replication: allow to pass instance name as bootstrap_leader

Make it possible to specify the bootstrap leader via an instance name in
addition to its URI and UUID.

While I'm at it, change the argument order of box_check_node_name() to
comply with box_check_uuid/uri/uri_set().

Closes tarantool#8539

@TarantoolBot document
Title: `box.cfg.bootstrap_leader` accepts instance names now

The option `box.cfg.bootstrap_leader`, which specifies the desired
bootstrap leader when bootstrap_strategy is "config" now accepts
instance names.

For example, this is a valid config without replication:
```lua
box.cfg{
    instance_name = 'main-server',
    bootstrap_strategy = 'config',
    bootstrap_leader = 'main-server'
}
```

When `box.cfg` contains some entries in `replication`, the node will
bootstrap from the node which has the instance name specified in
`box.cfg.bootstrap_leader`.

This is an addition to tarantool/doc#3432

changelogs/unreleased/gh-8539-bootstrap-leader-name.md

@@ -0,0 +1,15 @@
+## feature/replication
+
+* Added the ability to set the `bootstrap_leader` configuration option to the
+  instance name of the desired bootstrap leader:
+  ```lua
+    box.cfg{
+        bootstrap_strategy = 'config',
+        bootstrap_leader = 'leader-name',
+        replication = {
+            ...
+        },
+        ...
+    }
+  ```
+  (gh-7999, gh-8539).

src/box/box.cc

@@ -1326,7 +1326,7 @@ box_check_instance_uuid(struct tt_uuid *uuid)
 
 /** Fetch an optional node name from the config. */
 static int
-box_check_node_name(const char *cfg_name, char *out)
+box_check_node_name(char *out, const char *cfg_name, bool set_diag)
 {
 	const char *name = cfg_gets(cfg_name);
 	if (name == NULL) {
@@ -1335,8 +1335,10 @@ box_check_node_name(const char *cfg_name, char *out)
 	}
 	/* Nil name is allowed as Lua box.NULL or nil. Not as "". */
 	if (!node_name_is_valid(name)) {
-		diag_set(ClientError, ER_CFG, cfg_name,
-			 "expected a valid name");
+		if (set_diag) {
+			diag_set(ClientError, ER_CFG, cfg_name,
+				 "expected a valid name");
+		}
 		return -1;
 	}
 	strlcpy(out, name, NODE_NAME_SIZE_MAX);
@@ -1346,7 +1348,7 @@ box_check_node_name(const char *cfg_name, char *out)
 static int
 box_check_instance_name(char *out)
 {
-	return box_check_node_name("instance_name", out);
+	return box_check_node_name(out, "instance_name", true);
 }
 
 static int
@@ -1357,10 +1359,11 @@ box_check_replicaset_uuid(struct tt_uuid *uuid)
 
 /** Check bootstrap_leader option validity. */
 static int
-box_check_bootstrap_leader(struct uri *uri, struct tt_uuid *uuid)
+box_check_bootstrap_leader(struct uri *uri, struct tt_uuid *uuid, char *name)
 {
 	*uuid = uuid_nil;
 	uri_create(uri, NULL);
+	*name = '\0';
 	const char *source = cfg_gets("bootstrap_leader");
 	enum bootstrap_strategy strategy = box_check_bootstrap_strategy();
 	if (strategy != BOOTSTRAP_STRATEGY_CONFIG) {
@@ -1383,21 +1386,23 @@ box_check_bootstrap_leader(struct uri *uri, struct tt_uuid *uuid)
 	/* Not a uri. Try uuid then. */
 	if (box_check_uuid(uuid, "bootstrap_leader", false) == 0)
 		return 0;
+	if (box_check_node_name(name, "bootstrap_leader", false) == 0)
+		return 0;
 	diag_set(ClientError, ER_CFG, "bootstrap_leader",
-		 "the value must be either a uri or a uuid");
+		 "the value must be either a uri, a uuid or a name");
 	return -1;
 }
 
 static int
 box_check_replicaset_name(char *out)
 {
-	return box_check_node_name("replicaset_name", out);
+	return box_check_node_name(out, "replicaset_name", true);
 }
 
 static int
 box_check_cluster_name(char *out)
 {
-	return box_check_node_name("cluster_name", out);
+	return box_check_node_name(out, "cluster_name", true);
 }
 
 static enum wal_mode
@@ -1661,6 +1666,7 @@ box_check_config(void)
 	struct tt_uuid uuid;
 	struct uri uri;
 	struct uri_set uri_set;
+	char name[NODE_NAME_SIZE_MAX];
 	box_check_say();
 	box_check_audit();
 	if (box_check_flightrec() != 0)
@@ -1696,7 +1702,7 @@ box_check_config(void)
 	box_check_replication_sync_timeout();
 	if (box_check_bootstrap_strategy() == BOOTSTRAP_STRATEGY_INVALID)
 		diag_raise();
-	if (box_check_bootstrap_leader(&uri, &uuid) != 0)
+	if (box_check_bootstrap_leader(&uri, &uuid, name) != 0)
 		diag_raise();
 	uri_destroy(&uri);
 	box_check_readahead(cfg_geti("readahead"));
@@ -1878,7 +1884,8 @@ static int
 box_set_bootstrap_leader(void)
 {
 	return box_check_bootstrap_leader(&cfg_bootstrap_leader_uri,
-					  &cfg_bootstrap_leader_uuid);
+					  &cfg_bootstrap_leader_uuid,
+					  cfg_bootstrap_leader_name);
 }
 
