Add support for Kustomize Transformers (#1592)

Please see the updated `advanced-features.md` for more details.

This is often used for adding common labels and annotations to any resources rendered from a Helm chart.

docs/advanced-features.md

@@ -1,6 +1,8 @@
 ## Advanced Features
 
 - [Import Configuration Parameters into Helmfile](#import-configuration-parameters-into-helmfile)
+- [Deploy Kustomization with Helmfile](#deploy-kustomizations-with-helmfile)
+- [Adhoc Kustomization of Helm Charts](#adhoc-kustomization-of-helm-charts)
 
 ### Import Configuration Parameters into Helmfile
 
@@ -35,7 +37,7 @@ $ somehow_generate_chart_yaml ${TMPCHART}/Chart.yaml
 
 $ TMPKUSTOMIZATION=/tmp/sometmpdir2
 $ somehow_generate_temp_kustomization_yaml ${TMPKUSTOMIZATION}/kustomization.yaml
-$ kustomize build ${TMPKUSTOMIZATION}/kustomization.yaml > ${TMPCHART}/templates/all.yaml 
+$ kustomize build ${TMPKUSTOMIZATION}/kustomization.yaml > ${TMPCHART}/templates/all.yaml
 ```
 
 Let's say you have a `helmfile.yaml` that looks like the below:
@@ -57,7 +59,7 @@ bases:
 
 Followed by the below steps:
 
-- Running `kustomize edit set image $IMAGE` for every `$IMAGE` generated from your values.yaml 
+- Running `kustomize edit set image $IMAGE` for every `$IMAGE` generated from your values.yaml
 - Running `kustomize edit set nameprefix $NAMEPREFIX` with the nameprefix specified in your values.yaml
 - Running `kustomize edit set namesuffix $NAMESUFFIX` with the namesuffix specified in your values.yaml
 - Running `kustomize edit set namespace $NS` with the namespace specified in your values.yaml
@@ -92,7 +94,17 @@ After all, Helmfile just installs the temporary chart like standard charts, whic
 
 Please also see [test/advanced/helmfile.yaml](https://github.com/roboll/helmfile/tree/master/test/advanced/helmfile.yaml) for an example of kustomization support and more.
 
-## Adhoc Customization of Helm charts
+### Adhoc Kustomization of Helm charts
+
+With Helmfile's integration with Helmfile, not only deploying Kustomization as a Helm chart, you can kustomize charts before installation.
+
+Currently, Helmfile allows you to set the following fields for kustomizing the chart:
+
+- [`releases[].strategicMergePatches`](#strategicmergepatches)
+- `releases[].jsonPatches`
+- [`releases[].transformers`](#transformers)
+
+#### `strategicMergePatches`
 
 You can add/update any Kubernetes resource field rendered from a Helm chart by specifying `releases[].strategicMergePatches`:
 
@@ -135,3 +147,65 @@ Please note that the second `data` field `bar` is coming from the strategic-merg
 There's also `releases[].jsonPatches` that works similarly to `strategicMergePatches` but has additional capability to remove fields.
 
 Please also see [test/advanced/helmfile.yaml](https://github.com/roboll/helmfile/tree/master/test/advanced/helmfile.yaml) for an example of patching support and more.
+
+#### `transformers`
+
+You can set `transformers` to apply [Kustomize's transformers](https://github.com/kubernetes-sigs/kustomize/blob/master/examples/configureBuiltinPlugin.md#configuring-the-builtin-plugins-instead).
+
+Each item can be a path to a YAML or go template file, or an embedded transformer declaration as a YAML hash.
+
+It's often used to add common labels and annotations to your resources.
+
+In the below example. we add common annotations and labels every resource rendered from the `aws-load-balancer-controller` chart:
+
+```yaml
+releases:
+- name: "aws-load-balancer-controller"
+  namespace: "kube-system"
+  forceNamespace: "kube-system"
+  chart: "center/aws/aws-load-balancer-controller"
+  transformers:
+  - apiVersion: builtin
+    kind: AnnotationsTransformer
+    metadata:
+      name: notImportantHere
+    annotations:
+      area: 51
+      greeting: take me to your leader
+    fieldSpecs:
+    - path: metadata/annotations
+      create: true
+  - apiVersion: builtin
+    kind: LabelTransformer
