feat: multihost synchronization

cmd/backrest/backrest.go

@@ -18,6 +18,7 @@ import (
 	v1 "github.com/garethgeorge/backrest/gen/go/v1"
 	"github.com/garethgeorge/backrest/gen/go/v1/v1connect"
 	"github.com/garethgeorge/backrest/internal/api"
+	syncengine "github.com/garethgeorge/backrest/internal/api/syncapi"
 	"github.com/garethgeorge/backrest/internal/auth"
 	"github.com/garethgeorge/backrest/internal/config"
 	"github.com/garethgeorge/backrest/internal/env"
@@ -124,18 +125,65 @@ func main() {
 	}()
 
 	// Create and serve the HTTP gateway
+	syncHandler := syncengine.NewBackrestSyncHandler(configStore, log)
+
+	var syncWg sync.WaitGroup
+	var syncCtxCancel context.CancelFunc
+
+	syncConfigHook := &configHookForSyncEngine{
+		store: configStore,
+		onChange: func(cfg *v1.Config) {
+			if syncCtxCancel != nil {
+				zap.L().Info("cancelling existing sync context due to config change, preparing to reinitialize sync engine")
+				syncCtxCancel()
+			}
+			syncWg.Wait()
+
+			// Start running a sync loop with this context for each distinct URI
+			reposByURI := make(map[string][]*v1.Repo)
+
+			for _, repo := range cfg.Repos {
+				if !syncengine.IsBackrestRemoteRepoURI(repo.Uri) {
+					continue
+				}
+				zap.L()
+				reposByURI[repo.Uri] = append(reposByURI[repo.Uri], repo)
+			}
+
+			if len(reposByURI) == 0 {
+				return
+			}
+
+			ctx, cancel := context.WithCancel(context.Background())
+			syncCtxCancel = cancel
+
+			for uri, repos := range reposByURI {
+				syncWg.Add(1)
+
+				zap.S().Infof("starting sync engine for URI %q serving %d repos", uri, len(repos))
+
+				go func(uri string, repos []*v1.Repo) {
+					defer syncWg.Done()
+					// Create a new sync engine for this URI
+					syncClient := syncengine.NewSyncClient(cfg.Instance, uri, log)
+					syncClient.RunSyncForRepos(ctx, repos)
+				}(uri, repos)
+			}
+		},
+	}
+
 	apiBackrestHandler := api.NewBackrestHandler(
-		configStore,
+		syncConfigHook,
 		orchestrator,
 		log,
 		logStore,
 	)
-
 	authenticator := auth.NewAuthenticator(getSecret(), configStore)
 	apiAuthenticationHandler := api.NewAuthenticationHandler(authenticator)
 
 	mux := http.NewServeMux()
 	mux.Handle(v1connect.NewAuthenticationHandler(apiAuthenticationHandler))
+	mux.Handle(v1connect.NewBackrestSyncServiceHandler(syncHandler))
 	backrestHandlerPath, backrestHandler := v1connect.NewBackrestHandler(apiBackrestHandler)
 	mux.Handle(backrestHandlerPath, auth.RequireAuthentication(backrestHandler, authenticator))
 	mux.Handle("/", webui.Handler())
@@ -294,3 +342,22 @@ func migrateBboltOplog(logstore oplog.OpStore) {
 	}
 	zap.S().Infof("migrated %d operations from old bbolt oplog to sqlite", count)
 }
+
+type configHookForSyncEngine struct {
+	store    config.ConfigStore
+	onChange func(*v1.Config)
+}
+
+var _ config.ConfigStore = &configHookForSyncEngine{}
+
+func (c *configHookForSyncEngine) Get() (*v1.Config, error) {
+	return c.store.Get()
+}
+
+func (c *configHookForSyncEngine) Update(cfg *v1.Config) error {
+	err := c.store.Update(cfg)
+	if err == nil {
+		c.onChange(cfg)
+	}
+	return err
+}