feat(template): added secret template function (#1221)

* feat(tmpl): added fetchSecretValue template function

This adds a tmpl `fetchSecretValue` and `expandSecretRefs` function by:
- Adding:
    - `expandSecretRefs` function in tmpl package that uses vals
    package to fetch secrets
    - `fetchSecretValue` function in tmpl package like below but for
    single string value
    - gomock for tests purpose
- Changing:
    - move init of vals package to function (so the same instance can be used for template values and rendering the whole template)

* doc(secret): added doc how to use new tmpl methods

Added example usage of `fetchSecretValue` and `expandSecretRefs`

pkg/tmpl/context_funcs.go

@@ -17,16 +17,18 @@ type Values = map[string]interface{}
 
 func (c *Context) createFuncMap() template.FuncMap {
 	funcMap := template.FuncMap{
-		"exec":           c.Exec,
-		"readFile":       c.ReadFile,
-		"toYaml":         ToYaml,
-		"fromYaml":       FromYaml,
-		"setValueAtPath": SetValueAtPath,
-		"requiredEnv":    RequiredEnv,
-		"get":            get,
-		"getOrNil":       getOrNil,
-		"tpl":            c.Tpl,
-		"required":       Required,
+		"exec":             c.Exec,
+		"readFile":         c.ReadFile,
+		"toYaml":           ToYaml,
+		"fromYaml":         FromYaml,
+		"setValueAtPath":   SetValueAtPath,
+		"requiredEnv":      RequiredEnv,
+		"get":              get,
+		"getOrNil":         getOrNil,
+		"tpl":              c.Tpl,
+		"required":         Required,
+		"fetchSecretValue": fetchSecretValue,
+		"expandSecretRefs": fetchSecretValues,
 	}
 	if c.preRender {
 		// disable potential side-effect template calls

pkg/tmpl/expand_secret_ref.go

@@ -0,0 +1,63 @@
+package tmpl
+
+import (
+	"errors"
+	"fmt"
+	"github.com/roboll/helmfile/pkg/plugins"
+	"github.com/variantdev/vals"
+	"sync"
+)
+
+//to generate mock run mockgen -source=expand_secret_ref.go -destination=expand_secrets_mock.go -package=tmpl
+type valClient interface {
+	Eval(template map[string]interface{}) (map[string]interface{}, error)
+}
+
+var once sync.Once
+var secretsClient valClient
+
+func fetchSecretValue(path string) (string, error) {
+	tmpMap := make(map[string]interface{})
+	tmpMap["key"] = path
+	resultMap, err := fetchSecretValues(tmpMap)
+	if err != nil {
+		return "", err
+	}
+
+	rendered, ok := resultMap["key"]
+	if !ok {
+		return "", errors.New(fmt.Sprintf("unexpected error occurred, %v doesn't have 'key' key", resultMap))
+	}
+
+	result, ok := rendered.(string)
+	if !ok {
+		return "", errors.New(fmt.Sprintf("expected %v to be string", rendered))
+	}
+
+	return result, nil
+}
+
+func fetchSecretValues(values map[string]interface{}) (map[string]interface{}, error) {
+	var err error
+	// below lines are for tests
+	once.Do(func() {
+		var valRuntime *vals.Runtime
+		if secretsClient == nil {
+			valRuntime, err = plugins.ValsInstance()
+			if err != nil {
+				return
+			}
+			secretsClient = valRuntime
+		}
+	})
+	if secretsClient == nil {
+		return nil, err
+	}
+
+	resultMap, err := secretsClient.Eval(values)
+	if err != nil {
+		return nil, err
+	}
+
+	return resultMap, nil
+}

