fly pg unregister hook: update for new node names

See fly-apps/postgres-flex#251 for context

Author: Ben Iofel

flypg/cmd.go

@@ -79,8 +79,8 @@ func (pc *Command) UpdateSettings(ctx context.Context, leaderIp string, config m
 	return nil
 }
 
-func (pc *Command) UnregisterMember(ctx context.Context, leaderIP string, standbyIP string) error {
-	payload := encodeCommand(standbyIP)
+func (pc *Command) UnregisterMember(ctx context.Context, leaderIP string, standbyNodeName string) error {
+	payload := encodeCommand(standbyNodeName)
 	cmd := fmt.Sprintf("pg_unregister %s", payload)
 
 	resp, err := ssh.RunSSHCommand(ctx, pc.app, pc.dialer, leaderIP, cmd, ssh.DefaultSshUsername)

internal/command/machine/lifecycle_hooks.go

@@ -21,6 +21,7 @@ func runOnDeletionHook(ctx context.Context, app *fly.AppCompact, machine *fly.Ma
 		if err := postgres.UnregisterMember(ctx, app, machine); err != nil {
 			fmt.Fprintln(io.Out, "(failed)")
 			fmt.Fprintf(io.Out, "failed to unregister postgres member: %v\n", err)
+			return
 		}
 		fmt.Fprintln(io.Out, "(success)")
 	}

internal/command/postgres/postgres.go

@@ -208,8 +208,12 @@ func UnregisterMember(ctx context.Context, app *fly.AppCompact, machine *fly.Mac
 		return err
 	}
 
-	if err := cmd.UnregisterMember(ctx, leader.PrivateIP, machine.PrivateIP); err != nil {
-		return err
+	hostname := fmt.Sprintf("%s.vm.%s.internal", machine.ID, app.Name)
+
+	if err := cmd.UnregisterMember(ctx, leader.PrivateIP, hostname); err != nil {
+		if err2 := cmd.UnregisterMember(ctx, leader.PrivateIP, machine.PrivateIP); err2 != nil {
+			return err
+		}
 	}
 
 	return nil