Merge pull request #1158 from runatlantis/skip-clone

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/matchers/models_pullrequest.go

@@ -3,6 +3,7 @@ package matchers
 
 import (
 	"reflect"
+
 	"github.com/petergtz/pegomock"
 	models "github.com/runatlantis/atlantis/server/events/models"
 )

server/events/matchers/models_repo.go

@@ -3,6 +3,7 @@ package matchers
 
 import (
 	"reflect"
+
 	"github.com/petergtz/pegomock"
 	models "github.com/runatlantis/atlantis/server/events/models"
 )

server/events/matchers/ptr_to_logging_simplelogger.go

@@ -3,6 +3,7 @@ package matchers
 
 import (
 	"reflect"
+
 	"github.com/petergtz/pegomock"
 	logging "github.com/runatlantis/atlantis/server/logging"
 )

server/events/mock_workingdir_test.go

@@ -4,11 +4,12 @@
 package events
 
 import (
+	"reflect"
+	"time"
+
 	pegomock "github.com/petergtz/pegomock"
 	models "github.com/runatlantis/atlantis/server/events/models"
 	logging "github.com/runatlantis/atlantis/server/logging"
-	"reflect"
-	"time"
 )
 
 type MockWorkingDir struct {

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())
+}

server/events/project_finder.go

@@ -120,11 +120,22 @@ func (p *DefaultProjectFinder) DetermineProjectsViaConfig(log *logging.SimpleLog
 			}
 			if match {
 				log.Debug("file %q matched pattern", file)
-				_, err := os.Stat(filepath.Join(absRepoDir, project.Dir))
-				if err == nil {
-					projects = append(projects, project)
+				// If we're checking using an atlantis.yaml file we downloaded
+				// directly from the repo (when doing a no-clone check) then
+				// absRepoDir will be empty. Since we didn't clone the repo
+				// yet we can't do this check. If there was a file modified
+				// in a deleted directory then when we finally do clone the repo
+				// we'll call this function again and then we'll detect the
+				// directory was deleted.
+				if absRepoDir != "" {
+					_, err := os.Stat(filepath.Join(absRepoDir, project.Dir))
+					if err == nil {
+						projects = append(projects, project)
+					} else {
+						log.Debug("project at dir %q not included because dir does not exist", project.Dir)
+					}
 				} else {
-					log.Debug("project at dir %q not included because dir does not exist", project.Dir)
+					projects = append(projects, project)
 				}
 				break
 			}

server/events/vcs/azuredevops_client.go

@@ -364,3 +364,11 @@ func SplitAzureDevopsRepoFullName(repoFullName string) (owner string, project st
 	}
 	return repoFullName[:lastSlashIdx], "", repoFullName[lastSlashIdx+1:]
 }
+
+func (g *AzureDevopsClient) SupportsSingleFileDownload(repo models.Repo) bool {
+	return false
+}
+
+func (g *AzureDevopsClient) DownloadRepoConfigFile(pull models.PullRequest) (bool, []byte, error) {
+	return false, []byte{}, fmt.Errorf("Not Implemented")
+}

server/events/vcs/bitbucketcloud/client.go

@@ -243,3 +243,14 @@ func (b *Client) makeRequest(method string, path string, reqBody io.Reader) ([]b
 	}
 	return respBody, nil
 }
+
+func (b *Client) SupportsSingleFileDownload(models.Repo) bool {
+	return false
+}
+
+// DownloadRepoConfigFile return `atlantis.yaml` content from VCS (which support fetch a single file from repository)
+// The first return value indicate that repo contain atlantis.yaml or not
+// if BaseRepo had one repo config file, its content will placed on the second return value
+func (b *Client) DownloadRepoConfigFile(pull models.PullRequest) (bool, []byte, error) {
+	return false, []byte{}, fmt.Errorf("Not Implemented")
+}