pkg/tmpl/expand_secret_ref_test.go

@@ -0,0 +1,78 @@
+package tmpl
+
+import (
+	"errors"
+	"github.com/golang/mock/gomock"
+	"gotest.tools/assert"
+	"testing"
+)
+
+func Test_fetchSecretValue(t *testing.T) {
+	controller := gomock.NewController(t)
+	defer controller.Finish()
+	c := NewMockvalClient(controller)
+	secretsClient = c
+
+	secretPath := "ref+vault://key/#path"
+	expectArg := make(map[string]interface{})
+	expectArg["key"] = secretPath
+
+	valsResult := make(map[string]interface{})
+	valsResult["key"] = "key_value"
+	c.EXPECT().Eval(expectArg).Return(valsResult, nil)
+	result, err := fetchSecretValue(secretPath)
+	assert.NilError(t, err)
+	assert.Equal(t, result, "key_value")
+}
+
+func Test_fetchSecretValue_error(t *testing.T) {
+	controller := gomock.NewController(t)
+	defer controller.Finish()
+	c := NewMockvalClient(controller)
+	secretsClient = c
+
+	secretPath := "ref+vault://key/#path"
+	expectArg := make(map[string]interface{})
+	expectArg["key"] = secretPath
+
+	expectedErr := errors.New("some error")
+	c.EXPECT().Eval(expectArg).Return(nil, expectedErr)
+	result, err := fetchSecretValue(secretPath)
+	assert.Equal(t, err, expectedErr)
+	assert.Equal(t, result, "")
+}
+
+func Test_fetchSecretValue_no_key(t *testing.T) {
+	controller := gomock.NewController(t)
+	defer controller.Finish()
+	c := NewMockvalClient(controller)
+	secretsClient = c
+
+	secretPath := "ref+vault://key/#path"
+	expectArg := make(map[string]interface{})
+	expectArg["key"] = secretPath
+
+	valsResult := make(map[string]interface{})
+	c.EXPECT().Eval(expectArg).Return(valsResult, nil)
+	result, err := fetchSecretValue(secretPath)
+	assert.Error(t, err, "unexpected error occurred, map[] doesn't have 'key' key")
+	assert.Equal(t, result, "")
+}
+
+func Test_fetchSecretValue_invalid_type(t *testing.T) {
+	controller := gomock.NewController(t)
+	defer controller.Finish()
+	c := NewMockvalClient(controller)
+	secretsClient = c
+
+	secretPath := "ref+vault://key/#path"
+	expectArg := make(map[string]interface{})
+	expectArg["key"] = secretPath
+
+	valsResult := make(map[string]interface{})
+	valsResult["key"] = 10
+	c.EXPECT().Eval(expectArg).Return(valsResult, nil)
+	result, err := fetchSecretValue(secretPath)
+	assert.Error(t, err, "expected 10 to be string")
+	assert.Equal(t, result, "")
+}

pkg/tmpl/expand_secrets_mock.go

@@ -0,0 +1,45 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: expand_secret_ref.go
+
+package tmpl
+
+import (
+	gomock "github.com/golang/mock/gomock"
+	reflect "reflect"
+)
+
+// MockvalClient is a mock of valClient interface
+type MockvalClient struct {
+	ctrl     *gomock.Controller
+	recorder *MockvalClientMockRecorder
+}
+
+// MockvalClientMockRecorder is the mock recorder for MockvalClient
+type MockvalClientMockRecorder struct {
+	mock *MockvalClient
+}
+
+// NewMockvalClient creates a new mock instance
+func NewMockvalClient(ctrl *gomock.Controller) *MockvalClient {
+	mock := &MockvalClient{ctrl: ctrl}
+	mock.recorder = &MockvalClientMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use
+func (_m *MockvalClient) EXPECT() *MockvalClientMockRecorder {
+	return _m.recorder
+}
+
+// Eval mocks base method
+func (_m *MockvalClient) Eval(template map[string]interface{}) (map[string]interface{}, error) {
+	ret := _m.ctrl.Call(_m, "Eval", template)
+	ret0, _ := ret[0].(map[string]interface{})
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// Eval indicates an expected call of Eval
+func (_mr *MockvalClientMockRecorder) Eval(arg0 interface{}) *gomock.Call {
+	return _mr.mock.ctrl.RecordCallWithMethodType(_mr.mock, "Eval", reflect.TypeOf((*MockvalClient)(nil).Eval), arg0)
+}