[9.2](backport #6612) [OpAMP] Add TestOpAMPWithEDOTCollector E2E test (#6663)

* [OpAMP] Add `TestOpAMPWithEDOTCollector` E2E test (#6612)

* test(e2e): add EDOT Collector OpAMP E2E test

- Add TestEDOTOpAMP to verify that the EDOT Collector bundled inside the
  Elastic Agent package can connect to Fleet Server over OpAMP and enroll
  in .fleet-agents
- Extract shared agent download/extract helpers (downloadElasticAgent,
  extractAgentArchive) into agent_download.go, refactoring the duplicated
  code from AgentInstallSuite
- Fix TestOpAMP: pre-create the bin/ directory before running make
  otelcontribcol, which requires it to exist

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* e2e: add TestOpAMPWithEDOTCollector and refactor shared OpAMP setup

- Extract shared download/extract helpers into agent_download.go with
  caching (sha512 comparison), FileReplacer, ExtractFilter, and correct
  chmod after extraction
- Extract startFleetServerForOpAMP and writeOpAMPCollectorConfig helpers
  shared by both OpAMP tests
- Rename TestOpAMP → TestOpAMPWithUpstreamCollector
- Add TestOpAMPWithEDOTCollector: downloads elastic-agent package,
  runs elastic-agent otel subcommand, verifies EDOT Collector enrolls
  in Fleet Server over OpAMP

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* chore(e2e): clean up OpAMP test comments and simplify writeOpAMPCollectorConfig

Update inline comments, simplify writeOpAMPCollectorConfig to take a
single configFilePath parameter, and add newlines after Require()
statements for readability.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* chore(e2e): improve EDOT test readability

Elaborate on the processExited comment and move the Cleanup block below
the early-exit check so the flow reads top-to-bottom.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* chore(e2e): fix stale comments in EDOT test

Rename "immediate exit" to "early exit" for consistency and update
the Cleanup comment now that it is registered after the early-exit check.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor(e2e): extract standalone extractTar/extractZip into agent_download.go

Move archive extraction out of AgentInstallSuite into standalone
functions so both AgentInstallSuite and StandAloneSuite can reuse them.
AgentInstallSuite now overwrites the fleet-server binary after extraction
instead of during.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(e2e): remove implicit parent directory creation in extractTar/extractZip

Remove MkdirAll(filepath.Dir(path)) calls for regular files and symlinks
so that missing directory entries in archives surface as test failures
rather than being silently papered over (ref: PR #4985).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor(e2e): replace static instance UIDs with generated UUIDv7s

Use uuid.Must(uuid.NewV7()) instead of hardcoded UUIDs for OpAMP test
instance UIDs, as suggested in review.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
(cherry picked from commit 5ece964)

# Conflicts:
#	testing/e2e/stand_alone_test.go

* Fixing conflicts

---------

Co-authored-by: Shaunak Kashyap <ycombinator@gmail.com>

Author: mergify[bot]

testing/e2e/agent_download.go

@@ -7,10 +7,15 @@
 package e2e
 
 import (
+	"archive/tar"
+	"archive/zip"
+	"bytes"
+	"compress/gzip"
 	"context"
 	"crypto/sha512"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -190,6 +195,131 @@ func fetchRemoteSHA512(ctx context.Context, t *testing.T, client *http.Client, u
 	return strings.Fields(string(data))[0]
 }
 
