Add ability to start table without metadata in zookeeper

dbms/src/Storages/StorageReplicatedMergeTree.cpp

@@ -277,6 +277,13 @@ StorageReplicatedMergeTree::StorageReplicatedMergeTree(
         return;
     }
 
+    if (attach && !current_zookeeper->exists(zookeeper_path + "/metadata"))
+    {
+        LOG_WARNING(log, "No metadata in ZooKeeper: table will be in readonly mode.");
+        is_readonly = true;
+        return;
+    }
+
     if (!attach)
     {
         if (!data.getDataParts().empty())

dbms/tests/integration/test_replication_without_zookeeper/configs/remote_servers.xml

@@ -0,0 +1,14 @@
+<yandex>
+    <remote_servers>
+        <test_cluster>
+            <shard>
+                <internal_replication>true</internal_replication>
+                <replica>
+                    <default_database>shard_0</default_database>
+                    <host>node1</host>
+                    <port>9000</port>
+                </replica>
+            </shard>
+        </test_cluster>
+    </remote_servers>
+</yandex>

dbms/tests/integration/test_replication_without_zookeeper/test.py

@@ -0,0 +1,51 @@
+import time
+import pytest
+
+from helpers.cluster import ClickHouseCluster, CLICKHOUSE_START_COMMAND
+from helpers.test_tools import assert_eq_with_retry
+
+cluster = ClickHouseCluster(__file__)
+node1 = cluster.add_instance('node1', main_configs=['configs/remote_servers.xml'], with_zookeeper=True, stay_alive=True)
+
+@pytest.fixture(scope="module")
+def start_cluster():
+    try:
+        cluster.start()
+
+        node1.query(
+        '''
+            CREATE DATABASE test;
+            CREATE TABLE test_table(date Date, id UInt32)
+            ENGINE = ReplicatedMergeTree('/clickhouse/tables/test/replicated', 'node1') ORDER BY id PARTITION BY toYYYYMM(date);
+        ''')
+
+        yield cluster
+
+    except Exception as ex:
+        print ex
+
+    finally:
+        cluster.shutdown()
+
+def drop_zk(zk):
+    zk.delete(path="/clickhouse", recursive=True)
+
+def test_startup_without_zookeeper(start_cluster):
+    node1.query("INSERT INTO test_table VALUES ('2018-10-01', 1), ('2018-10-02', 2), ('2018-10-03', 3)")
+    node1.query("SELECT COUNT(*) from test_table") == "3\n"
+    node1.query("SELECT is_readonly from system.replicas where table='test_table'") == "0\n"
+
+    cluster.run_kazoo_commands_with_retries(drop_zk)
+
+    time.sleep(5)
+    node1.query("SELECT COUNT(*) from test_table") == "3\n"
+    node1.query("SELECT is_readonly from system.replicas where table='test_table'") == "1\n"
+
+    node1.exec_in_container(["bash", "-c", "pkill clickhouse"], user='root')
+    time.sleep(5)
+
+    node1.exec_in_container(["bash", "-c", "{} --daemon".format(CLICKHOUSE_START_COMMAND)], user='root')
+    time.sleep(5)
+
+    node1.query("SELECT COUNT(*) from test_table") == "3\n"
+    node1.query("SELECT is_readonly from system.replicas where table='test_table'") == "1\n"