WIP: Prebuild Stage Feature

api/v1beta1/kustomization_types.go

@@ -70,6 +70,11 @@ type KustomizationSpec struct {
 	// +optional
 	Path string `json:"path,omitempty"`
 
+	// PreBuild describes which actions to perform on the YAML manifest
+	// before it is built by the kustomize overlay.
+	// +optional
+	PreBuild *PreBuild `json:"preBuild,omitempty"`
+
 	// PostBuild describes which actions to perform on the YAML manifest
 	// generated by building the kustomize overlay.
 	// +optional
@@ -191,6 +196,26 @@ type PostBuild struct {
 	SubstituteFrom []SubstituteReference `json:"substituteFrom,omitempty"`
 }
 
+// Prebuild describes which actions to perform on the YAML manifest
+// generated by building the kustomize overlay.
+type PreBuild struct {
+	// Substitute holds a map of key/value pairs.
+	// The variables defined in your YAML manifests
+	// that match any of the keys defined in the map
+	// will be substituted with the set value.
+	// Includes support for bash string replacement functions
+	// e.g. ${var:=default}, ${var:position} and ${var/substring/replacement}.
+	// +optional
+	Substitute map[string]string `json:"substitute,omitempty"`
+
+	// SubstituteFrom holds references to ConfigMaps and Secrets containing
+	// the variables and their values to be substituted in the YAML manifests.
+	// The ConfigMap and the Secret data keys represent the var names and they
+	// must match the vars declared in the manifests for the substitution to happen.
+	// +optional
+	SubstituteFrom []SubstituteReference `json:"substituteFrom,omitempty"`
+}
+
 // SubstituteReference contains a reference to a resource containing
 // the variables name and value.
 type SubstituteReference struct {

config/crd/bases/kustomize.toolkit.fluxcd.io_kustomizations.yaml

@@ -275,6 +275,36 @@ spec:
                       type: object
                     type: array
                 type: object
+              preBuild:
+                description: PreBuild describes which actions to perform on the YAML manifest before it is built by the kustomize overlay.
+                properties:
+                  substitute:
+                    additionalProperties:
+                      type: string
+                    description: Substitute holds a map of key/value pairs. The variables defined in your YAML manifests that match any of the keys defined in the map will be substituted with the set value. Includes support for bash string replacement functions e.g. ${var:=default}, ${var:position} and ${var/substring/replacement}.
+                    type: object
+                  substituteFrom:
+                    description: SubstituteFrom holds references to ConfigMaps and Secrets containing the variables and their values to be substituted in the YAML manifests. The ConfigMap and the Secret data keys represent the var names and they must match the vars declared in the manifests for the substitution to happen.
+                    items:
+                      description: SubstituteReference contains a reference to a resource containing the variables name and value.
+                      properties:
+                        kind:
+                          description: Kind of the values referent, valid values are ('Secret', 'ConfigMap').
+                          enum:
+                          - Secret
+                          - ConfigMap
+                          type: string
+                        name:
+                          description: Name of the values referent. Should reside in the same namespace as the referring resource.
+                          maxLength: 253
+                          minLength: 1
+                          type: string
+                      required:
+                      - kind
+                      - name
+                      type: object
+                    type: array
+                type: object
               prune:
                 description: Prune enables garbage collection.
                 type: boolean

controllers/kustomization_controller.go

@@ -265,6 +265,7 @@ func (r *KustomizationReconciler) reconcile(
 	ctx context.Context,
 	kustomization kustomizev1.Kustomization,
 	source sourcev1.Source) (kustomizev1.Kustomization, error) {
+
 	// record the value of the reconciliation request, if any
 	if v, ok := meta.ReconcileAnnotationValue(kustomization.GetAnnotations()); ok {
 		kustomization.Status.SetLastHandledReconcileRequest(v)
@@ -500,7 +501,7 @@ func (r *KustomizationReconciler) getSource(ctx context.Context, kustomization k
 
 func (r *KustomizationReconciler) generate(ctx context.Context, kubeClient client.Client, kustomization kustomizev1.Kustomization, dirPath string) (string, error) {
 	gen := NewGenerator(kustomization, kubeClient)
-	return gen.WriteFile(ctx, dirPath)
+	return gen.WriteFile(ctx, dirPath, kubeClient, kustomization)
 }
 
 func (r *KustomizationReconciler) build(ctx context.Context, kustomization kustomizev1.Kustomization, checksum, dirPath string) (*kustomizev1.Snapshot, error) {

controllers/kustomization_generator.go

@@ -57,7 +57,7 @@ func NewGenerator(kustomization kustomizev1.Kustomization, kubeClient client.Cli
 	}
 }
 
