Skip cloning PR repository in case of no projects were changed

cmd/server.go

@@ -81,6 +81,7 @@ const (
 	SilenceAllowlistErrorsFlag = "silence-allowlist-errors"
 	// SilenceWhitelistErrorsFlag is deprecated for SilenceAllowlistErrorsFlag.
 	SilenceWhitelistErrorsFlag = "silence-whitelist-errors"
+	SkipCloneNoChanges         = "skip-clone-no-changes"
 	SlackTokenFlag             = "slack-token"
 	SSLCertFileFlag            = "ssl-cert-file"
 	SSLKeyFileFlag             = "ssl-key-file"
@@ -319,6 +320,10 @@ var boolFlags = map[string]boolFlag{
 			" This writes secrets to disk and should only be enabled in a secure environment.",
 		defaultValue: false,
 	},
+	SkipCloneNoChanges: {
+		description:  "Skips cloning the PR repo if there are no projects were changed in the PR.",
+		defaultValue: false,
+	},
 }
 var intFlags = map[string]intFlag{
 	PortFlag: {

cmd/server_test.go

@@ -86,6 +86,7 @@ var testFlags = map[string]interface{}{
 	SilenceForkPRErrorsFlag:    true,
 	SilenceAllowlistErrorsFlag: true,
 	SilenceVCSStatusNoPlans:    true,
+	SkipCloneNoChanges:         true,
 	SlackTokenFlag:             "slack-token",
 	SSLCertFileFlag:            "cert-file",
 	SSLKeyFileFlag:             "key-file",

server/events/project_command_builder.go

@@ -53,14 +53,15 @@ type ProjectCommandBuilder interface {
 // This class combines the data from the comment and any atlantis.yaml file or
 // Atlantis server config and then generates a set of contexts.
 type DefaultProjectCommandBuilder struct {
-	ParserValidator   *yaml.ParserValidator
-	ProjectFinder     ProjectFinder
-	VCSClient         vcs.Client
-	WorkingDir        WorkingDir
-	WorkingDirLocker  WorkingDirLocker
-	GlobalCfg         valid.GlobalCfg
-	PendingPlanFinder *DefaultPendingPlanFinder
-	CommentBuilder    CommentBuilder
+	ParserValidator    *yaml.ParserValidator
+	ProjectFinder      ProjectFinder
+	VCSClient          vcs.Client
+	WorkingDir         WorkingDir
+	WorkingDirLocker   WorkingDirLocker
+	GlobalCfg          valid.GlobalCfg
+	PendingPlanFinder  *DefaultPendingPlanFinder
+	CommentBuilder     CommentBuilder
+	SkipCloneNoChanges bool
 }
 
 // See ProjectCommandBuilder.BuildAutoplanCommands.
@@ -101,8 +102,43 @@ func (p *DefaultProjectCommandBuilder) BuildApplyCommands(ctx *CommandContext, c
 // buildPlanAllCommands builds plan contexts for all projects we determine were
 // modified in this ctx.
 func (p *DefaultProjectCommandBuilder) buildPlanAllCommands(ctx *CommandContext, commentFlags []string, verbose bool) ([]models.ProjectCommandContext, error) {
+	// We'll need the list of modified files.
+	modifiedFiles, err := p.VCSClient.GetModifiedFiles(ctx.BaseRepo, ctx.Pull)
+	if err != nil {
+		return nil, err
+	}
+	ctx.Log.Debug("%d files were modified in this pull request", len(modifiedFiles))
+
+	if p.SkipCloneNoChanges && p.VCSClient.SupportsSingleFileDownload(ctx.BaseRepo) {
+		hasRepoCfg, repoCfgData, err := p.VCSClient.DownloadRepoConfigFile(ctx.Pull)
+		if err != nil {
+			return nil, errors.Wrapf(err, "downloading %s", yaml.AtlantisYAMLFilename)
+		}
+
+		if hasRepoCfg {
+			repoCfg, err := p.ParserValidator.ParseRepoCfgData(repoCfgData, p.GlobalCfg, ctx.BaseRepo.ID())
+			if err != nil {
+				return nil, errors.Wrapf(err, "parsing %s", yaml.AtlantisYAMLFilename)
+			}
+			ctx.Log.Info("successfully parsed remote %s file", yaml.AtlantisYAMLFilename)
+			matchingProjects, err := p.ProjectFinder.DetermineProjectsViaConfig(ctx.Log, modifiedFiles, repoCfg, "")
+			if err != nil {
+				return nil, err
+			}
+			ctx.Log.Info("%d projects are changed on MR %q based on their when_modified config", len(matchingProjects), ctx.Pull.Num)
+			if len(matchingProjects) == 0 {
+				ctx.Log.Info("skipping repo clone since no project was modified")
+				return []models.ProjectCommandContext{}, nil
+			}
+			// NOTE: We discard this work here and end up doing it again after
+			// cloning to ensure all the return values are set properly with
+			// the actual clone directory.
+		}
+	}
+
 	// Need to lock the workspace we're about to clone to.
 	workspace := DefaultWorkspace
+
 	unlockFn, err := p.WorkingDirLocker.TryLock(ctx.BaseRepo.FullName, ctx.Pull.Num, workspace)
 	if err != nil {
 		ctx.Log.Warn("workspace was locked")
@@ -111,18 +147,10 @@ func (p *DefaultProjectCommandBuilder) buildPlanAllCommands(ctx *CommandContext,
 	ctx.Log.Debug("got workspace lock")
 	defer unlockFn()
 
