Add support for ssh agent authentication

remote.go

@@ -34,6 +34,7 @@ import (
 
 	sshutil "github.com/aucloud/go-sshutil"
 	"golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh/agent"
 )
 
 type RemoteCmd struct {
@@ -107,6 +108,38 @@ func NewRemoteKeyAuthRunner(ctx context.Context, user, host, key string) (*Remot
 	return &Remote{client}, nil
 }
 
+func NewRemoteAgentAuthRunner(ctx context.Context, user, host, agentSocket string) (*Remote, error) {
+
+	if _, err := os.Stat(agentSocket); os.IsNotExist(err) {
+		return nil, fmt.Errorf("agent socket %s does not exist: %w", agentSocket, err)
+	}
+	agentConn, err := net.Dial("unix", agentSocket)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open SSH agent socket %s: %v", agentSocket, err)
+	}
+	agentClient := agent.NewClient(agentConn)
+	config := &ssh.ClientConfig{
+		User: user,
+		// FIXME: This is insecure. We should verify RSA fingerprints of hosts...
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+		Auth:            []ssh.AuthMethod{ssh.PublicKeysCallback(agentClient.Signers)},
+	}
+	addr, err := ResolveHostname(host)
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve hostname %s: %w", host, err)
+	}
+	client, err := sshutil.NewClient(
+		ctx,
+		sshutil.ConstantAddrResolver{addr},
+		config,
+		sshutil.DefaultConnectBackoff(),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to establish an SSH connection to %s: %w", host, err)
+	}
+	return &Remote{client}, nil
+}
+
 func NewRemoteKeyAuthRunnerViaJumphost(ctx context.Context, user, host, jumphost, key string) (*Remote, error) {
 	if _, err := os.Stat(key); os.IsNotExist(err) {
 		return nil, fmt.Errorf("error reading private ssh key %s: %w", key, err)

runcmd_test.go

@@ -41,7 +41,19 @@ var (
 
 /* FIXME: Mock an SSH server
 func TestKeyAuth(t *testing.T) {
-	rRunner, err := NewRemoteKeyAuthRunner(user, host, key)
+	rRunner, err := NewRemoteKeyAuthRunner(context.TODO(), user, host, key)
+	if err != nil {
+		t.Error(err)
+	}
+	if err := testRun(rRunner); err != nil {
+		t.Error(err)
+	}
+}
+*/
+
+/* FIXME: Mock an SSH server
+func TestKeyAuth(t *testing.T) {
+	rRunner, err := NewRemoteAgentAuthRunner(context.TODO(), os.Getenv("USER"), "localhost", os.Getenv("SSH_AUTH_SOCK"))
 	if err != nil {
 		t.Error(err)
 	}
@@ -58,7 +70,7 @@ func TestPassAuth(t *testing.T) {
 			os.Exit(1)
 		}
 	}()
-	rRunner, err := NewRemotePassAuthRunner(user, host, pass)
+	rRunner, err := NewRemotePassAuthRunner(context.TODO(), user, host, pass)
 	if err != nil {
 		t.Error(err)
 	}
@@ -80,7 +92,7 @@ func TestLocalRun(t *testing.T) {
 
 /* FIXME: Mock anSSH server
 func TestRemoteRun(t *testing.T) {
-	rRunner, err := NewRemoteKeyAuthRunner(user, host, key)
+	rRunner, err := NewRemoteKeyAuthRunner(context.TODO(), user, host, key)
 	if err != nil {
 		t.Error(err)
 	}
@@ -102,7 +114,7 @@ func TestLocalStartWait(t *testing.T) {
 
 /* FIXME: Mock an SSH server
 func TestRemoteStartWait(t *testing.T) {
-	rRunner, err := NewRemoteKeyAuthRunner(user, host, key)
+	rRunner, err := NewRemoteKeyAuthRunner(context.TODO(), user, host, key)
 	if err != nil {
 		t.Error(err)
 	}
@@ -242,7 +254,7 @@ func testPipe(localToRemote bool) error {
 	if err != nil {
 		return err
 	}
-	rRunner, err := NewRemoteKeyAuthRunner(user, host, key)
+	rRunner, err := NewRemoteKeyAuthRunner(context.TODO(), user, host, key)
 	if err != nil {
 		return err
 	}