server/events/vcs/bitbucketserver/client.go

@@ -311,3 +311,14 @@ func (b *Client) makeRequest(method string, path string, reqBody io.Reader) ([]b
 	}
 	return respBody, nil
 }
+
+func (b *Client) SupportsSingleFileDownload(repo models.Repo) bool {
+	return false
+}
+
+// DownloadRepoConfigFile return `atlantis.yaml` content from VCS (which support fetch a single file from repository)
+// The first return value indicate that repo contain atlantis.yaml or not
+// if BaseRepo had one repo config file, its content will placed on the second return value
+func (b *Client) DownloadRepoConfigFile(pull models.PullRequest) (bool, []byte, error) {
+	return false, []byte{}, fmt.Errorf("not implemented")
+}

server/events/vcs/client.go

@@ -38,4 +38,10 @@ type Client interface {
 	UpdateStatus(repo models.Repo, pull models.PullRequest, state models.CommitStatus, src string, description string, url string) error
 	MergePull(pull models.PullRequest) error
 	MarkdownPullLink(pull models.PullRequest) (string, error)
+
+	// DownloadRepoConfigFile return `atlantis.yaml` content from VCS (which support fetch a single file from repository)
+	// The first return value indicate that repo contain atlantis.yaml or not
+	// if BaseRepo had one repo config file, its content will placed on the second return value
+	DownloadRepoConfigFile(pull models.PullRequest) (bool, []byte, error)
+	SupportsSingleFileDownload(repo models.Repo) bool
 }

server/events/vcs/github_client.go

@@ -15,17 +15,19 @@ package vcs
 
 import (
 	"context"
+	"encoding/base64"
 	"fmt"
+	"net/http"
 	"strings"
 	"time"
 
-	"github.com/runatlantis/atlantis/server/events/models"
-	"github.com/runatlantis/atlantis/server/events/vcs/common"
-	"github.com/runatlantis/atlantis/server/logging"
-
 	"github.com/Laisky/graphql"
 	"github.com/google/go-github/v31/github"
 	"github.com/pkg/errors"
+	"github.com/runatlantis/atlantis/server/events/models"
+	"github.com/runatlantis/atlantis/server/events/vcs/common"
+	"github.com/runatlantis/atlantis/server/events/yaml"
+	"github.com/runatlantis/atlantis/server/logging"
 	"github.com/shurcooL/githubv4"
 )
 
@@ -384,3 +386,29 @@ func (g *GithubClient) ExchangeCode(code string) (*GithubAppTemporarySecrets, er
 
 	return data, err
 }
+
+// DownloadRepoConfigFile return `atlantis.yaml` content from VCS (which support fetch a single file from repository)
+// The first return value indicate that repo contain atlantis.yaml or not
+// if BaseRepo had one repo config file, its content will placed on the second return value
+func (g *GithubClient) DownloadRepoConfigFile(pull models.PullRequest) (bool, []byte, error) {
+	opt := github.RepositoryContentGetOptions{Ref: pull.HeadBranch}
+	fileContent, _, resp, err := g.client.Repositories.GetContents(g.ctx, pull.BaseRepo.Owner, pull.BaseRepo.Name, yaml.AtlantisYAMLFilename, &opt)
+
+	if resp.StatusCode == http.StatusNotFound {
+		return false, []byte{}, nil
+	}
+	if err != nil {
+		return true, []byte{}, err
+	}
+
+	decodedData, err := base64.StdEncoding.DecodeString(*fileContent.Content)
+	if err != nil {
+		return true, []byte{}, err
+	}
+
+	return true, decodedData, nil
+}
+
+func (g *GithubClient) SupportsSingleFileDownload(repo models.Repo) bool {
+	return true
+}

server/events/vcs/gitlab_client.go

@@ -16,9 +16,12 @@ package vcs
 import (
 	"fmt"
 	"net"
+	"net/http"
 	"net/url"
 	"strings"
 
