From 315858a04ed20ba31481908c8bb78058eea5103d Mon Sep 17 00:00:00 2001
From: hainenber <dotronghai96@gmail.com>
Date: Sat, 1 Jun 2024 16:50:34 +0700
Subject: [PATCH] fix(import/git): fix panic when use non-existent revision on
 remote

Signed-off-by: hainenber <dotronghai96@gmail.com>
---
 CHANGELOG.md                                  |  2 +
 internal/runtime/import_git_test.go           | 66 +++++++++++++++++++
 .../internal/importsource/import_git.go       |  6 +-
 3 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c543ea778a..aa79358cc0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -66,6 +66,8 @@ Main (unreleased)
   cluster instance to another could have a staleness marker inserted and result
   in a gap in metrics (@thampiotr)
 
+- Fix panic when `import.git` are given with revision non-existent on remote repo. (@hainenber)
+
 ### Other changes
 
 - `pyroscope.ebpf`, `pyroscope.java`, `pyroscope.scrape`, `pyroscope.write` and `discovery.process` components are now GA. (@korniltsev)
diff --git a/internal/runtime/import_git_test.go b/internal/runtime/import_git_test.go
index 912f28e808..ed3ffe3b5d 100644
--- a/internal/runtime/import_git_test.go
+++ b/internal/runtime/import_git_test.go
@@ -317,3 +317,69 @@ const contentsMore = `declare "add" {
         value = argument.a.value + argument.b.value + 1
     }
 }`
+
+func TestNoPanicWithNonexistentRevision(t *testing.T) {
+	testRepo := t.TempDir()
+
+	main := `
+import.git "testImport" {
+	repository = "` + testRepo + `"
+  	path = "math.alloy"
+    pull_frequency = "1s"
+    revision = "nonexistent"
+}
+
+testImport.add "cc" {
+	a = 1
+    b = 1
+}
+`
+	runGit(t, testRepo, "init", testRepo)
+
+	runGit(t, testRepo, "checkout", "-b", "testor")
+
+	math := filepath.Join(testRepo, "math.alloy")
+	err := os.WriteFile(math, []byte(contents), 0666)
+	require.NoError(t, err)
+
+	runGit(t, testRepo, "add", ".")
+
+	runGit(t, testRepo, "commit", "-m \"test\"")
+
+	defer verifyNoGoroutineLeaks(t)
+	ctrl, f := setup(t, main)
+	err = ctrl.LoadSource(f, nil)
+	require.NoError(t, err)
+	ctx, cancel := context.WithCancel(context.Background())
+
+	var wg sync.WaitGroup
+	defer func() {
+		cancel()
+		wg.Wait()
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		ctrl.Run(ctx)
+	}()
+
+	// Check for initial condition
+	require.Eventually(t, func() bool {
+		export := getExport[map[string]interface{}](t, ctrl, "", "testImport.add.cc")
+		return export["sum"] == 2
+	}, 5*time.Second, 100*time.Millisecond)
+
+	err = os.WriteFile(math, []byte(contentsMore), 0666)
+	require.NoError(t, err)
+
+	runGit(t, testRepo, "add", ".")
+
+	runGit(t, testRepo, "commit", "-m \"test2\"")
+
+	// Check for final condition.
+	require.Eventually(t, func() bool {
+		export := getExport[map[string]interface{}](t, ctrl, "", "testImport.add.cc")
+		return export["sum"] == 3
+	}, 5*time.Second, 100*time.Millisecond)
+}
diff --git a/internal/runtime/internal/importsource/import_git.go b/internal/runtime/internal/importsource/import_git.go
index 2ab507f720..7c7978f941 100644
--- a/internal/runtime/internal/importsource/import_git.go
+++ b/internal/runtime/internal/importsource/import_git.go
@@ -10,6 +10,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-kit/log"
 
 	"github.com/grafana/alloy/internal/component"
@@ -194,11 +195,12 @@ func (im *ImportGit) Update(args component.Arguments) (err error) {
 	if im.repo == nil || !reflect.DeepEqual(repoOpts, im.repoOpts) {
 		r, err := vcs.NewGitRepo(context.Background(), repoPath, repoOpts)
 		if err != nil {
+			if errors.Is(err, plumbing.ErrReferenceNotFound) || !errors.As(err, &vcs.UpdateFailedError{}) {
+				return err
+			}
 			if errors.As(err, &vcs.UpdateFailedError{}) {
 				level.Error(im.log).Log("msg", "failed to update repository", "err", err)
 				im.updateHealth(err)
-			} else {
-				return err
 			}
 		}
 		im.repo = r