+// extractedPaths holds paths to notable binaries found during archive extraction.
+type extractedPaths struct {
+	agentBinary       string // path to the elastic-agent binary
+	fleetServerBinary string // path to the fleet-server binary
+}
+
+// extractTar extracts a tar.gz archive from r into destDir, returning the
+// paths to notable binaries found during extraction.
+func extractTar(t *testing.T, r io.Reader, destDir string) extractedPaths {
+	t.Helper()
+	gs, err := gzip.NewReader(r)
+	if err != nil {
+		t.Fatalf("failed to create gzip reader: %v", err)
+	}
+
+	var paths extractedPaths
+	tarReader := tar.NewReader(gs)
+	for {
+		header, err := tarReader.Next()
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		if err != nil {
+			t.Fatalf("failed to read tar entry: %v", err)
+		}
+
+		path := filepath.Join(destDir, header.Name)
+		mode := header.FileInfo().Mode()
+		switch {
+		case mode.IsDir():
+			if err := os.MkdirAll(path, 0755); err != nil {
+				t.Fatalf("failed to create directory %s: %v", path, err)
+			}
+		case mode.IsRegular():
+			// Ensure parent directories exist — some upstream tar archives (e.g. the
+			// Linux elastic-agent snapshot) omit explicit directory entries.
+			if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+				t.Fatalf("failed to create parent directory for %s: %v", path, err)
+			}
+			w, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode.Perm())
+			if err != nil {
+				t.Fatalf("failed to create file %s: %v", path, err)
+			}
+			if _, err := io.Copy(w, tarReader); err != nil {
+				w.Close()
+				t.Fatalf("failed to write file %s: %v", path, err)
+			}
+			w.Close()
+			if strings.HasSuffix(header.Name, agentName) {
+				paths.agentBinary = path
+			}
+			if strings.HasSuffix(header.Name, binaryName) {
+				paths.fleetServerBinary = path
+			}
+		case mode.Type()&os.ModeSymlink == os.ModeSymlink:
+			if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+				t.Fatalf("failed to create parent directory for symlink %s: %v", path, err)
+			}
+			if err := os.Symlink(header.Linkname, path); err != nil {
+				t.Fatalf("failed to create symlink %s: %v", path, err)
+			}
+			if strings.HasSuffix(header.Linkname, agentName) {
+				paths.agentBinary = path
+			}
+		default:
+			t.Logf("Unable to untar type=%c in file=%s", header.Typeflag, path)
+		}
+	}
+	return paths
+}
+
+// extractZip extracts a zip archive from r into destDir, returning the
+// paths to notable binaries found during extraction.
+func extractZip(t *testing.T, r io.Reader, destDir string) extractedPaths {
+	t.Helper()
+	var b bytes.Buffer
+	n, err := io.Copy(&b, r)
+	if err != nil {
+		t.Fatalf("failed to buffer zip archive: %v", err)
+	}
+
+	zipReader, err := zip.NewReader(bytes.NewReader(b.Bytes()), n)
+	if err != nil {
+		t.Fatalf("failed to create zip reader: %v", err)
+	}
+
+	var paths extractedPaths
+	for _, file := range zipReader.File {
+		path := filepath.Join(destDir, file.Name)
+		mode := file.FileInfo().Mode()
+		switch {
+		case mode.IsDir():
+			if err := os.MkdirAll(path, 0755); err != nil {
+				t.Fatalf("failed to create directory %s: %v", path, err)
+			}
+		case mode.IsRegular():
+			w, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, file.Mode())
+			if err != nil {
+				t.Fatalf("failed to create file %s: %v", path, err)
+			}
+			f, err := file.Open()
+			if err != nil {
+				w.Close()
+				t.Fatalf("failed to open zip entry %s: %v", file.Name, err)
+			}
+			if _, err := io.Copy(w, f); err != nil {
+				f.Close()
+				w.Close()
+				t.Fatalf("failed to write file %s: %v", path, err)
+			}
+			f.Close()
+			w.Close()
+			if strings.HasSuffix(file.Name, agentName) {
+				paths.agentBinary = path
+			}
+			if strings.HasSuffix(file.Name, binaryName) {
+				paths.fleetServerBinary = path
+			}
+		default:
+			t.Logf("Unable to unzip type=%+v in file=%s", mode, path)
+		}
+	}
+	return paths
+}
+
 // sha512OfFile returns the hex-encoded SHA-512 checksum of the file at path.
 func sha512OfFile(path string) (string, error) {
 	f, err := os.Open(path)

testing/e2e/agent_install_test.go

@@ -7,20 +7,14 @@
 package e2e
 
 import (
-	"archive/tar"
-	"archive/zip"
-	"bytes"
-	"compress/gzip"
 	"context"
-	"errors"
 	"fmt"
 	"html/template"
 	"io"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
-	"strings"
 	"testing"
 	"time"
 
@@ -86,121 +80,41 @@ func (suite *AgentInstallSuite) SetupSuite() {
 	suite.downloadPath = filepath.Join(os.TempDir(), "e2e-agent_install_test")
 	err = os.MkdirAll(suite.downloadPath, 0755)
 	suite.Require().NoError(err)
+	var paths extractedPaths
 	switch runtime.GOOS {
 	case "windows":
-		suite.extractZip(rc)
+		paths = extractZip(suite.T(), rc, suite.downloadPath)
 	case "darwin", "linux":
-		suite.extractTar(rc)
+		paths = extractTar(suite.T(), rc, suite.downloadPath)
 	default:
 		suite.Require().Failf("Unsupported OS", "OS %s is unsupported for tests", runtime.GOOS)
 	}
+
+	// Replace the fleet-server binary from the archive with the locally compiled version.
+	if paths.fleetServerBinary != "" {
+		suite.copyFleetServer(paths.fleetServerBinary)
+	}
+
+	suite.agentPath = paths.agentBinary
 	_, err = os.Stat(suite.agentPath)
 	suite.Require().NoError(err)
 	suite.T().Log("Setup complete.")
 }
 