+	"github.com/runatlantis/atlantis/server/events/yaml"
+
 	"github.com/runatlantis/atlantis/server/events/vcs/common"
 
 	version "github.com/hashicorp/go-version"
@@ -269,3 +272,25 @@ func MustConstraint(constraint string) version.Constraints {
 	}
 	return c
 }
+
+// DownloadRepoConfigFile return `atlantis.yaml` content from VCS (which support fetch a single file from repository)
+// The first return value indicate that repo contain atlantis.yaml or not
+// if BaseRepo had one repo config file, its content will placed on the second return value
+func (g *GitlabClient) DownloadRepoConfigFile(pull models.PullRequest) (bool, []byte, error) {
+	opt := gitlab.GetRawFileOptions{Ref: gitlab.String(pull.HeadBranch)}
+
+	bytes, resp, err := g.Client.RepositoryFiles.GetRawFile(pull.BaseRepo.FullName, yaml.AtlantisYAMLFilename, &opt)
+	if resp.StatusCode == http.StatusNotFound {
+		return false, []byte{}, nil
+	}
+
+	if err != nil {
+		return true, []byte{}, err
+	}
+
+	return true, bytes, nil
+}
+
+func (g *GitlabClient) SupportsSingleFileDownload(repo models.Repo) bool {
+	return true
+}

server/events/vcs/mocks/matchers/slice_of_byte.go

@@ -0,0 +1,20 @@
+// Code generated by pegomock. DO NOT EDIT.
+package matchers
+
+import (
+	"reflect"
+	"github.com/petergtz/pegomock"
+	
+)
+
+func AnySliceOfByte() []byte {
+	pegomock.RegisterMatcher(pegomock.NewAnyMatcher(reflect.TypeOf((*([]byte))(nil)).Elem()))
+	var nullValue []byte
+	return nullValue
+}
+
+func EqSliceOfByte(value []byte) []byte {
+	pegomock.RegisterMatcher(&pegomock.EqMatcher{Value: value})
+	var nullValue []byte
+	return nullValue
+}

server/events/vcs/mocks/mock_client.go

@@ -161,6 +161,44 @@ func (mock *MockClient) MarkdownPullLink(pull models.PullRequest) (string, error
 	return ret0, ret1
 }
 
+func (mock *MockClient) DownloadRepoConfigFile(pull models.PullRequest) (bool, []byte, error) {
+	if mock == nil {
+		panic("mock must not be nil. Use myMock := NewMockClient().")
+	}
+	params := []pegomock.Param{pull}
+	result := pegomock.GetGenericMockFrom(mock).Invoke("DownloadRepoConfigFile", params, []reflect.Type{reflect.TypeOf((*bool)(nil)).Elem(), reflect.TypeOf((*[]byte)(nil)).Elem(), reflect.TypeOf((*error)(nil)).Elem()})
+	var ret0 bool
+	var ret1 []byte
+	var ret2 error
+	if len(result) != 0 {
+		if result[0] != nil {
+			ret0 = result[0].(bool)
+		}
+		if result[1] != nil {
+			ret1 = result[1].([]byte)
+		}
+		if result[2] != nil {
+			ret2 = result[2].(error)
+		}
+	}
+	return ret0, ret1, ret2
+}
+
+func (mock *MockClient) SupportsSingleFileDownload(repo models.Repo) bool {
+	if mock == nil {
+		panic("mock must not be nil. Use myMock := NewMockClient().")
+	}
+	params := []pegomock.Param{repo}
+	result := pegomock.GetGenericMockFrom(mock).Invoke("SupportsSingleFileDownload", params, []reflect.Type{reflect.TypeOf((*bool)(nil)).Elem()})
+	var ret0 bool
+	if len(result) != 0 {
+		if result[0] != nil {
+			ret0 = result[0].(bool)
+		}
+	}
+	return ret0
+}
+
 func (mock *MockClient) VerifyWasCalledOnce() *VerifierMockClient {
 	return &VerifierMockClient{
 		mock:                   mock,
@@ -461,3 +499,57 @@ func (c *MockClient_MarkdownPullLink_OngoingVerification) GetAllCapturedArgument
 	}
 	return
 }
+
+func (verifier *VerifierMockClient) DownloadRepoConfigFile(pull models.PullRequest) *MockClient_DownloadRepoConfigFile_OngoingVerification {
+	params := []pegomock.Param{pull}
+	methodInvocations := pegomock.GetGenericMockFrom(verifier.mock).Verify(verifier.inOrderContext, verifier.invocationCountMatcher, "DownloadRepoConfigFile", params, verifier.timeout)
+	return &MockClient_DownloadRepoConfigFile_OngoingVerification{mock: verifier.mock, methodInvocations: methodInvocations}
+}
+
+type MockClient_DownloadRepoConfigFile_OngoingVerification struct {
+	mock              *MockClient
+	methodInvocations []pegomock.MethodInvocation
+}
+
+func (c *MockClient_DownloadRepoConfigFile_OngoingVerification) GetCapturedArguments() models.PullRequest {
+	pull := c.GetAllCapturedArguments()
+	return pull[len(pull)-1]
+}
+
+func (c *MockClient_DownloadRepoConfigFile_OngoingVerification) GetAllCapturedArguments() (_param0 []models.PullRequest) {
+	params := pegomock.GetGenericMockFrom(c.mock).GetInvocationParams(c.methodInvocations)
+	if len(params) > 0 {
+		_param0 = make([]models.PullRequest, len(c.methodInvocations))
+		for u, param := range params[0] {
+			_param0[u] = param.(models.PullRequest)
+		}
+	}
+	return
+}
+
+func (verifier *VerifierMockClient) SupportsSingleFileDownload(repo models.Repo) *MockClient_SupportsSingleFileDownload_OngoingVerification {
+	params := []pegomock.Param{repo}
+	methodInvocations := pegomock.GetGenericMockFrom(verifier.mock).Verify(verifier.inOrderContext, verifier.invocationCountMatcher, "SupportsSingleFileDownload", params, verifier.timeout)
+	return &MockClient_SupportsSingleFileDownload_OngoingVerification{mock: verifier.mock, methodInvocations: methodInvocations}
+}
+
+type MockClient_SupportsSingleFileDownload_OngoingVerification struct {
+	mock              *MockClient
+	methodInvocations []pegomock.MethodInvocation
+}
+
+func (c *MockClient_SupportsSingleFileDownload_OngoingVerification) GetCapturedArguments() models.Repo {
+	repo := c.GetAllCapturedArguments()
+	return repo[len(repo)-1]
+}
+
+func (c *MockClient_SupportsSingleFileDownload_OngoingVerification) GetAllCapturedArguments() (_param0 []models.Repo) {
+	params := pegomock.GetGenericMockFrom(c.mock).GetInvocationParams(c.methodInvocations)
+	if len(params) > 0 {
+		_param0 = make([]models.Repo, len(c.methodInvocations))
+		for u, param := range params[0] {
+			_param0[u] = param.(models.Repo)
+		}
+	}
+	return
+}

