Using ZooKeeper as a registry

This guide explains how to use ZooKeeper as a registry in Dubbo-Go. The complete example is available in the dubbo-go-samples/registry/zookeeper directory.

Start ZooKeeper

Start with Docker

Run a local ZooKeeper instance with Docker:

docker run --name dubbo-go-zookeeper --rm -d -p 2181:2181 zookeeper:3.9.5

Confirm that the container is running:

docker ps --filter name=dubbo-go-zookeeper

Start from a binary distribution

Download a binary distribution from the ZooKeeper releases page. Extract the archive, copy the sample configuration, and start the service:

tar -xzf apache-zookeeper-3.9.5-bin.tar.gz
cd apache-zookeeper-3.9.5-bin
cp conf/zoo_sample.cfg conf/zoo.cfg
bin/zkServer.sh start

Check the server status:

bin/zkServer.sh status

Mode: standalone indicates that the standalone ZooKeeper server is running. Both startup methods use 127.0.0.1:2181 as the registry address.

ZooKeeper also starts its administration server on port 8080 by default. If that port is already in use, set another port in conf/zoo.cfg and restart ZooKeeper:

admin.serverPort=18080

Configure the service provider

The provider selects ZooKeeper with registry.WithZookeeper() and sets the address with registry.WithAddress():

ins, _ := dubbo.NewInstance(
	dubbo.WithName("dubbo_registry_zookeeper_server"),
	dubbo.WithRegistry(
		registry.WithZookeeper(),
		registry.WithAddress("127.0.0.1:2181"),
	),
	dubbo.WithProtocol(
		protocol.WithTriple(),
		protocol.WithPort(20000),
	),
)

The options have the following purposes:

• dubbo.WithName() sets the application name. The example uses dubbo_registry_zookeeper_server, which becomes the application node name in ZooKeeper after registration.
• dubbo.WithRegistry() adds the registry configuration.
  • registry.WithZookeeper() selects ZooKeeper as the registry.
  • registry.WithAddress() sets the ZooKeeper address. Separate multiple addresses with commas.
• dubbo.WithProtocol() adds the provider protocol configuration.
  • protocol.WithTriple() exposes the service over the Triple protocol.
  • protocol.WithPort() sets the protocol listening port to 20000.

After registration succeeds, the provider address is available under /services/dubbo_registry_zookeeper_server in ZooKeeper.

Configure the service consumer

The consumer uses the same registry address. After the client is created, Dubbo-Go subscribes to ZooKeeper and discovers the service provider:

ins, _ := dubbo.NewInstance(
	dubbo.WithName("dubbo_registry_zookeeper_client"),
	dubbo.WithRegistry(
		registry.WithZookeeper(),
		registry.WithAddress("127.0.0.1:2181"),
	),
)

The consumer also configures ZooKeeper through dubbo.WithRegistry(). It does not need a server protocol or listening port because it obtains the provider address from the registry.

Run the example

Clone the sample repository and enter the ZooKeeper example directory:

git clone https://github.com/apache/dubbo-go-samples.git
cd dubbo-go-samples/registry/zookeeper

Start the service provider

Run the following command in the first terminal:

go run ./go-server/cmd/server.go

The provider listens on port 20000. Open another terminal and send an HTTP request to verify the service:

curl \
  --header "Content-Type: application/json" \
  --data '{"name":"Dubbo"}' \
  http://localhost:20000/greet.GreetService/Greet

Expected response:

{"greeting":"Dubbo"}

Inspect the registration data

If you started ZooKeeper with the Docker command above, open the CLI inside the container:

docker exec -it dubbo-go-zookeeper zkCli.sh

For a local ZooKeeper installation, enter the distribution’s bin directory, such as $HOST_PATH/apache-zookeeper-3.9.5-bin/bin, and start the CLI:

./zkCli.sh

After the connection succeeds, query the service node:

ls /services/dubbo_registry_zookeeper_server

Expected output:

[<provider-ip>:20000]

<provider-ip> is the IP address registered by the provider and depends on the local network environment. An address using port 20000 confirms that the provider registered successfully.

Start the service consumer

Keep the provider running and execute the following command in the second terminal:

go run ./go-client/cmd/client.go

The terminal prints service discovery and invocation logs, including the following response:

Greet response: greeting:"hello world"

This response confirms that the consumer discovered the provider through ZooKeeper and invoked the service.

If you started ZooKeeper with Docker, stop the container after finishing the example:

docker stop dubbo-go-zookeeper

If you started ZooKeeper from a local distribution, return to its directory and run:

bin/zkServer.sh stop