+    metadata:
+      name: notImportantHere
+    labels:
+      foo: bar
+    fieldSpecs:
+    - path: metadata/labels
+      create: true
+```
+
+As explained earlier, `transformers` can be not only a list of embedded transformers, but also YAML or go template files, or a mix of those three kinds.
+
+```yaml
+transformers:
+# Embedded transformer
+- apiVersion: builtin
+  kind: AnnotationsTransformer
+  metadata:
+    name: notImportantHere
+  annotations:
+    area: 51
+    greeting: take me to your leader
+  fieldSpecs:
+  - path: metadata/annotations
+    create: true
+# YAML file
+- path/to/transformer.yaml
+# Go template
+# The same set of template parameters as release values files templates is available.
+- path/to/transformer.yaml.gotmpl
+```
+
+Please see https://github.com/kubernetes-sigs/kustomize/blob/master/examples/configureBuiltinPlugin.md#configuring-the-builtin-plugins-instead for more information on how to declare transformers.

go.mod

@@ -23,7 +23,7 @@ require (
 	github.com/spf13/cobra v1.1.1
 	github.com/tatsushid/go-prettytable v0.0.0-20141013043238-ed2d14c29939
 	github.com/urfave/cli v1.22.5
-	github.com/variantdev/chartify v0.4.9
+	github.com/variantdev/chartify v0.5.0
 	github.com/variantdev/dag v0.0.0-20191028002400-bb0b3c785363
 	github.com/variantdev/vals v0.11.0
 	go.uber.org/multierr v1.6.0

go.sum

@@ -622,6 +622,8 @@ github.com/urfave/cli v1.22.5 h1:lNq9sAHXK2qfdI8W+GRItjCEkI+2oR4d+MEHy1CKXoU=
 github.com/urfave/cli v1.22.5/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
 github.com/variantdev/chartify v0.4.9 h1:06foIMnJj31q/l1JZ+54anDLwqtP8zAOv5qVEn2IQhM=
 github.com/variantdev/chartify v0.4.9/go.mod h1:jqlUJIzcrIVSfg8FC4g+IoC5WB83TBl8rnVVEv6g8MQ=
+github.com/variantdev/chartify v0.5.0 h1:I6T6oobjLfYmwZ4dUjRsO9AdGKPCMtfzt0CXR0ovl9k=
+github.com/variantdev/chartify v0.5.0/go.mod h1:jqlUJIzcrIVSfg8FC4g+IoC5WB83TBl8rnVVEv6g8MQ=
 github.com/variantdev/dag v0.0.0-20191028002400-bb0b3c785363 h1:KrfQBEUn+wEOQ/6UIfoqRDvn+Q/wZridQ7t0G1vQqKE=
 github.com/variantdev/dag v0.0.0-20191028002400-bb0b3c785363/go.mod h1:pH1TQsNSLj2uxMo9NNl9zdGy01Wtn+/2MT96BrKmVyE=
 github.com/variantdev/vals v0.11.0 h1:818ztGk5yPTiixbUeE3LkkBGGATEAKtWq09n8q8PFqc=

pkg/state/helmx.go

@@ -144,6 +144,22 @@ func (st *HelmState) PrepareChartify(helm helmexec.Interface, release *ReleaseSp
 		shouldRun = true
 	}
 
+	transformers := release.Transformers
+	if len(transformers) > 0 {
+		generatedFiles, err := st.generateTemporaryReleaseValuesFiles(release, transformers, release.MissingFileHandler)
+		if err != nil {
+			return nil, clean, err
+		}
+
+		for _, f := range generatedFiles {
+			chartify.Opts.Transformers = append(chartify.Opts.Transformers, f)
+		}
+
+		filesNeedCleaning = append(filesNeedCleaning, generatedFiles...)
+
+		shouldRun = true
+	}
+
 	if release.ForceNamespace != "" {
 		chartify.Opts.OverrideNamespace = release.ForceNamespace
 

pkg/state/state.go

@@ -256,7 +256,14 @@ type ReleaseSpec struct {
 	Dependencies          []Dependency  `yaml:"dependencies,omitempty"`
 	JSONPatches           []interface{} `yaml:"jsonPatches,omitempty"`
 	StrategicMergePatches []interface{} `yaml:"strategicMergePatches,omitempty"`
-	Adopt                 []string      `yaml:"adopt,omitempty"`
+
+	// Transformers is the list of Kustomize transformers
+	//
+	// Each item can be a path to a YAML or go template file, or an embedded transformer declaration as a YAML hash.
+	// It's often used to add common labels and annotations to your resources.
+	// See https://github.com/kubernetes-sigs/kustomize/blob/master/examples/configureBuiltinPlugin.md#configuring-the-builtin-plugins-instead for more information.
+	Transformers []interface{} `yaml:"transformers,omitempty"`
+	Adopt        []string      `yaml:"adopt,omitempty"`
 
 	//version of the chart that has really been installed cause desired version may be fuzzy (~2.0.0)
 	installedVersion string