feat: support skipping no changes

pkg/cli/app.go

@@ -72,6 +72,10 @@ func New(flags *LDFlags) *cli.App {
 					Name:  "patch",
 					Usage: "update an existing comment instead of creating a new comment. If there is no existing comment, a new comment is created.",
 				},
+				&cli.BoolFlag{
+					Name:  "skip-no-changes",
+					Usage: "If there is no change tfcmt updates a label but doesn't post a comment",
+				},
 			},
 		},
 		{

pkg/cli/var.go

@@ -62,6 +62,10 @@ func parseOpts(ctx *cli.Context, cfg *config.Config, envs []string) error {
 		cfg.Output = output
 	}
 
+	if ctx.IsSet("skip-no-changes") {
+		cfg.Terraform.Plan.WhenNoChanges.DisableComment = ctx.Bool("skip-no-changes")
+	}
+
 	vars := ctx.StringSlice("var")
 	vm := make(map[string]string, len(vars))
 	if err := parseVars(vars, envs, vm); err != nil {

pkg/config/config.go

@@ -74,9 +74,10 @@ type WhenDestroy struct {
 
 // WhenNoChanges is a configuration to add a label when the plan result contains no change
 type WhenNoChanges struct {
-	Label        string
-	Color        string `yaml:"label_color"`
-	DisableLabel bool   `yaml:"disable_label"`
+	Label          string
+	Color          string `yaml:"label_color"`
+	DisableLabel   bool   `yaml:"disable_label"`
+	DisableComment bool   `yaml:"disable_comment"`
 }
 
 // WhenPlanError is a configuration to notify the plan result returns an error

pkg/controller/controller.go

@@ -169,6 +169,7 @@ func (ctrl *Controller) getNotifier(ctx context.Context) (notifier.Notifier, err
 		EmbeddedVarNames:   ctrl.Config.EmbeddedVarNames,
 		Templates:          ctrl.Config.Templates,
 		Patch:              ctrl.Config.PlanPatch,
+		SkipNoChanges:      ctrl.Config.Terraform.Plan.WhenNoChanges.DisableComment,
 	})
 	if err != nil {
 		return nil, err

pkg/notifier/github/client.go

@@ -56,6 +56,7 @@ type Config struct {
 	Templates        map[string]string
 	UseRawOutput     bool
 	Patch            bool
+	SkipNoChanges    bool
 }
 
 // PullRequest represents GitHub Pull Request metadata

pkg/notifier/github/plan.go

@@ -11,71 +11,32 @@ import (
 // Plan posts comment optimized for notifications
 func (g *NotifyService) Plan(ctx context.Context, param *notifier.ParamExec) (int, error) { //nolint:cyclop
 	cfg := g.client.Config
-	parser := g.client.Config.Parser
-	template := g.client.Config.Template
-	var errMsgs []string
 
 	if cfg.PR.Number == 0 && cfg.PR.Revision != "" {
 		if prNumber, err := g.client.Commits.PRNumber(ctx, cfg.PR.Revision, PullRequestStateOpen); err == nil {
 			cfg.PR.Number = prNumber
 		}
 	}
 
-	result := parser.Parse(param.CombinedOutput)
+	result := g.client.Config.Parser.Parse(param.CombinedOutput)
 	result.ExitCode = param.ExitCode
-	if result.HasParseError {
-		template = g.client.Config.ParseErrorTemplate
-	} else {
-		if result.Error != nil {
-			return result.ExitCode, result.Error
-		}
-		if result.Result == "" {
-			return result.ExitCode, result.Error
-		}
+	if !result.HasParseError && (result.Error != nil || result.Result == "") {
+		return result.ExitCode, result.Error
 	}
 
+	var errMsgs []string
 	if cfg.PR.IsNumber() && cfg.ResultLabels.HasAnyLabelDefined() {
 		errMsgs = append(errMsgs, g.updateLabels(ctx, result)...)
 	}
 
