Merge pull request #9905 from justinsb/aws_ssh_user

Don't assume we always SSH as the current user

pkg/util/ssh.go

@@ -142,21 +142,44 @@ func (s *SSHTunnel) Close() error {
 	return nil
 }
 
+// Interface to allow mocking of ssh.Dial, for testing SSH
+type sshDialer interface {
+	Dial(network, addr string, config *ssh.ClientConfig) (*ssh.Client, error)
+}
+
+// Real implementation of sshDialer
+type realSSHDialer struct{}
+
+var _ sshDialer = &realSSHDialer{}
+
+func (d *realSSHDialer) Dial(network, addr string, config *ssh.ClientConfig) (*ssh.Client, error) {
+	return ssh.Dial(network, addr, config)
+}
+
 // RunSSHCommand returns the stdout, stderr, and exit code from running cmd on
-// host along with any SSH-level error.
+// host as specific user, along with any SSH-level error.
-func RunSSHCommand(cmd, host string, signer ssh.Signer) (string, string, int, error) {
+// If user=="", it will default (like SSH) to os.Getenv("USER")
+func RunSSHCommand(cmd, user, host string, signer ssh.Signer) (string, string, int, error) {
+	return runSSHCommand(&realSSHDialer{}, cmd, user, host, signer)
+}
+
+// Internal implementation of runSSHCommand, for testing
+func runSSHCommand(dialer sshDialer, cmd, user, host string, signer ssh.Signer) (string, string, int, error) {
+	if user == "" {
+		user = os.Getenv("USER")
+	}
 	// Setup the config, dial the server, and open a session.
 	config := &ssh.ClientConfig{
-		User: os.Getenv("USER"),
+		User: user,
 		Auth: []ssh.AuthMethod{ssh.PublicKeys(signer)},
 	}
-	client, err := ssh.Dial("tcp", host, config)
+	client, err := dialer.Dial("tcp", host, config)
 	if err != nil {
-		return "", "", 0, fmt.Errorf("error getting SSH client to host %s: '%v'", host, err)
+		return "", "", 0, fmt.Errorf("error getting SSH client to %s@%s: '%v'", user, host, err)
 	}
 	session, err := client.NewSession()
 	if err != nil {
-		return "", "", 0, fmt.Errorf("error creating session to host %s: '%v'", host, err)
+		return "", "", 0, fmt.Errorf("error creating session to %s@%s: '%v'", user, host, err)
 	}
 	defer session.Close()
 
@@ -176,7 +199,7 @@ func RunSSHCommand(cmd, host string, signer ssh.Signer) (string, string, int, er
 		} else {
 			// Some other kind of error happened (e.g. an IOError); consider the
 			// SSH unsuccessful.
-			err = fmt.Errorf("failed running `%s` on %s: '%v'", cmd, host, err)
+			err = fmt.Errorf("failed running `%s` on %s@%s: '%v'", cmd, user, host, err)
 		}
 	}
 	return bout.String(), berr.String(), code, err

pkg/util/ssh_test.go

@@ -24,6 +24,9 @@ import (
 
 	"github.com/golang/glog"
 	"golang.org/x/crypto/ssh"
+	"io"
+	"os"
+	"strings"
 )
 
 type testSSHServer struct {
@@ -159,3 +162,84 @@ func TestSSHTunnel(t *testing.T) {
 		t.Errorf("unexpected error: %v", err)
 	}
 }
+
+type mockSSHDialer struct {
+	network string
+	addr    string
+	config  *ssh.ClientConfig
+}
+
+func (d *mockSSHDialer) Dial(network, addr string, config *ssh.ClientConfig) (*ssh.Client, error) {
+	d.network = network
+	d.addr = addr
+	d.config = config
+	return nil, fmt.Errorf("mock error from Dial")
+}
+
+type mockSigner struct {
+}
+
+func (s *mockSigner) PublicKey() ssh.PublicKey {
+	panic("mockSigner.PublicKey not implemented")
+}
+
+func (s *mockSigner) Sign(rand io.Reader, data []byte) (*ssh.Signature, error) {
+	panic("mockSigner.Sign not implemented")
+}
+
+func TestSSHUser(t *testing.T) {
+	signer := &mockSigner{}
+
+	table := []struct {
+		title      string
+		user       string
+		host       string
+		signer     ssh.Signer
+		command    string
+		expectUser string
+	}{
+		{
+			title:      "all values provided",
+			user:       "testuser",
+			host:       "testhost",
+			signer:     signer,
+			command:    "uptime",
+			expectUser: "testuser",
+		},
+		{
+			title:      "empty user defaults to GetEnv(USER)",
+			user:       "",
+			host:       "testhost",
+			signer:     signer,
+			command:    "uptime",
+			expectUser: os.Getenv("USER"),
+		},
+	}
+
+	for _, item := range table {
+		dialer := &mockSSHDialer{}
+
+		_, _, _, err := runSSHCommand(dialer, item.command, item.user, item.host, item.signer)
+		if err == nil {
+			t.Errorf("expected error (as mock returns error); did not get one")
+		}
+		errString := err.Error()
+		if !strings.HasPrefix(errString, fmt.Sprintf("error getting SSH client to %s@%s:", item.expectUser, item.host)) {
+			t.Errorf("unexpected error: %v", errString)
+		}
+
+		if dialer.network != "tcp" {
+			t.Errorf("unexpected network: %v", dialer.network)
+		}
+
+		if dialer.config.User != item.expectUser {
+			t.Errorf("unexpected user: %v", dialer.config.User)
+		}
+		if len(dialer.config.Auth) != 1 {
+			t.Errorf("unexpected auth: %v", dialer.config.Auth)
+		}
+		// (No way to test Auth - nothing exported?)
+
+	}
+
+}

test/e2e/util.go

@@ -1161,7 +1161,9 @@ func SSH(cmd, host, provider string) (string, string, int, error) {
 		return "", "", 0, fmt.Errorf("error getting signer for provider %s: '%v'", provider, err)
 	}
 
-	return util.RunSSHCommand(cmd, host, signer)
+	user := os.Getenv("KUBE_SSH_USER")
+	// RunSSHCommand will default to Getenv("USER") if user == ""
+	return util.RunSSHCommand(cmd, user, host, signer)
 }
 
 // getSigner returns an ssh.Signer for the provider ("gce", etc.) that can be