-	// We'll need the list of modified files.
-	modifiedFiles, err := p.VCSClient.GetModifiedFiles(ctx.BaseRepo, ctx.Pull)
-	if err != nil {
-		return nil, err
-	}
-	ctx.Log.Debug("%d files were modified in this pull request", len(modifiedFiles))
-
 	repoDir, _, err := p.WorkingDir.Clone(ctx.Log, ctx.BaseRepo, ctx.HeadRepo, ctx.Pull, workspace)
 	if err != nil {
 		return nil, err
 	}
-
 	// Parse config file if it exists.
 	hasRepoCfg, err := p.ParserValidator.HasRepoCfg(repoDir)
 	if err != nil {

server/events/project_command_builder_internal_test.go

@@ -563,14 +563,15 @@ projects:
 			}
 
 			builder := &DefaultProjectCommandBuilder{
-				WorkingDirLocker:  NewDefaultWorkingDirLocker(),
-				WorkingDir:        workingDir,
-				ParserValidator:   parser,
-				VCSClient:         vcsClient,
-				ProjectFinder:     &DefaultProjectFinder{},
-				PendingPlanFinder: &DefaultPendingPlanFinder{},
-				CommentBuilder:    &CommentParser{},
-				GlobalCfg:         globalCfg,
+				WorkingDirLocker:   NewDefaultWorkingDirLocker(),
+				WorkingDir:         workingDir,
+				ParserValidator:    parser,
+				VCSClient:          vcsClient,
+				ProjectFinder:      &DefaultProjectFinder{},
+				PendingPlanFinder:  &DefaultPendingPlanFinder{},
+				CommentBuilder:     &CommentParser{},
+				GlobalCfg:          globalCfg,
+				SkipCloneNoChanges: false,
 			}
 
 			// We run a test for each type of command.

server/events/project_command_builder_test.go

@@ -135,14 +135,15 @@ projects:
 			}
 
 			builder := &events.DefaultProjectCommandBuilder{
-				WorkingDirLocker:  events.NewDefaultWorkingDirLocker(),
-				WorkingDir:        workingDir,
-				ParserValidator:   &yaml.ParserValidator{},
-				VCSClient:         vcsClient,
-				ProjectFinder:     &events.DefaultProjectFinder{},
-				PendingPlanFinder: &events.DefaultPendingPlanFinder{},
-				CommentBuilder:    &events.CommentParser{},
-				GlobalCfg:         valid.NewGlobalCfg(false, false, false),
+				WorkingDirLocker:   events.NewDefaultWorkingDirLocker(),
+				WorkingDir:         workingDir,
+				ParserValidator:    &yaml.ParserValidator{},
+				VCSClient:          vcsClient,
+				ProjectFinder:      &events.DefaultProjectFinder{},
+				PendingPlanFinder:  &events.DefaultPendingPlanFinder{},
+				CommentBuilder:     &events.CommentParser{},
+				GlobalCfg:          valid.NewGlobalCfg(false, false, false),
+				SkipCloneNoChanges: false,
 			}
 
 			ctxs, err := builder.BuildAutoplanCommands(&events.CommandContext{
@@ -358,13 +359,14 @@ projects:
 				}
 
