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fix: fix ssh auth with and without agent #154

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Merged
siherrmann merged 2 commits into from
Jan 21, 2026
Merged

fix: fix ssh auth with and without agent #154

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24aad44
fix: fix ssh auth with and without agent
siherrmann Jan 21, 2026
23c83b9
update: update fmt to log
siherrmann Jan 21, 2026
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65 changes: 40 additions & 25 deletions internal/installer/node/node.go
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Original file line number Diff line number Diff line change
Expand Up @@ -33,43 +33,59 @@ type NodeManager struct {

// getAuthMethods constructs a slice of ssh.AuthMethod, prioritizing the SSH agent.
func (n *NodeManager) getAuthMethods() ([]ssh.AuthMethod, error) {
var authMethods []ssh.AuthMethod
var signers []ssh.Signer

// 1. Get Agent Signers
if authSocket := os.Getenv("SSH_AUTH_SOCK"); authSocket != "" {
// Connect to the SSH agent's socket
conn, err := net.Dial("unix", authSocket)
if err == nil {
// Create an Agent client and use it for authentication
if conn, err := net.Dial("unix", authSocket); err == nil {
agentClient := agent.NewClient(conn)
authMethods = append(authMethods, ssh.PublicKeysCallback(agentClient.Signers))
} else {
fmt.Printf("Could not connect to SSH Agent (%s): %v\n", authSocket, err)
if s, err := agentClient.Signers(); err == nil {
signers = append(signers, s...)
}
}
}

// 2. Add Private Key (File) if needed
if n.KeyPath != "" {
// Use cached signer if available to avoid repeated passphrase prompts
shouldLoad := true

// Use cached signer if available
if n.cachedSigner != nil {
authMethods = append(authMethods, ssh.PublicKeys(n.cachedSigner))
} else {
signer, err := n.loadPrivateKey()
if err != nil {
if len(authMethods) == 0 {
return nil, err
signers = append(signers, n.cachedSigner)
shouldLoad = false
}

// Check if key is already in agent (requires .pub file)
if shouldLoad && len(signers) > 0 {
if pubBytes, err := n.FileIO.ReadFile(n.KeyPath + ".pub"); err == nil {
if targetPub, _, _, _, err := ssh.ParseAuthorizedKey(pubBytes); err == nil {
targetMarshaled := string(targetPub.Marshal())
for _, s := range signers {
if string(s.PublicKey().Marshal()) == targetMarshaled {
shouldLoad = false
break
}
}
}
fmt.Printf("Warning: %v\n", err)
} else {
}
}

// Else load from file with passphrase prompt if needed
if shouldLoad {
if signer, err := n.loadPrivateKey(); err == nil {
n.cachedSigner = signer
authMethods = append(authMethods, ssh.PublicKeys(signer))
signers = append(signers, signer)
} else {
log.Printf("Warning: failed to load private key: %v\n", err)
}
}
}

if len(authMethods) == 0 {
if len(signers) == 0 {
return nil, fmt.Errorf("no valid authentication methods configured. Check SSH_AUTH_SOCK and private key path")
}

return authMethods, nil
return []ssh.AuthMethod{ssh.PublicKeys(signers...)}, nil
}

// loadPrivateKey reads and parses the private key, prompting for passphrase if needed.
Expand All @@ -89,9 +105,9 @@ func (n *NodeManager) loadPrivateKey() (ssh.Signer, error) {
}

// Key is encrypted, prompt for passphrase
fmt.Printf("Enter passphrase for key '%s': ", n.KeyPath)
log.Printf("Enter passphrase for key '%s': ", n.KeyPath)
passphrase, err := term.ReadPassword(int(syscall.Stdin))
fmt.Println()
log.Println()
if err != nil {
return nil, fmt.Errorf("failed to read passphrase: %v", err)
}
Expand Down Expand Up @@ -130,7 +146,7 @@ func (n *NodeManager) connectToJumpbox(ip, username string) (*ssh.Client, error)

// Enable Agent Forwarding on the jumpbox connection
if err := n.forwardAgent(jumpboxClient, nil); err != nil {
fmt.Printf(" Warning: Agent forwarding setup failed on jumpbox: %v\n", err)
log.Printf(" Warning: Agent forwarding setup failed on jumpbox: %v\n", err)
}

return jumpboxClient, nil
Expand Down Expand Up @@ -183,7 +199,7 @@ func (n *NodeManager) RunSSHCommand(jumpboxIp string, ip string, username string
err = n.forwardAgent(client, session)

if err != nil {
fmt.Printf(" Warning: Agent forwarding setup failed on session: %v\n", err)
log.Printf(" Warning: Agent forwarding setup failed on session: %v\n", err)
}

session.Stdout = os.Stdout
Expand All @@ -202,7 +218,6 @@ func (n *NodeManager) RunSSHCommand(jumpboxIp string, ip string, username string
}

func (n *NodeManager) GetClient(jumpboxIp string, ip string, username string) (*ssh.Client, error) {

authMethods, err := n.getAuthMethods()
if err != nil {
return nil, fmt.Errorf("failed to get authentication methods: %w", err)
Expand Down