feat: auto-generate SSH key and guide auth setup in host init

- ensureSSHKey() generates ed25519 key if none exists
- If SSH auth fails, returns JSON with pubkey and setup instructions
- Provides ssh-copy-id command for easy key deployment

1 files changed, 82 insertions, 2 deletions

diff --git a/cmd/ship/host_v2.go b/cmd/ship/host_v2.go
index 6e1850c..b19c376 100644
--- a/cmd/ship/host_v2.go
+++ b/cmd/ship/host_v2.go
@@ -1,7 +1,11 @@
 package main
 
 import (
+        "encoding/json"
         "fmt"
+        "os"
+        "os/exec"
+        "path/filepath"
         "strings"
 
         "github.com/bdw/ship/internal/output"
@@ -38,10 +42,27 @@ func runHostInitV2(cmd *cobra.Command, args []string) error {
                 output.PrintAndExit(output.Err(output.ErrInvalidArgs, "--domain is required"))
         }
 
-        // Connect
+        // Ensure SSH key exists
+        keyPath, pubkey, err := ensureSSHKey()
+        if err != nil {
+                output.PrintAndExit(output.Err(output.ErrSSHAuthFailed, "failed to setup SSH key: "+err.Error()))
+        }
+
+        // Try to connect first (to verify key is authorized)
         client, err := ssh.Connect(host)
         if err != nil {
-                output.PrintAndExit(output.Err(output.ErrSSHConnectFailed, err.Error()))
+                // Connection failed - provide helpful error with pubkey
+                resp := map[string]interface{}{
+                        "status":      "error",
+                        "code":        "SSH_AUTH_FAILED",
+                        "message":     "SSH connection failed. Add this public key to your VPS authorized_keys:",
+                        "public_key":  pubkey,
+                        "key_path":    keyPath,
+                        "host":        host,
+                        "setup_command": fmt.Sprintf("ssh-copy-id -i %s %s", keyPath, host),
+                }
+                printJSON(resp)
+                os.Exit(output.ExitSSHFailed)
         }
         defer client.Close()
 
@@ -363,3 +384,62 @@ func setupGitDeployV2(client *ssh.Client, baseDomain string, hostState *state.Ho
         hostState.GitSetup = true
         return nil
 }
+
+// ensureSSHKey checks for an existing SSH key or generates a new one.
+// Returns the key path, public key contents, and any error.
+func ensureSSHKey() (keyPath string, pubkey string, err error) {
+        home, err := os.UserHomeDir()
+        if err != nil {
+                return "", "", err
+        }
+
+        // Check common key locations
+        keyPaths := []string{
+                filepath.Join(home, ".ssh", "id_ed25519"),
+                filepath.Join(home, ".ssh", "id_rsa"),
+                filepath.Join(home, ".ssh", "id_ecdsa"),
+        }
+
+        for _, kp := range keyPaths {
+                pubPath := kp + ".pub"
+                if _, err := os.Stat(kp); err == nil {
+                        if _, err := os.Stat(pubPath); err == nil {
+                                // Key exists, read public key
+                                pub, err := os.ReadFile(pubPath)
+                                if err != nil {
+                                        continue
+                                }
+                                return kp, strings.TrimSpace(string(pub)), nil
+                        }
+                }
+        }
+
+        // No key found, generate one
+        keyPath = filepath.Join(home, ".ssh", "id_ed25519")
+        sshDir := filepath.Dir(keyPath)
+
+        // Ensure .ssh directory exists
+        if err := os.MkdirAll(sshDir, 0700); err != nil {
+                return "", "", fmt.Errorf("failed to create .ssh directory: %w", err)
+        }
+
+        // Generate key
+        cmd := exec.Command("ssh-keygen", "-t", "ed25519", "-f", keyPath, "-N", "", "-C", "ship")
+        if err := cmd.Run(); err != nil {
+                return "", "", fmt.Errorf("failed to generate SSH key: %w", err)
+        }
+
+        // Read public key
+        pub, err := os.ReadFile(keyPath + ".pub")
+        if err != nil {
+                return "", "", fmt.Errorf("failed to read public key: %w", err)
+        }
+
+        return keyPath, strings.TrimSpace(string(pub)), nil
+}
+
+// printJSON outputs a value as JSON to stdout
+func printJSON(v interface{}) {
+        enc := json.NewEncoder(os.Stdout)
+        enc.Encode(v)
+}