 /** Persist this instance as the bootstrap leader in _schema space. */

src/box/replication.cc

@@ -65,6 +65,7 @@ int replication_threads = 1;
 bool cfg_replication_anon = true;
 struct tt_uuid cfg_bootstrap_leader_uuid;
 struct uri cfg_bootstrap_leader_uri;
+char cfg_bootstrap_leader_name[NODE_NAME_SIZE_MAX];
 char cfg_instance_name[NODE_NAME_SIZE_MAX];
 
 struct replicaset replicaset;
@@ -948,6 +949,10 @@ applier_is_bootstrap_leader(const struct applier *applier)
 {
 	assert(!tt_uuid_is_nil(&applier->uuid));
 	if (bootstrap_strategy == BOOTSTRAP_STRATEGY_CONFIG) {
+		if (*cfg_bootstrap_leader_name != '\0') {
+			return strcmp(applier->ballot.instance_name,
+				      cfg_bootstrap_leader_name) == 0;
+		}
 		if (!tt_uuid_is_nil(&cfg_bootstrap_leader_uuid)) {
 			return tt_uuid_is_equal(&applier->uuid,
 						&cfg_bootstrap_leader_uuid);
@@ -1448,8 +1453,10 @@ replicaset_find_join_master_cfg(void)
 		if (applier_is_bootstrap_leader(applier))
 			leader = replica;
 	}
-	if (leader == NULL && !tt_uuid_is_equal(&cfg_bootstrap_leader_uuid,
-						&INSTANCE_UUID)) {
+	if (leader == NULL &&
+	    !tt_uuid_is_equal(&cfg_bootstrap_leader_uuid, &INSTANCE_UUID) &&
+	    (strcmp(cfg_bootstrap_leader_name, cfg_instance_name) != 0 ||
+	     *cfg_bootstrap_leader_name == '\0')) {
 		tnt_raise(ClientError, ER_CFG, "bootstrap_leader",
 			  "failed to connect to the bootstrap leader");
 	}

src/box/replication.h

@@ -137,6 +137,12 @@ extern struct tt_uuid cfg_bootstrap_leader_uuid;
  */
 extern struct uri cfg_bootstrap_leader_uri;
 
+/**
+ * The name of the bootstrap leader configured via the bootstrap_leader
+ * configuration option.
+ */
+extern char cfg_bootstrap_leader_name[];
+
 /**
  * Configured name of this instance. Might be different from the actual name if
  * the configuration is not fully applied yet.

test/replication-luatest/bootstrap_strategy_test.lua

@@ -234,10 +234,26 @@ g_config.test_uuid = function(cg)
     end)
 end
 
-g_config.after_test('test_uuid', function(cg)
-    cg.server1:stop()
+g_config.before_test('test_name', function(cg)
+    cg.replica_set = replica_set:new{}
+    cg.server1 = cg.replica_set:build_and_add_server{
+        alias = 'server1',
+        box_cfg = {
+            bootstrap_strategy = 'config',
+            bootstrap_leader = 'server1name',
+            instance_name = 'server1name',
+            replication = nil,
+        },
+    }
 end)
 
+g_config.test_name = function(cg)
+    cg.replica_set:start()
+    t.helpers.retrying({}, cg.server1.exec, cg.server1, function()
+        t.assert_equals(box.info.status, 'running', 'The server is running')
+    end)
+end
+
 g_config.before_test('test_replication_without_bootstrap_leader', function(cg)
     cg.replica_set = replica_set:new{}
     cg.server1 = cg.replica_set:build_and_add_server{
@@ -335,6 +351,7 @@ end)
 local g_config_success = t.group('gh-7999-bootstrap-strategy-config-success', {
      {leader = 'server3'},
      {leader = uuid3},
+     {leader = 'server3name'},
 })
 
 g_config_success.after_each(function(cg)
@@ -354,6 +371,7 @@ g_config_success.before_test('test_correct_bootstrap_leader', function(cg)
             bootstrap_strategy = 'config',
             bootstrap_leader = bootstrap_leader,
             instance_uuid = uuid1,
+            instance_name = 'server1name',
             replication = {
                 server.build_listen_uri('server1', cg.replica_set.id),
                 server.build_listen_uri('server2', cg.replica_set_a.id),
@@ -367,13 +385,15 @@ g_config_success.before_test('test_correct_bootstrap_leader', function(cg)
         box_cfg = {
             replicaset_uuid = uuida,
             instance_uuid = uuid2,
+            instance_name = 'server2name',
         }
     }
     cg.server3 = cg.replica_set_b:build_and_add_server{
         alias = 'server3',
         box_cfg = {
             replicaset_uuid = uuidb,
             instance_uuid = uuid3,
+            instance_name = 'server3name',
         },
     }
 end)
@@ -418,6 +438,7 @@ g_config_success.before_test('test_wait_only_for_leader', function(cg)
         box_cfg = {
             replicaset_uuid = uuidb,
             instance_uuid = uuid3,
+            instance_name = 'server3name',
         },
     }
 end)
@@ -450,8 +471,7 @@ g_config_fail.test_bad_uri_or_uuid = function(cg)
         {}, -- empty table.
         {'a'}, -- non-empty table.
         {3301},
-        'abracadabra', -- neither a URI or a UUID.
-        'z2345678-1234-1234-1234-12345678', -- not a UUID.
+        '1z345678-1234-1234-1234-12345678', -- not a UUID or a name.
     }
     local errmsg = "Incorrect value for option 'bootstrap_leader':"
     local logfile = fio.pathjoin(cfg_failure.workdir, 'cfg_failure.log')