-	template.SetValue(terraform.CommonTemplate{
-		Result:                 result.Result,
-		ChangedResult:          result.ChangedResult,
-		ChangeOutsideTerraform: result.OutsideTerraform,
-		Warning:                result.Warning,
-		HasDestroy:             result.HasDestroy,
-		Link:                   cfg.CI,
-		UseRawOutput:           cfg.UseRawOutput,
-		Vars:                   cfg.Vars,
-		Templates:              cfg.Templates,
-		Stdout:                 param.Stdout,
-		Stderr:                 param.Stderr,
-		CombinedOutput:         param.CombinedOutput,
-		ExitCode:               param.ExitCode,
-		ErrorMessages:          errMsgs,
-		CreatedResources:       result.CreatedResources,
-		UpdatedResources:       result.UpdatedResources,
-		DeletedResources:       result.DeletedResources,
-		ReplacedResources:      result.ReplacedResources,
-	})
-	body, err := template.Execute()
-	if err != nil {
-		return result.ExitCode, err
-	}
-
 	logE := logrus.WithFields(logrus.Fields{
 		"program": "tfcmt",
 	})
 
-	embeddedComment, err := getEmbeddedComment(cfg, param.CIName, true)
+	body, err := g.buildBody(logE, &result, param, errMsgs)
 	if err != nil {
 		return result.ExitCode, err
 	}
-	logE.WithFields(logrus.Fields{
-		"comment": embeddedComment,
-	}).Debug("embedded HTML comment")
-	// embed HTML tag to hide old comments
-	body += embeddedComment
 
 	if cfg.Patch && cfg.PR.Number != 0 {
 		logE.Debug("try patching")
@@ -105,6 +66,11 @@ func (g *NotifyService) Plan(ctx context.Context, param *notifier.ParamExec) (in
 		}
 	}
 
+	if result.HasNoChanges {
+		logE.Debug("skip posting a comment because there is no change")
+		return result.ExitCode, nil
+	}
+
 	logE.Debug("create a comment")
 	if err := g.client.Comment.Post(ctx, body, &PostOptions{
 		Number:   cfg.PR.Number,
@@ -114,3 +80,46 @@ func (g *NotifyService) Plan(ctx context.Context, param *notifier.ParamExec) (in
 	}
 	return result.ExitCode, nil
 }
+
+func (g *NotifyService) buildBody(logE *logrus.Entry, result *terraform.ParseResult, param *notifier.ParamExec, errMsgs []string) (string, error) {
+	template := g.client.Config.Template
+	if result.HasParseError {
+		template = g.client.Config.ParseErrorTemplate
+	}
+	cfg := g.client.Config
+	template.SetValue(terraform.CommonTemplate{
+		Result:                 result.Result,
+		ChangedResult:          result.ChangedResult,
+		ChangeOutsideTerraform: result.OutsideTerraform,
+		Warning:                result.Warning,
+		HasDestroy:             result.HasDestroy,
+		Link:                   cfg.CI,
+		UseRawOutput:           cfg.UseRawOutput,
+		Vars:                   cfg.Vars,
+		Templates:              cfg.Templates,
+		Stdout:                 param.Stdout,
+		Stderr:                 param.Stderr,
+		CombinedOutput:         param.CombinedOutput,
+		ExitCode:               param.ExitCode,
+		ErrorMessages:          errMsgs,
+		CreatedResources:       result.CreatedResources,
+		UpdatedResources:       result.UpdatedResources,
+		DeletedResources:       result.DeletedResources,
+		ReplacedResources:      result.ReplacedResources,
+	})
+	body, err := template.Execute()
+	if err != nil {
+		return "", err
+	}
+
+	embeddedComment, err := getEmbeddedComment(cfg, param.CIName, true)
+	if err != nil {
+		return "", err
+	}
+	logE.WithFields(logrus.Fields{
+		"comment": embeddedComment,
+	}).Debug("embedded HTML comment")
+	// embed HTML tag to hide old comments
+	body += embeddedComment
+	return body, nil
+}