feat: add stack.watch attribute (#448)

* feat: add stack.watch attribute

* chore: add tests

* remove log

* add test for watch file outside project

* make sure other not changed files dont change the result

* style

cmd/terramate/e2etests/list_watch_test.go

@@ -0,0 +1,155 @@
+// Copyright 2022 Mineiros GmbH
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package e2etest
+
+import (
+	"testing"
+
+	"github.com/mineiros-io/terramate/stack"
+	"github.com/mineiros-io/terramate/test/sandbox"
+)
+
+func TestListWatchChangedFile(t *testing.T) {
+	s := sandbox.New(t)
+
+	extDir := s.RootEntry().CreateDir("external")
+	extFile := extDir.CreateFile("file.txt", "anything")
+	extDir.CreateFile("not-changed.txt", "anything")
+
+	s.BuildTree([]string{
+		`s:stack:watch=["/external/file.txt", "/external/not-changed.txt"]`,
+	})
+
+	stack := s.LoadStack("stack")
+
+	cli := newCLI(t, s.RootDir())
+
+	git := s.Git()
+	git.CommitAll("all")
+	git.Push("main")
+	git.CheckoutNew("change-the-external")
+
+	extFile.Write("changed")
+	git.CommitAll("external file changed")
+
+	want := runExpected{
+		Stdout: stack.RelPath() + "\n",
+	}
+	assertRunResult(t, cli.listChangedStacks(), want)
+}
+
+func TestListWatchRelativeChangedFile(t *testing.T) {
+	s := sandbox.New(t)
+
+	extDir := s.RootEntry().CreateDir("external")
+	extFile := extDir.CreateFile("file.txt", "anything")
+
+	s.BuildTree([]string{
+		`s:stack:watch=["../external/file.txt"]`,
+	})
+
+	stack := s.LoadStack("stack")
+
+	cli := newCLI(t, s.RootDir())
+
+	git := s.Git()
+	git.CommitAll("all")
+	git.Push("main")
+	git.CheckoutNew("change-the-external")
+
+	extFile.Write("changed")
+	git.CommitAll("external file changed")
+
+	want := runExpected{
+		Stdout: stack.RelPath() + "\n",
+	}
+	assertRunResult(t, cli.listChangedStacks(), want)
+}
+
+func TestListWatchFileOutsideProject(t *testing.T) {
+	s := sandbox.New(t)
+
+	extDir := s.RootEntry().CreateDir("external")
+	extFile := extDir.CreateFile("file.txt", "anything")
+
+	s.BuildTree([]string{
+		`s:stack:watch=["../../this-stack-must-never-be-visible/terramate.tm.hcl"]`,
+	})
+
+	s.LoadStack("stack")
+
+	cli := newCLI(t, s.RootDir())
+
+	git := s.Git()
+	git.CommitAll("all")
+	git.Push("main")
+	git.CheckoutNew("change-the-external")
+
+	extFile.Write("changed")
+	git.CommitAll("external file changed")
+
+	want := runExpected{
+		Status:      1,
+		StderrRegex: string(stack.ErrInvalidWatch),
+	}
+	assertRunResult(t, cli.listChangedStacks(), want)
+}
+
+func TestListWatchNonExistentFile(t *testing.T) {
+	s := sandbox.New(t)
+
+	s.BuildTree([]string{
+		`s:stack:watch=["/external/non-existent.txt"]`,
+	})
+
+	cli := newCLI(t, s.RootDir())
+
+	git := s.Git()
+	git.CommitAll("all")
+	git.Push("main")
+	git.CheckoutNew("change-the-external")
+
+	s.RootEntry().CreateFile("test.txt", "anything")
+	git.CommitAll("any change")
+
+	assertRun(t, cli.listChangedStacks())
+}
+
+func TestListWatchDirectoryFails(t *testing.T) {
+	s := sandbox.New(t)
+
+	extDir := s.RootEntry().CreateDir("external")
+	extFile := extDir.CreateFile("file.txt", "anything")
+
+	s.BuildTree([]string{
+		`s:stack:watch=["/external"]`,
+	})
+
+	cli := newCLI(t, s.RootDir())
+
+	git := s.Git()
+	git.CommitAll("all")
+	git.Push("main")
+	git.CheckoutNew("change-the-external")
+
+	extFile.Write("changed")
+	git.CommitAll("external file changed")
+
+	want := runExpected{
+		Status:      1,
+		StderrRegex: string(stack.ErrInvalidWatch),
+	}
+	assertRunResult(t, cli.listChangedStacks(), want)
+}

hcl/hcl.go

@@ -107,6 +107,9 @@ type Stack struct {
 	// Wants is a list of non-duplicated stack entries that must be selected
 	// whenever the current stack is selected.
 	Wants []string
+
+	// Watch is a list of files to be watched for changes.
+	Watch []string
 }
 
