Add auto-generated subdomain feature

When a base domain is configured on a host (e.g., apps.example.com),
deployments automatically get a subdomain ({name}.apps.example.com).
Custom --domain can still be provided to route both domains.

- Add BaseDomain field to Host state
- Add --base-domain flag to host init
- Add 'ship host set-domain' command to update base domain
- Update deploy flow to auto-generate subdomains
- Fix error display (errors were being silently swallowed)
- Remove placeholder email from Caddyfile template

1 files changed, 76 insertions, 0 deletions

diff --git a/cmd/ship/host/set_domain.go b/cmd/ship/host/set_domain.go
new file mode 100644
index 0000000..fed3b31
--- /dev/null
+++ b/cmd/ship/host/set_domain.go
@@ -0,0 +1,76 @@
+package host
+
+import (
+        "fmt"
+
+        "github.com/bdw/ship/internal/state"
+        "github.com/spf13/cobra"
+)
+
+var setDomainCmd = &cobra.Command{
+        Use:   "set-domain [domain]",
+        Short: "Set base domain for auto-generated subdomains",
+        Long: `Set the base domain used to auto-generate subdomains for deployments.
+
+When a base domain is configured (e.g., apps.example.com), every deployment
+will automatically get a subdomain ({name}.apps.example.com).
+
+Examples:
+  ship host set-domain apps.example.com    # Set base domain
+  ship host set-domain --clear             # Remove base domain`,
+        RunE: runSetDomain,
+}
+
+func init() {
+        setDomainCmd.Flags().Bool("clear", false, "Clear the base domain")
+}
+
+func runSetDomain(cmd *cobra.Command, args []string) error {
+        st, err := state.Load()
+        if err != nil {
+                return fmt.Errorf("error loading state: %w", err)
+        }
+
+        host, _ := cmd.Flags().GetString("host")
+        if host == "" {
+                host = st.GetDefaultHost()
+        }
+
+        if host == "" {
+                return fmt.Errorf("--host is required")
+        }
+
+        clear, _ := cmd.Flags().GetBool("clear")
+
+        if !clear && len(args) == 0 {
+                // Show current base domain
+                hostState := st.GetHost(host)
+                if hostState.BaseDomain == "" {
+                        fmt.Printf("No base domain configured for %s\n", host)
+                } else {
+                        fmt.Printf("Base domain for %s: %s\n", host, hostState.BaseDomain)
+                }
+                return nil
+        }
+
+        hostState := st.GetHost(host)
+
+        if clear {
+                hostState.BaseDomain = ""
+                if err := st.Save(); err != nil {
+                        return fmt.Errorf("error saving state: %w", err)
+                }
+                fmt.Printf("Cleared base domain for %s\n", host)
+                return nil
+        }
+
+        hostState.BaseDomain = args[0]
+        if err := st.Save(); err != nil {
+                return fmt.Errorf("error saving state: %w", err)
+        }
+
+        fmt.Printf("Set base domain for %s: %s\n", host, args[0])
+        fmt.Println("\nNew deployments will automatically use subdomains like:")
+        fmt.Printf("  myapp.%s\n", args[0])
+        return nil
+}