Deploy Raft Listener for NebulaGraph Storage service¶
Full-text index data is written to the Elasticsearch cluster asynchronously. The Raft Listener (Listener for short) is a separate process that fetches data from the Storage Service and writes them into the Elasticsearch cluster.
Prerequisites¶
- You have read and fully understood the restrictions for using full-text indexes.
- You have deployed a NebulaGraph cluster.
- You have deployed a Elasticsearch cluster.
- You have prepared one or multiple servers to run one or multiple raft listeners.
Precautions¶
- The Storage Service that you want to run as the Listener must have the same or later release with all the other Nebula Graph services in the cluster.
- For now, you can only add all Listeners to a graph space once and for all. Trying to add a new Listener to a graph space that already has a Listener will fail. To add all Listeners, set them in one statement.
Deployment process¶
Step 1: Install the Listener service¶
The Listener service uses the same binary as the storaged service. However, the configuration files are different and the processes use different ports. You can install NebulaGraph on all servers that need to deploy a Listener, but only the storaged service can be used. For details, see Install NebulaGraph by RPM or DEB Package.
Step 2: Prepare the configuration file for the Listener¶
In the etc directory, remove the suffix from nebula-storaged-listener.conf.default or nebula-storaged-listener.conf.production to nebula-storaged-listener.conf, and then modify the configuration content.
Most configurations are the same as the configurations of Storage Service. This topic only introduces the differences.
| Name | Default value | Description |
|---|---|---|
daemonize |
true |
When set to true, the process is a daemon process. |
pid_file |
pids/nebula-metad-listener.pid |
The file that records the process ID. |
meta_server_addrs |
- | IP (or hostname) and ports of all Meta services. Multiple Meta services are separated by commas. |
local_ip |
- | The local IP (or hostname) of the Listener service. Use real IP addresses instead of domain names or loopback IP addresses such as 127.0.0.1. |
port |
- | The listening port of the RPC daemon of the Listener service. |
heartbeat_interval_secs |
10 |
The heartbeat interval of the Meta service. The unit is second (s). |
listener_path |
data/listener |
The WAL directory of the Listener. Only one directory is allowed. |
data_path |
data |
For compatibility reasons, this parameter can be ignored. Fill in the default value data. |
part_man_type |
memory |
The type of the part manager. Optional values are memory and meta. |
rocksdb_batch_size |
4096 |
The default reserved bytes for batch operations. |
rocksdb_block_cache |
4 |
The default block cache size of BlockBasedTable. The unit is Megabyte (MB). |
engine_type |
rocksdb |
The type of the Storage engine, such as rocksdb, memory, etc. |
part_type |
simple |
The type of the part, such as simple, consensus, etc. |
Step 3: Start Listeners¶
To initiate the Listener, navigate to the installation path of the desired cluster and execute the following command:
./bin/nebula-storaged --flagfile etc/nebula-storaged-listener.conf
Step 4: Add Listeners to NebulaGraph¶
Connect to NebulaGraph and run USE <space> to enter the graph space that you want to create full-text indexes for. Then run the following statement to add a Listener into NebulaGraph.
ADD LISTENER ELASTICSEARCH <listener_ip:port> [,<listener_ip:port>, ...]
Warning
You must use real IPs for a Listener.
Add all Listeners in one statement completely.
nebula> ADD LISTENER ELASTICSEARCH 192.168.8.100:9789,192.168.8.101:9789;
Show Listeners¶
Run the SHOW LISTENER statement to list all Listeners.
Example¶
nebula> SHOW LISTENER;
+--------+-----------------+------------------------+-------------+
| PartId | Type | Host | Host Status |
+--------+-----------------+------------------------+-------------+
| 1 | "ELASTICSEARCH" | ""192.168.8.100":9789" | "ONLINE" |
| 2 | "ELASTICSEARCH" | ""192.168.8.100":9789" | "ONLINE" |
| 3 | "ELASTICSEARCH" | ""192.168.8.100":9789" | "ONLINE" |
+--------+-----------------+------------------------+-------------+
Remove Listeners¶
Run the REMOVE LISTENER ELASTICSEARCH statement to remove all Listeners in a graph space.
Example¶
nebula> REMOVE LISTENER ELASTICSEARCH;