 // GenHCLBlock represents a parsed generate_hcl block.
@@ -973,6 +976,9 @@ func parseStack(stack *Stack, stackblock *ast.Block) error {
 		case "wants":
 			errs.Append(assignSet(attr.Name, &stack.Wants, attrVal))
 
+		case "watch":
+			errs.Append(assignSet(attr.Name, &stack.Watch, attrVal))
+
 		case "description":
 			logger.Trace().Msg("parsing stack description.")
 			if attrVal.Type() != cty.String {

hcl/hcl_test.go

@@ -596,6 +596,7 @@ func TestHCLParserTerramateBlocksMerging(t *testing.T) {
 							after = ["after"]
 							before = ["before"]
 							wants = ["wants"]
+							watch = ["watch"]
 						}
 					`,
 				},
@@ -616,6 +617,7 @@ func TestHCLParserTerramateBlocksMerging(t *testing.T) {
 						After:       []string{"after"},
 						Before:      []string{"before"},
 						Wants:       []string{"wants"},
+						Watch:       []string{"watch"},
 					},
 				},
 			},

hcl/printer.go

@@ -78,6 +78,14 @@ func PrintConfig(w io.Writer, cfg Config) error {
 		stackBlock := rootBody.AppendNewBlock("stack", nil)
 		stackBody := stackBlock.Body()
 
+		if stack.Name != "" {
+			stackBody.SetAttributeValue("name", cty.StringVal(stack.Name))
+		}
+
+		if stack.Description != "" {
+			stackBody.SetAttributeValue("description", cty.StringVal(stack.Description))
+		}
+
 		if len(stack.After) > 0 {
 			stackBody.SetAttributeValue("after", cty.SetVal(listToValue(stack.After)))
 		}
@@ -90,12 +98,8 @@ func PrintConfig(w io.Writer, cfg Config) error {
 			stackBody.SetAttributeValue("wants", cty.SetVal(listToValue(stack.Wants)))
 		}
 
-		if stack.Name != "" {
-			stackBody.SetAttributeValue("name", cty.StringVal(stack.Name))
-		}
-
-		if stack.Description != "" {
-			stackBody.SetAttributeValue("description", cty.StringVal(stack.Description))
+		if len(stack.Watch) > 0 {
+			stackBody.SetAttributeValue("watch", cty.SetVal(listToValue(stack.Watch)))
 		}
 
 		if id, ok := stack.ID.Value(); ok {

manager.go

@@ -148,7 +148,7 @@ func (m *Manager) ListChanged() (*StacksReport, error) {
 
 	logger.Debug().Msg("List changed files.")
 
-	files, err := listChangedFiles(m.root, m.gitBaseRef)
+	changedFiles, err := listChangedFiles(m.root, m.gitBaseRef)
 	if err != nil {
 		return nil, errors.E(errListChanged, err)
 	}
@@ -157,7 +157,7 @@ func (m *Manager) ListChanged() (*StacksReport, error) {
 
 	logger.Trace().
 		Msg("Range over files.")
-	for _, path := range files {
+	for _, path := range changedFiles {
 		if strings.HasPrefix(path, ".") {
 			continue
 		}
@@ -207,12 +207,34 @@ func (m *Manager) ListChanged() (*StacksReport, error) {
 
 	logger.Trace().Msg("Range over all stacks.")
 
+rangeStacks:
 	for _, stackEntry := range allstacks {
 		stack := stackEntry.Stack
 		if _, ok := stackSet[stack.Path()]; ok {
 			continue
 		}
 
+		logger.Debug().
+			Stringer("stack", stack).
+			Msg("Check for changed watch files.")
+
+		if changed, ok := hasChangedWatchedFiles(stack, changedFiles); ok {
+			logger.Debug().
+				Stringer("stack", stack).
+				Str("watchfile", changed).
+				Msg("changed.")
+
+			stack.SetChanged(true)
+			stackSet[stack.Path()] = Entry{
+				Stack: stack,
+				Reason: fmt.Sprintf(
+					"stack changed because watched file %q changed",
+					changed,
+				),
+			}
+			continue rangeStacks
+		}
+
 		logger.Debug().
 			Stringer("stack", stack).
 			Msg("Apply function to stack.")
@@ -550,6 +572,17 @@ func listChangedFiles(dir string, gitBaseRef string) ([]string, error) {
 	return g.DiffNames(baseRef, headRef)
 }
 
+func hasChangedWatchedFiles(stack stack.S, changedFiles []string) (string, bool) {
+	for _, watchFile := range stack.Watch() {
+		for _, file := range changedFiles {
+			if file == watchFile[1:] { // project paths
+				return watchFile, true
+			}
+		}
+	}
+	return "", false
+}
+
 func checkRepoIsClean(g *git.Git) (RepoChecks, error) {
 	logger := log.With().
 		Str("action", "checkRepoIsClean()").