-func (kg *KustomizeGenerator) WriteFile(ctx context.Context, dirPath string) (string, error) {
+func (kg *KustomizeGenerator) WriteFile(ctx context.Context, dirPath string, kubeClient client.Client, kustomization kustomizev1.Kustomization) (string, error) {
 	kfile := filepath.Join(dirPath, konfig.DefaultKustomizationFileName())
 
 	checksum, err := kg.checksum(ctx, dirPath)
@@ -140,6 +140,15 @@ func (kg *KustomizeGenerator) WriteFile(ctx context.Context, dirPath string) (st
 		}
 	}
 
+	// if prebuild is specified, substitude kustomization with given variables
+	// and return resulting kustomization
+	if kustomization.Spec.PreBuild != nil {
+		kus, err = preSubstituteVariables(ctx, kubeClient, kustomization, kus)
+		if err != nil {
+			return "", fmt.Errorf("var substitution failed for '%s'", err)
+		}
+	}
+
 	kd, err := yaml.Marshal(kus)
 	if err != nil {
 		return "", err
@@ -158,14 +167,14 @@ func checkKustomizeImageExists(images []kustypes.Image, imageName string) (bool,
 	return false, -1
 }
 
-func (kg *KustomizeGenerator) generateKustomization(dirPath string) error {
+func (kg *KustomizeGenerator) generateKustomization(dirPath string) (string, error) {
 	fs := filesys.MakeFsOnDisk()
 
 	// Determine if there already is a Kustomization file at the root,
 	// as this means we do not have to generate one.
 	for _, kfilename := range konfig.RecognizedKustomizationFileNames() {
 		if kpath := filepath.Join(dirPath, kfilename); fs.Exists(kpath) && !fs.IsDir(kpath) {
-			return nil
+			return kpath, nil
 		}
 	}
 
@@ -213,18 +222,18 @@ func (kg *KustomizeGenerator) generateKustomization(dirPath string) error {
 
 	abs, err := filepath.Abs(dirPath)
 	if err != nil {
-		return err
+		return "", err
 	}
 
 	files, err := scan(abs)
 	if err != nil {
-		return err
+		return "", err
 	}
 
 	kfile := filepath.Join(dirPath, konfig.DefaultKustomizationFileName())
 	f, err := fs.Create(kfile)
 	if err != nil {
-		return err
+		return "", err
 	}
 	f.Close()
 
@@ -243,17 +252,40 @@ func (kg *KustomizeGenerator) generateKustomization(dirPath string) error {
 	kus.Resources = resources
 	kd, err := yaml.Marshal(kus)
 	if err != nil {
-		return err
+		return "", err
 	}
 
-	return ioutil.WriteFile(kfile, kd, os.ModePerm)
+	return kfile, ioutil.WriteFile(kfile, kd, os.ModePerm)
 }
 
 func (kg *KustomizeGenerator) checksum(ctx context.Context, dirPath string) (string, error) {
-	if err := kg.generateKustomization(dirPath); err != nil {
+	kf, err := kg.generateKustomization(dirPath)
+	if err != nil {
 		return "", fmt.Errorf("kustomize create failed: %w", err)
 	}
 
+	// Run PreBuild Variable Substitution
+	if kg.kustomization.Spec.PreBuild != nil {
+		content, err := ioutil.ReadFile(kf)
+		if err != nil {
+			return "", fmt.Errorf("kustomize prebuild failed: %w", err)
+		}
+
+		kd := kustypes.Kustomization{}
+		err = yaml.Unmarshal(content, &kd)
+		if err != nil {
+			return "", fmt.Errorf("kustomize prebuild failed: %w", err)
+		}
+
+		kd, err = preSubstituteVariables(ctx, kg.Client, kg.kustomization, kd)
+		if err != nil {
+			return "", fmt.Errorf("var substitution failed for '%s'", err)
+		}
+
+		kdYaml, err := yaml.Marshal(kd)
+		ioutil.WriteFile(kf, kdYaml, os.ModePerm)
+	}
+
 	fs := filesys.MakeFsOnDisk()
 	m, err := buildKustomization(fs, dirPath)
 	if err != nil {

controllers/kustomization_varsub.go

@@ -7,42 +7,31 @@ import (
 	"strings"
 
 	"github.com/drone/envsubst"
+	kustomizev1 "github.com/fluxcd/kustomize-controller/api/v1beta1"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/types"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/kustomize/api/resource"
+	kustypes "sigs.k8s.io/kustomize/api/types"
 	"sigs.k8s.io/yaml"
-
-	kustomizev1 "github.com/fluxcd/kustomize-controller/api/v1beta1"
 )
 
 // varsubRegex is the regular expression used to validate
 // the var names before substitution
 const varsubRegex = "^[_[:alpha:]][_[:alpha:][:digit:]]*$"
 