-// extractZip treats the passed Reader as a zip stream and unarchives it to a temp dir
-// fleet-server binary in archive is replaced by a locally compiled version
-func (suite *AgentInstallSuite) extractZip(r io.Reader) {
+func (suite *AgentInstallSuite) copyFleetServer(destPath string) {
 	suite.T().Helper()
-	// Extract zip stream
-	var b bytes.Buffer
-	n, err := io.Copy(&b, r)
-	suite.Require().NoError(err)
-	zipReader, err := zip.NewReader(bytes.NewReader(b.Bytes()), n)
+	src, err := os.Open(suite.binaryPath)
 	suite.Require().NoError(err)
-	for _, file := range zipReader.File {
-		path := filepath.Join(suite.downloadPath, file.Name)
-		mode := file.FileInfo().Mode()
-		switch {
-		case mode.IsDir():
-			err := os.MkdirAll(path, 0755)
-			suite.Require().NoError(err)
-		case mode.IsRegular():
-			err := os.MkdirAll(filepath.Dir(path), 0755)
-			suite.Require().NoError(err)
-			w, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, file.Mode())
-			suite.Require().NoError(err)
-			if strings.HasSuffix(file.Name, binaryName) {
-				suite.copyFleetServer(w)
-				continue
-			}
-			if strings.HasSuffix(file.Name, agentName) {
-				suite.agentPath = path
-			}
-			f, err := file.Open()
-			suite.Require().NoError(err)
-			_, err = io.Copy(w, f)
-			suite.Require().NoError(err)
-			err = w.Close()
-			suite.Require().NoError(err)
-			err = f.Close()
-			suite.Require().NoError(err)
-		default:
-			suite.T().Logf("Unable to unzip type=%+v in file=%s", mode, path)
-		}
-	}
-}
+	defer src.Close()
 
-// extractTar treats the passed Reader as a tar.gz stream and unarchives it to the suite.downloadPath
-// fleet-server binary in archive is replaced by a locally compiled version
-func (suite *AgentInstallSuite) extractTar(r io.Reader) {
-	suite.T().Helper()
-	// Extract tar.gz stream
-	gs, err := gzip.NewReader(r)
+	w, err := os.OpenFile(destPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
 	suite.Require().NoError(err)
-	tarReader := tar.NewReader(gs)
-	for {
-		header, err := tarReader.Next()
-		if errors.Is(err, io.EOF) {
-			break
-		}
-		suite.Require().NoError(err)
-
-		path := filepath.Join(suite.downloadPath, header.Name)
-		mode := header.FileInfo().Mode()
-		switch {
-		case mode.IsDir():
-			err := os.MkdirAll(path, 0755)
-			suite.Require().NoError(err)
-		case mode.IsRegular():
-			err := os.MkdirAll(filepath.Dir(path), 0755)
-			suite.Require().NoError(err)
-			w, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode.Perm())
-			suite.Require().NoError(err)
-			// Use local fleet-server instead of the one from the archive
-			if strings.HasSuffix(header.Name, binaryName) {
-				suite.copyFleetServer(w)
-				continue
-			}
-			_, err = io.Copy(w, tarReader)
-			suite.Require().NoError(err)
-			err = w.Close()
-			suite.Require().NoError(err)
-		case mode.Type()&os.ModeSymlink == os.ModeSymlink:
-			err := os.MkdirAll(filepath.Dir(path), 0755)
-			suite.Require().NoError(err)
-			err = os.Symlink(header.Linkname, path)
-			suite.Require().NoError(err)
-			if strings.HasSuffix(header.Linkname, agentName) {
-				suite.agentPath = path
-			}
-		default:
-			suite.T().Logf("Unable to untar type=%c in file=%s", header.Typeflag, path)
-		}
-	}
-}
 
-func (suite *AgentInstallSuite) copyFleetServer(w io.WriteCloser) {
-	suite.T().Helper()
-	src, err := os.Open(suite.binaryPath)
-	suite.Require().NoError(err)
 	_, err = io.Copy(w, src)
 	suite.Require().NoError(err)
+
 	err = w.Close()
 	suite.Require().NoError(err)
-	err = src.Close()
-	suite.Require().NoError(err)
 }
 
 func (suite *AgentInstallSuite) TearDownSuite() {