Allow functions to enable the starlark filter (off by default)

kyaml/kio/filters/functiontypes.go

@@ -25,6 +25,9 @@ type FunctionSpec struct {
 
 	// Container is the spec for running a function as a container
 	Container ContainerSpec `json:"container,omitempty" yaml:"container,omitempty"`
+
+	// Starlark is the spec for running a function as a starlark script
+	Starlark StarlarkSpec `json:"starlark,omitempty" yaml:"starlark,omitempty"`
 }
 
 // ContainerSpec defines a spec for running a function as a container
@@ -42,6 +45,14 @@ type ContainerNetwork struct {
 	Required bool `json:"required,omitempty" yaml:"required,omitempty"`
 }
 
+// StarlarkSpec defines how to run a function as a starlark program
+type StarlarkSpec struct {
+	Name string `json:"name,omitempty" yaml:"name,omitempty"`
+
+	// Path specifies a path to a starlark script
+	Path string `json:"path,omitempty" yaml:"path,omitempty"`
+}
+
 // GetFunctionSpec returns the FunctionSpec for a resource.  Returns
 // nil if the resource does not have a FunctionSpec.
 //

kyaml/runfn/runfn.go

@@ -15,6 +15,7 @@ import (
 	"sigs.k8s.io/kustomize/kyaml/kio"
 	"sigs.k8s.io/kustomize/kyaml/kio/filters"
 	"sigs.k8s.io/kustomize/kyaml/kio/kioutil"
+	"sigs.k8s.io/kustomize/kyaml/starlark"
 	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
@@ -57,6 +58,12 @@ type RunFns struct {
 	// and only use explicit sources
 	NoFunctionsFromInput *bool
 
+	// EnableStarlark will enable functions run as starlark scripts
+	EnableStarlark bool
+
+	// DisableContainers will disable functions run as containers
+	DisableContainers bool
+
 	// functionFilterProvider provides a filter to perform the function.
 	// this is a variable so it can be mocked in tests
 	functionFilterProvider func(
@@ -208,8 +215,10 @@ func (r RunFns) getFunctionFilters(global bool, fns ...*yaml.RNode) (
 			}
 			spec.Network = r.NetworkName
 		}
-
 		c := r.functionFilterProvider(*spec, api)
+		if c == nil {
+			continue
+		}
 		cf, ok := c.(*filters.ContainerFilter)
 		if global && ok {
 			cf.GlobalScope = true
@@ -291,7 +300,7 @@ func (r *RunFns) init() {
 
 // ffp provides function filters
 func (r *RunFns) ffp(spec filters.FunctionSpec, api *yaml.RNode) kio.Filter {
-	if spec.Container.Image != "" {
+	if !r.DisableContainers && spec.Container.Image != "" {
 		return &filters.ContainerFilter{
 			Image:         spec.Container.Image,
 			Config:        api,
@@ -300,9 +309,12 @@ func (r *RunFns) ffp(spec filters.FunctionSpec, api *yaml.RNode) kio.Filter {
 			GlobalScope:   r.GlobalScope,
 		}
 	}
-	return noOpFilter
+	if r.EnableStarlark && spec.Starlark.Path != "" {
+		return &starlark.Filter{
+			Name:           spec.Starlark.Name,
+			Path:           spec.Starlark.Path,
+			FunctionConfig: api,
+		}
+	}
+	return nil
 }
-
-var noOpFilter = kio.FilterFunc(func(in []*yaml.RNode) ([]*yaml.RNode, error) {
-	return in, nil
-})

kyaml/runfn/runfn_test.go

@@ -190,6 +190,10 @@ func TestRunFns_getFilters(t *testing.T) {
 		name string
 		// value to set for NoFunctionsFromInput
 		noFunctionsFromInput *bool
+
+		enableStarlark bool
+
+		disableContainers bool
 	}{
 		// Test
 		//
@@ -213,6 +217,26 @@ metadata:
 			out: []string{"gcr.io/example.com/image:v1.0.0"},
 		},
 
+		{name: "disable containers",
+			in: []f{
+				{
+					path: filepath.Join("foo", "bar.yaml"),
+					value: `
+apiVersion: example.com/v1alpha1
+kind: ExampleFunction
+metadata:
+  annotations:
+    config.kubernetes.io/function: |
+      container:
+        image: gcr.io/example.com/image:v1.0.0
+    config.kubernetes.io/local-config: "true"
+`,
+				},
+			},
+			out:               nil,
+			disableContainers: true,
+		},
+
 		// Test
 		//
 		//
@@ -432,6 +456,45 @@ metadata:
 			},
 			out: []string{"b", "a", "c"},
 		},
+
+		// Test
+		//
+		//
+		{name: "starlark-function",
+			in: []f{
+				{
+					path: filepath.Join("foo", "bar.yaml"),
+					value: `
+apiVersion: example.com/v1alpha1
+kind: ExampleFunction
+metadata:
+  annotations:
+    config.kubernetes.io/function: |
+      starlark:
+        path: a/b/c
+`,
+				},
+			},
+			enableStarlark: true,
+			out:            []string{"name:  path: a/b/c url:  program:"},
+		},
+
+		{name: "starlark-function-disabled",
+			in: []f{
+				{
+					path: filepath.Join("foo", "bar.yaml"),
+					value: `
+apiVersion: example.com/v1alpha1
+kind: ExampleFunction
+metadata:
+  annotations:
+    config.kubernetes.io/function: |
+      starlark:
+        path: a/b/c
+`,
+				},
+			},
+		},
 	}
 
 	for i := range tests {
@@ -484,6 +547,8 @@ metadata:
 
 			// init the instance
 			r := &RunFns{
+				EnableStarlark:       tt.enableStarlark,
+				DisableContainers:    tt.disableContainers,
 				FunctionPaths:        fnPaths,
 				Functions:            parsedFns,
 				Path:                 d,

kyaml/starlark/starlark.go

@@ -35,6 +35,10 @@ type Filter struct {
 	FunctionConfig *yaml.RNode
 }
 
+func (sf *Filter) String() string {
+	return fmt.Sprintf("name: %v path: %v url: %v program: %v", sf.Name, sf.Path, sf.URL, sf.Program)
+}
+
 func (sf *Filter) Filter(input []*yaml.RNode) ([]*yaml.RNode, error) {
 	if sf.URL != "" && sf.Path != "" ||
 		sf.URL != "" && sf.Program != "" ||