-// substituteVariables replaces the vars with their values in the specified resource.
-// If a resource is labeled or annotated with
-// 'kustomize.toolkit.fluxcd.io/substitute: disabled' the substitution is skipped.
-func substituteVariables(
+// substitudeFrom loads vars from configmaps and secrets referenced
+// in the given SubstituteReference
+func substitudeFrom(
 	ctx context.Context,
 	kubeClient client.Client,
 	kustomization kustomizev1.Kustomization,
-	res *resource.Resource) (*resource.Resource, error) {
-	resData, err := res.AsYAML()
-	if err != nil {
-		return nil, err
-	}
-
-	key := fmt.Sprintf("%s/substitute", kustomizev1.GroupVersion.Group)
-
-	if res.GetLabels()[key] == kustomizev1.DisabledValue || res.GetAnnotations()[key] == kustomizev1.DisabledValue {
-		return nil, nil
-	}
-
+	substituteReference []kustomizev1.SubstituteReference) (map[string]string, error) {
+	// placeholder variable for returnable substitutions
 	vars := make(map[string]string)
 
 	// load vars from ConfigMaps and Secrets data keys
-	for _, reference := range kustomization.Spec.PostBuild.SubstituteFrom {
+	for _, reference := range substituteReference {
 		namespacedName := types.NamespacedName{Namespace: kustomization.Namespace, Name: reference.Name}
 		switch reference.Kind {
 		case "ConfigMap":
@@ -63,6 +52,87 @@ func substituteVariables(
 			}
 		}
 	}
+	return vars, nil
+}
+
+// substituteVariables replaces the vars with their values in the specified resource.
+// If a resource is labeled or annotated with
+func preSubstituteVariables(
+	ctx context.Context,
+	kubeClient client.Client,
+	kustomization kustomizev1.Kustomization,
+	kustomizeFile kustypes.Kustomization) (kustypes.Kustomization, error) {
+	kd := kustypes.Kustomization{}
+	kustomizeData, err := yaml.Marshal(kustomizeFile)
+	if err != nil {
+		return kd, err
+	}
+
+	// load vars from ConfigMaps and Secrets data keys
+	vars, err := substitudeFrom(ctx, kubeClient, kustomization, kustomization.Spec.PreBuild.SubstituteFrom)
+	if err != nil {
+		return kd, err
+	}
+
+	// load in-line vars (overrides the ones from resources)
+	if kustomization.Spec.PreBuild.Substitute != nil {
+		for k, v := range kustomization.Spec.PreBuild.Substitute {
+			vars[k] = strings.Replace(v, "\n", "", -1)
+		}
+	}
+
+	// run bash variable substitutions
+	r, _ := regexp.Compile(varsubRegex)
+	for v := range vars {
+		if !r.MatchString(v) {
+			return kd, fmt.Errorf("'%s' var name is invalid, must match '%s'", v, varsubRegex)
+		}
+	}
+
+	output, err := envsubst.Eval(string(kustomizeData), func(s string) string {
+		return vars[s]
+	})
+	if err != nil {
+		return kd, fmt.Errorf("variable substitution failed: %w", err)
+	}
+
+	json, err := yaml.YAMLToJSON([]byte(output))
+	if err != nil {
+		return kd, fmt.Errorf("Prebuild variable substitution failed: %w", err)
+	}
+
+	err = yaml.Unmarshal(json, &kd)
+	if err != nil {
+		return kd, err
+	}
+
+	return kd, nil
+}
+
+// substituteVariables replaces the vars with their values in the specified resource.
+// If a resource is labeled or annotated with
+// 'kustomize.toolkit.fluxcd.io/substitute: disabled' the substitution is skipped.
+func substituteVariables(
+	ctx context.Context,
+	kubeClient client.Client,
+	kustomization kustomizev1.Kustomization,
+	res *resource.Resource) (*resource.Resource, error) {
+	resData, err := res.AsYAML()
+	if err != nil {
+		return nil, err
+	}
+
+	key := fmt.Sprintf("%s/substitute", kustomizev1.GroupVersion.Group)
+
+	if res.GetLabels()[key] == kustomizev1.DisabledValue || res.GetAnnotations()[key] == kustomizev1.DisabledValue {
+		return nil, nil
+	}
+
+	// load vars from ConfigMaps and Secrets data keys
+	vars, err := substitudeFrom(ctx, kubeClient, kustomization, kustomization.Spec.PostBuild.SubstituteFrom)
+	if err != nil {
+		return nil, err
+	}
 
 	// load in-line vars (overrides the ones from resources)
 	if kustomization.Spec.PostBuild.Substitute != nil {