server/events/vcs/not_configured_vcs_client.go

@@ -53,3 +53,11 @@ func (a *NotConfiguredVCSClient) MarkdownPullLink(pull models.PullRequest) (stri
 func (a *NotConfiguredVCSClient) err() error {
 	return fmt.Errorf("atlantis was not configured to support repos from %s", a.Host.String())
 }
+
+func (a *NotConfiguredVCSClient) SupportsSingleFileDownload(repo models.Repo) bool {
+	return false
+}
+
+func (a *NotConfiguredVCSClient) DownloadRepoConfigFile(pull models.PullRequest) (bool, []byte, error) {
+	return true, []byte{}, a.err()
+}

server/events/vcs/proxy.go

@@ -83,3 +83,11 @@ func (d *ClientProxy) MergePull(pull models.PullRequest) error {
 func (d *ClientProxy) MarkdownPullLink(pull models.PullRequest) (string, error) {
 	return d.clients[pull.BaseRepo.VCSHost.Type].MarkdownPullLink(pull)
 }
+
+func (d *ClientProxy) DownloadRepoConfigFile(pull models.PullRequest) (bool, []byte, error) {
+	return d.clients[pull.BaseRepo.VCSHost.Type].DownloadRepoConfigFile(pull)
+}
+
+func (d *ClientProxy) SupportsSingleFileDownload(repo models.Repo) bool {
+	return d.clients[repo.VCSHost.Type].SupportsSingleFileDownload(repo)
+}

server/events/yaml/parser_validator.go

@@ -56,9 +56,12 @@ func (p *ParserValidator) ParseRepoCfg(absRepoDir string, globalCfg valid.Global
 		// able to detect if it's a NotExist err.
 		return valid.RepoCfg{}, err
 	}
+	return p.ParseRepoCfgData(configData, globalCfg, repoID)
+}
 