 				builder := &events.DefaultProjectCommandBuilder{
-					WorkingDirLocker: events.NewDefaultWorkingDirLocker(),
-					WorkingDir:       workingDir,
-					ParserValidator:  &yaml.ParserValidator{},
-					VCSClient:        vcsClient,
-					ProjectFinder:    &events.DefaultProjectFinder{},
-					CommentBuilder:   &events.CommentParser{},
-					GlobalCfg:        valid.NewGlobalCfg(true, false, false),
+					WorkingDirLocker:   events.NewDefaultWorkingDirLocker(),
+					WorkingDir:         workingDir,
+					ParserValidator:    &yaml.ParserValidator{},
+					VCSClient:          vcsClient,
+					ProjectFinder:      &events.DefaultProjectFinder{},
+					CommentBuilder:     &events.CommentParser{},
+					GlobalCfg:          valid.NewGlobalCfg(true, false, false),
+					SkipCloneNoChanges: false,
 				}
 
 				var actCtxs []models.ProjectCommandContext
@@ -491,13 +493,14 @@ projects:
 			}
 
 			builder := &events.DefaultProjectCommandBuilder{
-				WorkingDirLocker: events.NewDefaultWorkingDirLocker(),
-				WorkingDir:       workingDir,
-				ParserValidator:  &yaml.ParserValidator{},
-				VCSClient:        vcsClient,
-				ProjectFinder:    &events.DefaultProjectFinder{},
-				CommentBuilder:   &events.CommentParser{},
-				GlobalCfg:        valid.NewGlobalCfg(true, false, false),
+				WorkingDirLocker:   events.NewDefaultWorkingDirLocker(),
+				WorkingDir:         workingDir,
+				ParserValidator:    &yaml.ParserValidator{},
+				VCSClient:          vcsClient,
+				ProjectFinder:      &events.DefaultProjectFinder{},
+				CommentBuilder:     &events.CommentParser{},
+				GlobalCfg:          valid.NewGlobalCfg(true, false, false),
+				SkipCloneNoChanges: false,
 			}
 
 			ctxs, err := builder.BuildPlanCommands(
@@ -562,14 +565,15 @@ func TestDefaultProjectCommandBuilder_BuildMultiApply(t *testing.T) {
 		ThenReturn(tmpDir, nil)
 
 	builder := &events.DefaultProjectCommandBuilder{
-		WorkingDirLocker:  events.NewDefaultWorkingDirLocker(),
-		WorkingDir:        workingDir,
-		ParserValidator:   &yaml.ParserValidator{},
-		VCSClient:         nil,
-		ProjectFinder:     &events.DefaultProjectFinder{},
-		PendingPlanFinder: &events.DefaultPendingPlanFinder{},
-		CommentBuilder:    &events.CommentParser{},
-		GlobalCfg:         valid.NewGlobalCfg(false, false, false),
+		WorkingDirLocker:   events.NewDefaultWorkingDirLocker(),
+		WorkingDir:         workingDir,
+		ParserValidator:    &yaml.ParserValidator{},
+		VCSClient:          nil,
+		ProjectFinder:      &events.DefaultProjectFinder{},
+		PendingPlanFinder:  &events.DefaultPendingPlanFinder{},
+		CommentBuilder:     &events.CommentParser{},
+		GlobalCfg:          valid.NewGlobalCfg(false, false, false),
+		SkipCloneNoChanges: false,
 	}
 
 	ctxs, err := builder.BuildApplyCommands(
@@ -630,13 +634,14 @@ projects:
 		AnyString())).ThenReturn(repoDir, nil)
 
 	builder := &events.DefaultProjectCommandBuilder{
-		WorkingDirLocker: events.NewDefaultWorkingDirLocker(),
-		WorkingDir:       workingDir,
-		ParserValidator:  &yaml.ParserValidator{},
-		VCSClient:        nil,
-		ProjectFinder:    &events.DefaultProjectFinder{},
-		CommentBuilder:   &events.CommentParser{},
-		GlobalCfg:        valid.NewGlobalCfg(true, false, false),
+		WorkingDirLocker:   events.NewDefaultWorkingDirLocker(),
+		WorkingDir:         workingDir,
+		ParserValidator:    &yaml.ParserValidator{},
+		VCSClient:          nil,
+		ProjectFinder:      &events.DefaultProjectFinder{},
+		CommentBuilder:     &events.CommentParser{},
+		GlobalCfg:          valid.NewGlobalCfg(true, false, false),
+		SkipCloneNoChanges: false,
 	}
 
 	ctx := &events.CommandContext{
@@ -692,13 +697,14 @@ func TestDefaultProjectCommandBuilder_EscapeArgs(t *testing.T) {
 			When(vcsClient.GetModifiedFiles(matchers.AnyModelsRepo(), matchers.AnyModelsPullRequest())).ThenReturn([]string{"main.tf"}, nil)
 
