Add `kubectl` hooks for applying file(s) or kustomize (#1736)

This enables you to write a `kubectl-apply` hook more declaratively than writing `command` and `args`:

```
releases:
- name: myapp
  chart: mychart
  hooks:
  - events: ["presync"]
    kubectlApply:
      filename: path/to/manifests
      #kustomize: path/to/kustomize
```

pkg/event/bus.go

@@ -12,11 +12,12 @@ import (
 )
 
 type Hook struct {
-	Name     string   `yaml:"name"`
-	Events   []string `yaml:"events"`
-	Command  string   `yaml:"command"`
-	Args     []string `yaml:"args"`
-	ShowLogs bool     `yaml:"showlogs"`
+	Name     string            `yaml:"name"`
+	Events   []string          `yaml:"events"`
+	Command  string            `yaml:"command"`
+	Kubectl  map[string]string `yaml:"kubectlApply,omitempty"`
+	Args     []string          `yaml:"args"`
+	ShowLogs bool              `yaml:"showlogs"`
 }
 
 type event struct {
@@ -61,7 +62,28 @@ func (bus *Bus) Trigger(evt string, evtErr error, context map[string]interface{}
 
 		name := hook.Name
 		if name == "" {
-			name = hook.Command
+			if hook.Kubectl != nil {
+				name = "kubectlApply"
+			} else {
+				name = hook.Command
+			}
+		}
+
+		if hook.Kubectl != nil {
+			if hook.Command != "" {
+				bus.Logger.Warnf("warn: ignoring command '%s' given within a kubectlApply hook", hook.Command)
+			}
+			hook.Command = "kubectl"
+			if val, found := hook.Kubectl["filename"]; found {
+				if _, found := hook.Kubectl["kustomize"]; found {
+					return false, fmt.Errorf("hook[%s]: kustomize & filename cannot be used together", name)
+				}
+				hook.Args = append([]string{"apply", "-f"}, val)
+			} else if val, found := hook.Kubectl["kustomize"]; found {
+				hook.Args = append([]string{"apply", "-k"}, val)
+			} else {
+				return false, fmt.Errorf("hook[%s]: either kustomize or filename must be given", name)
+			}
 		}
 
 		fmt.Fprintf(os.Stderr, "%s: basePath=%s\n", bus.StateFilePath, bus.BasePath)

pkg/event/bus_test.go

@@ -43,21 +43,21 @@ func TestTrigger(t *testing.T) {
 	}{
 		{
 			"okhook1",
-			&Hook{"okhook1", []string{"foo"}, "ok", []string{}, true},
+			&Hook{"okhook1", []string{"foo"}, "ok", nil, []string{}, true},
 			"foo",
 			true,
 			"",
 		},
 		{
 			"okhooké",
-			&Hook{"okhook2", []string{"foo"}, "ok", []string{}, false},
+			&Hook{"okhook2", []string{"foo"}, "ok", nil, []string{}, false},
 			"foo",
 			true,
 			"",
 		},
 		{
 			"missinghook1",
-			&Hook{"okhook1", []string{"foo"}, "ok", []string{}, false},
+			&Hook{"okhook1", []string{"foo"}, "ok", nil, []string{}, false},
 			"bar",
 			false,
 			"",
@@ -71,18 +71,74 @@ func TestTrigger(t *testing.T) {
 		},
 		{
 			"nghook1",
-			&Hook{"nghook1", []string{"foo"}, "ng", []string{}, false},
+			&Hook{"nghook1", []string{"foo"}, "ng", nil, []string{}, false},
 			"foo",
 			false,
 			"hook[nghook1]: command `ng` failed: cmd failed due to invalid cmd: ng",
 		},
 		{
 			"nghook2",
-			&Hook{"nghook2", []string{"foo"}, "ok", []string{"ng"}, false},
+			&Hook{"nghook2", []string{"foo"}, "ok", nil, []string{"ng"}, false},
 			"foo",
 			false,
 			"hook[nghook2]: command `ok` failed: cmd failed due to invalid arg: ng",
 		},
+		{
+			"okkubeapply1",
+			&Hook{"okkubeapply1", []string{"foo"}, "", map[string]string{"kustomize": "kustodir"}, []string{}, false},
+			"foo",
+			true,
+			"",
+		},
+		{
+			"okkubeapply2",
+			&Hook{"okkubeapply2", []string{"foo"}, "", map[string]string{"filename": "resource.yaml"}, []string{}, false},
+			"foo",
+			true,
+			"",
+		},
+		{
+			"kokubeapply",
+			&Hook{"kokubeapply", []string{"foo"}, "", map[string]string{"kustomize": "kustodir", "filename": "resource.yaml"}, []string{}, true},
+			"foo",
+			false,
+			"hook[kokubeapply]: kustomize & filename cannot be used together",
+		},
+		{
+			"kokubeapply2",
+			&Hook{"kokubeapply2", []string{"foo"}, "", map[string]string{}, []string{}, true},
+			"foo",
+			false,
+			"hook[kokubeapply2]: either kustomize or filename must be given",
+		},
+		{
+			"kokubeapply3",
+			&Hook{"", []string{"foo"}, "", map[string]string{}, []string{}, true},
+			"foo",
+			false,
+			"hook[kubectlApply]: either kustomize or filename must be given",
+		},
+		{
+			"warnkubeapply1",
+			&Hook{"warnkubeapply1", []string{"foo"}, "ok", map[string]string{"filename": "resource.yaml"}, []string{}, true},
+			"foo",
+			true,
+			"",
+		},
+		{
+			"warnkubeapply2",
+			&Hook{"warnkubeapply2", []string{"foo"}, "", map[string]string{"filename": "resource.yaml"}, []string{"ng"}, true},
+			"foo",
+			true,
+			"",
+		},
+		{
+			"warnkubeapply3",
+			&Hook{"warnkubeapply3", []string{"foo"}, "ok", map[string]string{"filename": "resource.yaml"}, []string{"ng"}, true},
+			"foo",
+			true,
+			"",
+		},
 	}
 	readFile := func(filename string) ([]byte, error) {
 		return nil, fmt.Errorf("unexpected call to readFile: %s", filename)
@@ -117,7 +173,7 @@ func TestTrigger(t *testing.T) {
 
 		if c.expectedErr != "" {
 			if err == nil {
-				t.Error("error expected, but not occurred")
+				t.Errorf("error expected for case \"%s\", but not occurred", c.name)
 			} else if err.Error() != c.expectedErr {
 				t.Errorf("unexpected error for case \"%s\": expected=%s, actual=%v", c.name, c.expectedErr, err)
 			}