+func (p *ParserValidator) ParseRepoCfgData(repoCfgData []byte, globalCfg valid.GlobalCfg, repoID string) (valid.RepoCfg, error) {
 	var rawConfig raw.RepoCfg
-	if err := yaml.UnmarshalStrict(configData, &rawConfig); err != nil {
+	if err := yaml.UnmarshalStrict(repoCfgData, &rawConfig); err != nil {
 		return valid.RepoCfg{}, err
 	}
 
@@ -83,7 +86,7 @@ func (p *ParserValidator) ParseRepoCfg(absRepoDir string, globalCfg valid.Global
 		}
 	}
 
-	err = globalCfg.ValidateRepoCfg(validConfig, repoID)
+	err := globalCfg.ValidateRepoCfg(validConfig, repoID)
 	return validConfig, err
 }
 

server/events_controller_e2e_test.go

@@ -476,14 +476,15 @@ func setupE2E(t *testing.T, repoDir string) (server.EventsController, *vcsmocks.
 		AllowForkPRs:             allowForkPRs,
 		AllowForkPRsFlag:         "allow-fork-prs",
 		ProjectCommandBuilder: &events.DefaultProjectCommandBuilder{
-			ParserValidator:   parser,
-			ProjectFinder:     &events.DefaultProjectFinder{},
-			VCSClient:         e2eVCSClient,
-			WorkingDir:        workingDir,
-			WorkingDirLocker:  locker,
-			PendingPlanFinder: &events.DefaultPendingPlanFinder{},
-			CommentBuilder:    commentParser,
-			GlobalCfg:         globalCfg,
+			ParserValidator:    parser,
+			ProjectFinder:      &events.DefaultProjectFinder{},
+			VCSClient:          e2eVCSClient,
+			WorkingDir:         workingDir,
+			WorkingDirLocker:   locker,
+			PendingPlanFinder:  &events.DefaultPendingPlanFinder{},
+			CommentBuilder:     commentParser,
+			GlobalCfg:          globalCfg,
+			SkipCloneNoChanges: false,
 		},
 		DB:                boltdb,
 		PendingPlanFinder: &events.DefaultPendingPlanFinder{},

server/server.go

@@ -370,14 +370,15 @@ func NewServer(userConfig UserConfig, config Config) (*Server, error) {
 		SilenceVCSStatusNoPlans:  userConfig.SilenceVCSStatusNoPlans,
 		DisableApplyAll:          userConfig.DisableApplyAll,
 		ProjectCommandBuilder: &events.DefaultProjectCommandBuilder{
-			ParserValidator:   validator,
-			ProjectFinder:     &events.DefaultProjectFinder{},
-			VCSClient:         vcsClient,
-			WorkingDir:        workingDir,
-			WorkingDirLocker:  workingDirLocker,
-			GlobalCfg:         globalCfg,
-			PendingPlanFinder: pendingPlanFinder,
-			CommentBuilder:    commentParser,
+			ParserValidator:    validator,
+			ProjectFinder:      &events.DefaultProjectFinder{},
+			VCSClient:          vcsClient,
+			WorkingDir:         workingDir,
+			WorkingDirLocker:   workingDirLocker,
+			GlobalCfg:          globalCfg,
+			PendingPlanFinder:  pendingPlanFinder,
+			CommentBuilder:     commentParser,
+			SkipCloneNoChanges: userConfig.SkipCloneNoChanges,
 		},
 		ProjectCommandRunner: &events.DefaultProjectCommandRunner{
 			Locker:           projectLocker,

server/user_config.go

@@ -58,6 +58,7 @@ type UserConfig struct {
 	SilenceAllowlistErrors  bool `mapstructure:"silence-allowlist-errors"`
 	// SilenceWhitelistErrors is deprecated in favour of SilenceAllowlistErrors
 	SilenceWhitelistErrors bool            `mapstructure:"silence-whitelist-errors"`
+	SkipCloneNoChanges     bool            `mapstructure:"skip-clone-no-changes"`
 	SlackToken             string          `mapstructure:"slack-token"`
 	SSLCertFile            string          `mapstructure:"ssl-cert-file"`
 	SSLKeyFile             string          `mapstructure:"ssl-key-file"`