 			builder := &events.DefaultProjectCommandBuilder{
-				WorkingDirLocker: events.NewDefaultWorkingDirLocker(),
-				WorkingDir:       workingDir,
-				ParserValidator:  &yaml.ParserValidator{},
-				VCSClient:        vcsClient,
-				ProjectFinder:    &events.DefaultProjectFinder{},
-				CommentBuilder:   &events.CommentParser{},
-				GlobalCfg:        valid.NewGlobalCfg(true, false, false),
+				WorkingDirLocker:   events.NewDefaultWorkingDirLocker(),
+				WorkingDir:         workingDir,
+				ParserValidator:    &yaml.ParserValidator{},
+				VCSClient:          vcsClient,
+				ProjectFinder:      &events.DefaultProjectFinder{},
+				CommentBuilder:     &events.CommentParser{},
+				GlobalCfg:          valid.NewGlobalCfg(true, false, false),
+				SkipCloneNoChanges: false,
 			}
 
 			var actCtxs []models.ProjectCommandContext
@@ -856,13 +862,14 @@ projects:
 				AnyString())).ThenReturn(tmpDir, nil)
 
 			builder := &events.DefaultProjectCommandBuilder{
-				WorkingDirLocker: events.NewDefaultWorkingDirLocker(),
-				WorkingDir:       workingDir,
-				VCSClient:        vcsClient,
-				ParserValidator:  &yaml.ParserValidator{},
-				ProjectFinder:    &events.DefaultProjectFinder{},
-				CommentBuilder:   &events.CommentParser{},
-				GlobalCfg:        valid.NewGlobalCfg(true, false, false),
+				WorkingDirLocker:   events.NewDefaultWorkingDirLocker(),
+				WorkingDir:         workingDir,
+				VCSClient:          vcsClient,
+				ParserValidator:    &yaml.ParserValidator{},
+				ProjectFinder:      &events.DefaultProjectFinder{},
+				CommentBuilder:     &events.CommentParser{},
+				GlobalCfg:          valid.NewGlobalCfg(true, false, false),
+				SkipCloneNoChanges: false,
 			}
 
 			actCtxs, err := builder.BuildPlanCommands(
@@ -887,3 +894,43 @@ projects:
 		})
 	}
 }
+
+// Test that we don't clone the repo if there were no changes based on the atlantis.yaml file.
+func TestDefaultProjectCommandBuilder_SkipCloneNoChanges(t *testing.T) {
+	atlantisYAML := `
+version: 3
+projects:
+- dir: dir1`
+
+	RegisterMockTestingT(t)
+	vcsClient := vcsmocks.NewMockClient()
+	When(vcsClient.GetModifiedFiles(matchers.AnyModelsRepo(), matchers.AnyModelsPullRequest())).ThenReturn([]string{"main.tf"}, nil)
+	When(vcsClient.SupportsSingleFileDownload(matchers.AnyModelsRepo())).ThenReturn(true)
+	When(vcsClient.DownloadRepoConfigFile(matchers.AnyModelsPullRequest())).ThenReturn(true, []byte(atlantisYAML), nil)
+	workingDir := mocks.NewMockWorkingDir()
+
+	builder := &events.DefaultProjectCommandBuilder{
+		WorkingDirLocker:   events.NewDefaultWorkingDirLocker(),
+		WorkingDir:         workingDir,
+		ParserValidator:    &yaml.ParserValidator{},
+		VCSClient:          vcsClient,
+		ProjectFinder:      &events.DefaultProjectFinder{},
+		CommentBuilder:     &events.CommentParser{},
+		GlobalCfg:          valid.NewGlobalCfg(true, false, false),
+		SkipCloneNoChanges: true,
+	}
+
+	var actCtxs []models.ProjectCommandContext
+	var err error
+	actCtxs, err = builder.BuildAutoplanCommands(&events.CommandContext{
+		BaseRepo:      models.Repo{},
+		HeadRepo:      models.Repo{},
+		Pull:          models.PullRequest{},
+		User:          models.User{},
+		Log:           nil,
+		PullMergeable: true,
+	})
+	Ok(t, err)
+	Equals(t, 0, len(actCtxs))
+	workingDir.VerifyWasCalled(Never()).Clone(matchers.AnyPtrToLoggingSimpleLogger(), matchers.AnyModelsRepo(), matchers.AnyModelsRepo(), matchers.AnyModelsPullRequest(), AnyString())
+}