Is it possible to start a zookeeper server instance in process, say for unit tests?

Question

Calling org.apache.zookeeper.server.quorum.QuorumPeerMain.main() isn't working.

Answer 1

Netfix opensourced Curator a framework to make use of Zookeeper even more convenient. It has build in test server class. Just add this test dependency to your project descriptor be it maven, gradle or else:

org.apache.curator:curator-framework:4.0.1 org.apache.curator:curator-test:4.0.1 

And here are the test essentials.

TestingServer zkTestServer; CuratorFramework cli;  @Before public void startZookeeper() throws Exception {     zkTestServer = new TestingServer(2181);     cli = CuratorFrameworkFactory.newClient(zkTestServer.getConnectString(), new RetryOneTime(2000));     cli.start(); }  @After public void stopZookeeper() throws IOException {     cli.close();     zkTestServer.stop(); } 

With cli creating any test data is very easy (requires the curator-framework dependency).

cli.create()    .creatingParentsIfNeeded()    .forPath("/a1", "testvalue".getBytes("UTF-8")); 

Answer 2

To start ZooKeeper you have to execute ZooKeeperServerMain class.

You can use following code to start ZooKeeper in embedded mode.

Properties startupProperties = ...  QuorumPeerConfig quorumConfiguration = new QuorumPeerConfig(); try {     quorumConfiguration.parseProperties(startupProperties); } catch(Exception e) {     throw new RuntimeException(e); }  zooKeeperServer = new ZooKeeperServerMain(); final ServerConfig configuration = new ServerConfig(); configuration.readFrom(quorumConfiguration);  new Thread() {     public void run() {         try {             zooKeeperServer.runFromConfig(configuration);         } catch (IOException e) {             log.error("ZooKeeper Failed", e);         }     } }.start();