morph: support reloading morph endpoints with SIGHUP

Add a new function `Client.Reload` that passes the `WithEndpoints` option and
closes the client if there is no endpoint in the config to which the client is
connected.
Add docs.

Closes #1871.

Signed-off-by: Andrey Butusov <[email protected]>

CHANGELOG.md

@@ -17,6 +17,7 @@ attribute, which is used for container domain name in NNS contracts (#2954)
 - `neofs-cli control object revive` command (#2968)
 - `--disable-auto-gen-tag` flag for gendoc command (#2983)
 - Docs files for cli commands to the `docs/cli-commands` folder (#2983)
+- 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

@@ -870,6 +870,10 @@ 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

@@ -10,8 +10,6 @@ Available for reconfiguration fields:
 
 ```yml
   head_timeout:
-  cache_size:
-  cache_time:
   replication_cooldown:
   object_batch_size:
   max_workers:
@@ -34,3 +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`     | If in the `endpoints` there is no endpoint that the client is connected to, try connecting to another endpoint N3. |

pkg/morph/client/client.go

@@ -56,7 +56,8 @@ type Client struct {
 
 	cfg cfg
 
-	endpoints []string
+	endpointsLock *sync.RWMutex
+	endpoints     []string
 
 	subs subscriptions
 

pkg/morph/client/constructor.go

@@ -108,12 +108,13 @@ func New(key *keys.PrivateKey, opts ...Option) (*Client, error) {
 
 	var (
 		cli = &Client{
-			cache:     newClientCache(),
-			logger:    cfg.logger,
-			acc:       acc,
-			accAddr:   accAddr,
-			cfg:       *cfg,
-			closeChan: make(chan struct{}),
+			cache:         newClientCache(),
+			logger:        cfg.logger,
+			acc:           acc,
+			accAddr:       accAddr,
+			cfg:           *cfg,
+			endpointsLock: &sync.RWMutex{},
+			closeChan:     make(chan struct{}),
 			subs: subscriptions{
 				notifyChan:             make(chan *state.ContainedNotificationEvent),
 				blockChan:              make(chan *block.Block),

pkg/morph/client/multi.go

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

pkg/morph/client/reload.go

@@ -0,0 +1,31 @@
+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.endpointsLock.Lock()
+
+	c.cfg.endpoints = cfg.endpoints
+	c.endpoints = cfg.endpoints
+
+	c.endpointsLock.Unlock()
+
+	var conn = c.conn.Load()
+	if conn == nil {
+		return
+	}
+	currentEndpoint := conn.client.Endpoint()
+
+	// RPC reconnections are costly for node, so we avoid them
+	// by using the current connection while it's alive
+	// if the current endpoint is present in the config
+	if !slices.Contains(cfg.endpoints, currentEndpoint) {
+		conn.client.Close()
+	}
+}