morph: support reloading morph endpoints with SIGHUP

Add a new function `Client.Reload` that passes the `WithEndpoints` option and
updates the `Client` endpoints.
Closes the current connection and attempts to
reconnect if there is no endpoint in the config to which the client is
connected. Node service can be interrupted in this case.
Add docs.

Closes #1871.

Signed-off-by: Andrey Butusov <andrey@nspcc.io>

CHANGELOG.md

@@ -18,6 +18,7 @@ attribute, which is used for container domain name in NNS contracts (#2954)
 - `--disable-auto-gen-tag` flag for gendoc command (#2983)
 - Docs files for cli commands to the `docs/cli-commands` folder (#2983)
 - `logger.encoding` config option (#2999)
+- Reloading morph endpoints with SIGHUP (#2998)
 
 ### Fixed
 - Do not search for tombstones when handling their expiration, use local indexes instead (#2929)

cmd/neofs-node/config.go

@@ -872,6 +872,10 @@ func (c *cfg) configWatcher(ctx context.Context) {
 				continue
 			}
 
+			// Morph
+
+			c.cli.Reload(client.WithEndpoints(c.morph.endpoints))
+
 			c.log.Info("configuration has been reloaded successfully")
 		case <-ctx.Done():
 			return

docs/sighup.md

@@ -32,3 +32,9 @@ comparing paths from `shard.blobstor` section. After this we have 3 sets:
 | Changed section | Actions                                                                                                              |
 |-----------------|----------------------------------------------------------------------------------------------------------------------|
 | `path`          | If `path` is different, metabase is closed and opened with a new path. All other configuration will also be updated. |
+
+### Morph
+
+| Changed section | Actions                                                                                                                                                                                                |
+|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `endpoints`     | Updates N3 endpoints.<br/>If in the `endpoints` there is no endpoint that the client is connected to, it will attempt to connect to another endpoint N3. Node service can be interrupted in this case. |

pkg/morph/client/constructor.go

@@ -40,7 +40,8 @@ type cfg struct {
 	autoSidechainScope bool
 	signer             *transaction.Signer
 
-	endpoints []string
+	endpoints     []string
+	endpointsLock *sync.RWMutex
 
 	singleCli *rpcclient.WSClient // neo-go client for single client mode
 
@@ -63,6 +64,7 @@ func defaultConfig() *cfg {
 		signer: &transaction.Signer{
 			Scopes: transaction.CalledByEntry,
 		},
+		endpointsLock:       &sync.RWMutex{},
 		reconnectionDelay:   5 * time.Second,
 		reconnectionRetries: 5,
 	}

pkg/morph/client/multi.go

@@ -33,6 +33,9 @@ func (c *Client) switchRPC() *connection {
 }
 
 func (c *Client) connEndpoints() *connection {
+	c.cfg.endpointsLock.RLock()
+	defer c.cfg.endpointsLock.RUnlock()
+
 	// Iterate endpoints.
 	for _, e := range c.cfg.endpoints {
 		conn, err := c.newConnection(e)

pkg/morph/client/reload.go

@@ -0,0 +1,29 @@
+package client
+
+import "slices"
+
+// Reload allows runtime reconfiguration for WithEndpoints parameter.
+func (c *Client) Reload(opts ...Option) {
+	cfg := new(cfg)
+	for _, o := range opts {
+		o(cfg)
+	}
+
+	c.cfg.endpointsLock.Lock()
+
+	c.cfg.endpoints = cfg.endpoints
+
+	c.cfg.endpointsLock.Unlock()
+
+	conn := c.conn.Load()
+	if conn == nil {
+		return
+	}
+
+	// Close current connection and attempt to reconnect, if there is no endpoint
+	// in the config to which the client is connected.
+	// Node service can be interrupted in this case.
+	if slices.Contains(cfg.endpoints, conn.client.Endpoint()) {
+		conn.client.Close()
+	}
+}