Add SSH SFTP backend support

internal/app/run.go

@@ -52,16 +52,23 @@ func runConfig(ctx context.Context, cfg config.Config, options RunOptions) error
 		}
 	}
 	for _, pipeline := range cfg.Pipelines {
+		if options.Stdout != nil {
+			if err := writeSSHWarnings(options.Stdout, pipeline); err != nil {
+				return err
+			}
+		}
 		sourceBackend, err := backends.openSource(ctx, pipeline.Source)
 		if err != nil {
 			return fmt.Errorf("pipeline %s: %w", pipeline.ID, err)
 		}
 		bundles, err := bundle.Discover(ctx, sourceBackend, "")
 		if err != nil {
+			closeBackend(sourceBackend)
 			return fmt.Errorf("pipeline %s discover source bundles: %w", pipeline.ID, err)
 		}
 		if options.Stdout != nil {
 			if _, err := fmt.Fprintf(options.Stdout, "- pipeline=%s source=%s bundles=%d destinations=%s\n", pipeline.ID, pipeline.Source.Backend, len(bundles), destinationSummary(pipeline.Destinations)); err != nil {
+				closeBackend(sourceBackend)
 				return err
 			}
 		}
@@ -76,6 +83,13 @@ func runConfig(ctx context.Context, cfg config.Config, options RunOptions) error
 					}
 					continue
 				}
+				closeDestination := true
+				deferCloseDestination := func() {
+					if closeDestination {
+						closeBackend(destinationBackend)
+						closeDestination = false
+					}
+				}
 				req := publish.Request{
 					PipelineID:            pipeline.ID,
 					DestinationID:         destination.ID,
@@ -97,6 +111,7 @@ func runConfig(ctx context.Context, cfg config.Config, options RunOptions) error
 					writePlanLine(options.Stdout, plan, err)
 				}
 				if err != nil {
+					deferCloseDestination()
 					failures.add(pipeline.ID, destination.ID, storage.DisplayPath(sourceBundle.RootRelativePath), err)
 					summary.recordFailure()
 					continue
@@ -104,20 +119,24 @@ func runConfig(ctx context.Context, cfg config.Config, options RunOptions) error
 				summary.recordPlan(plan.Action)
 				if !options.DryRun {
 					if err := publish.Execute(ctx, req, plan); err != nil {
+						deferCloseDestination()
 						failures.add(pipeline.ID, destination.ID, storage.DisplayPath(sourceBundle.RootRelativePath), err)
 						summary.recordFailure()
 						continue
 					}
 					if shouldNotify(plan.Action) {
 						if err := notifier.Notify(ctx, notifyEvent(plan)); err != nil {
+							deferCloseDestination()
 							failures.add(pipeline.ID, destination.ID, storage.DisplayPath(sourceBundle.RootRelativePath), err)
 							summary.recordFailure()
 							continue
 						}
 					}
 				}
+				deferCloseDestination()
 			}
 		}
+		closeBackend(sourceBackend)
 	}
 	if options.Stdout != nil {
 		if _, err := fmt.Fprintln(options.Stdout, summary.Line()); err != nil {
@@ -130,6 +149,18 @@ func runConfig(ctx context.Context, cfg config.Config, options RunOptions) error
 	return nil
 }
 
+type closeableBackend interface {
+	Close() error
+}
+
+func closeBackend(backend storage.Backend) {
+	closeable, ok := backend.(closeableBackend)
+	if !ok {
+		return
+	}
+	_ = closeable.Close()
+}
+
 func writePlanLine(w io.Writer, plan publish.Plan, planErr error) {
 	if w == nil {
 		return
@@ -174,6 +205,22 @@ func destinationSummary(destinations []config.Destination) string {
 	return strings.Join(ids, ",")
 }
 
+func writeSSHWarnings(w io.Writer, pipeline config.Pipeline) error {
+	if pipeline.Source.Backend == config.BackendSSH && pipeline.Source.SSH.HostKeyPolicy == config.HostKeyPolicyOff {
+		if _, err := fmt.Fprintf(w, "Warning: pipeline=%s source host_key_policy=off disables SSH host key checking\n", pipeline.ID); err != nil {
+			return err
+		}
+	}
+	for _, destination := range pipeline.Destinations {
+		if destination.Backend == config.BackendSSH && destination.SSH.HostKeyPolicy == config.HostKeyPolicyOff {
+			if _, err := fmt.Fprintf(w, "Warning: pipeline=%s destination=%s host_key_policy=off disables SSH host key checking\n", pipeline.ID, destination.ID); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
 func shouldNotify(action publish.Action) bool {
 	return action == publish.ActionPublishNew || action == publish.ActionReplaceOlder
 }