/generators/kustomize.md

@@ -32,4 +32,4 @@ Here:
 - `fsys` must be an implementation of `fs.FS`, such as `embed.FS`; or it can be passed as nil; then, all file operations will be executed on the current OS filesystem.
 - `kustomizationPath` is the path containing the (potentially templatized) kustomatization; if `fsys` was provided, this has to be a relative path; otherwise, it will be interpreted with respect to the OS filesystem (as an absolute path, or relative to the current working directory of the controller).
 - `templateSuffx` is optional; if empty, all files under `kustomizationPath` will be subject to go templating; otherwise, only files matching the specified suffix will be considered as templates.
-- `client` is deprecated and will be removed in future releases; it can be passed as nil.
+- `client` should be a client for the local cluster (i.e. the cluster where the component object exists).