Commit `62742f1870`

62742f187088804e31f93d036984ba84a251d4ee

parent: b172654262

Verified · cmc ci/build: success ci/test: success ci/vuln: success

cmc <hello@cleberg.net> · 2026-09-01 07:03 UTC

e2e: reserve every port before releasing any of them

freePort closed its listener before returning, so the kernel was free to
give the next call the same port. An instance asks for three in a row, then
fails to bind its second listener and the test that started it times out on
"gitbayd did not start listening" — attributed to whichever test drew the
collision, so it moved around and never looked like the same bug twice.

Measured on the runner host, 200 rounds of three picks: 1 collision closing
each listener before the next, 0 holding them all open until every port is
chosen. Roughly half a percent per instance, across many instances a run.

Caught in build 157:

    INFO git-daemon listening addr=[::]:33767
    INFO http listening addr=127.0.0.1:33767 tls=off
    gitbayd: listen tcp 127.0.0.1:33767: bind: address already in use

TestACMEServe and the backup restore allocate in pairs and had the same bug.

Distinct from #67, where a dropped log stream failed builds whose tests had
passed; that one truncates the log and names nothing.

Closes #68
Ref #62, #67

Layout: unified · split

e2e/acme_test.go +2 −2

	@@ -22,8 +22,8 @@ func TestACMEServe(t *testing.T) {
22	inst.proc.Process.Kill()	22	inst.proc.Process.Kill()
23	inst.proc.Wait()	23	inst.proc.Wait()
24		24
25	httpsPort := freePort(t)	25	ports := freePorts(t, 2)
26	acmeHTTPPort := freePort(t)	26	httpsPort, acmeHTTPPort := ports[0], ports[1]
27	cfg := fmt.Sprintf(`	27	cfg := fmt.Sprintf(`
28	[server]	28	[server]
29	root = %q	29	root = %q

e2e/backup_test.go +2 −2

	@@ -69,8 +69,8 @@ func TestAdminBackup(t *testing.T) {
69	if outB, err := exec.Command("tar", "-xzf", archive, "-C", root2).CombinedOutput(); err != nil {	69	if outB, err := exec.Command("tar", "-xzf", archive, "-C", root2).CombinedOutput(); err != nil {
70	t.Fatalf("extract: %v\n%s", err, outB)	70	t.Fatalf("extract: %v\n%s", err, outB)
71	}	71	}
72	port2 := freePort(t)	72	ports := freePorts(t, 2)
73	httpPort2 := freePort(t)	73	port2, httpPort2 := ports[0], ports[1]
74	config2 := filepath.Join(root2, "config.toml")	74	config2 := filepath.Join(root2, "config.toml")
75	cfg := fmt.Sprintf(`	75	cfg := fmt.Sprintf(`
76	[server]	76	[server]

e2e/ssh_test.go +48 −9

	@@ -36,14 +36,36 @@ func buildGitbayd(t *testing.T) string {
36	return bin	36	return bin
37	}	37	}
38		38
39	func freePort(t *testing.T) int {	39	// freePorts reserves n distinct ports. A port is chosen by binding :0 and
		40	// reading back what the kernel assigned, so every listener has to stay open
		41	// until all of them are picked — closing one before picking the next lets
		42	// the kernel hand out the same port again, and the instance that asked for
		43	// three then fails to bind its second listener.
		44	//
		45	// Still a narrowing rather than a guarantee: another process can take a port
		46	// between the close here and the bind in gitbayd. Distinctness within one
		47	// instance is the part that is ours.
		48	func freePorts(t *testing.T, n int) []int {
40	t.Helper()	49	t.Helper()
41	ln, err := net.Listen("tcp", "127.0.0.1:0")	50	lns := make([]net.Listener, 0, n)
42	if err != nil {	51	ports := make([]int, 0, n)
43	t.Fatal(err)	52	for i := 0; i < n; i++ {
		53	ln, err := net.Listen("tcp", "127.0.0.1:0")
		54	if err != nil {
		55	t.Fatal(err)
		56	}
		57	lns = append(lns, ln)
		58	ports = append(ports, ln.Addr().(*net.TCPAddr).Port)
44	}	59	}
45	defer ln.Close()	60	for _, ln := range lns {
46	return ln.Addr().(*net.TCPAddr).Port	61	ln.Close()
		62	}
		63	return ports
		64	}
		65
		66	func freePort(t *testing.T) int {
		67	t.Helper()
		68	return freePorts(t, 1)[0]
47	}	69	}
48		70
49	func startInstance(t testing.T) instance {	71	func startInstance(t testing.T) instance {
	@@ -53,12 +75,13 @@ func startInstance(t testing.T) instance {
53	// startInstanceWith appends extra TOML to the instance config.	75	// startInstanceWith appends extra TOML to the instance config.
54	func startInstanceWith(t testing.T, extra string) instance {	76	func startInstanceWith(t testing.T, extra string) instance {
55	t.Helper()	77	t.Helper()
		78	ports := freePorts(t, 3)
56	inst := &instance{	79	inst := &instance{
57	gitbayd: buildGitbayd(t),	80	gitbayd: buildGitbayd(t),
58	root: t.TempDir(),	81	root: t.TempDir(),
59	port: freePort(t),	82	port: ports[0],
60	httpPort: freePort(t),	83	httpPort: ports[1],
61	gitPort: freePort(t),	84	gitPort: ports[2],
62	sshDir: t.TempDir(),	85	sshDir: t.TempDir(),
63	}	86	}
64	inst.config = filepath.Join(inst.root, "config.toml")	87	inst.config = filepath.Join(inst.root, "config.toml")
	@@ -244,3 +267,19 @@ func TestControlPlaneOverBareSSH(t *testing.T) {
244	t.Fatalf("keys remove with spaced arg: exit %d (want 3), stderr %q", code, errOut)	267	t.Fatalf("keys remove with spaced arg: exit %d (want 3), stderr %q", code, errOut)
245	}	268	}
246	}	269	}
		270
		271	// freePort used to close its listener before returning, so the kernel was
		272	// free to hand the same port to the next call. An instance asks for three in
		273	// a row and then fails to bind its second listener, which surfaces as an
		274	// unrelated test timing out on "gitbayd did not start listening".
		275	func TestFreePortsAreDistinct(t *testing.T) {
		276	for round := 0; round < 50; round++ {
		277	seen := map[int]bool{}
		278	for _, p := range freePorts(t, 8) {
		279	if seen[p] {
		280	t.Fatalf("round %d: port %d issued twice in one request", round, p)
		281	}
		282	seen[p] = true
		283	}
		284	}
		285	}

Commit 62742f1870

Commit `62742f1870`