[Java] Simplify Java worker configuration (ray-project#2938)

## What do these changes do?
Previously, Java worker configuration is complicated, because it requires setting environment variables as well as command-line arguments.

This PR aims to simplify Java worker's configuration. 
1) Configuration management is now migrated to [lightbend config](https://github.com/lightbend/config), thus doesn't require setting environment variables.
2) Many unused config items are removed.
3) Provide a simple `example.conf` file, so users can get started quickly.
4) All possible options and their default values are declared and documented in `ray.default.conf` file.

This PR also simplifies and refines the following code:
1) The process of `Ray.init()`.
2) `RunManager`.
3) `WorkerContext`. 

### How to use this configuration?
1. Copy `example.conf` into your classpath and rename it to `ray.conf`.
2. Modify/add your configuration items. The all items are declared in `ray.default.conf`.
3. You can also set the items in java system prosperities.

Note: configuration is read in this priority:
System properties > `ray.conf` > `ray.default.conf`

## Related issue number
N/A

java/README.rst

@@ -1,18 +1,15 @@
-This directory contains the java worker, with the following components.
-
--  java/api: Ray API definition
--  java/common: utilities
--  java/runtime-common: common implementation of the runtime in worker
--  java/runtime-dev: a pure-java mock implementation of the runtime for
-   fast development
--  java/runtime-native: a native implementation of the runtime
--  java/test: various tests
--  src/local\_scheduler/lib/java: JNI client library for local scheduler
--  src/plasma/lib/java: JNI client library for plasma storage
-
 Quick start
 ===========
 
+Configuration
+-------------
+Ray will read your configurations in the following order:
+
+* Java system properties: e.g., ``-Dray.home=/path/to/ray``.
+* A ``ray.conf`` file in the classpath: `example <https://github.com/ray-project/ray/java/example.conf>`_.
+
+For all available config items and default values, see `this file <https://github.com/ray-project/ray/java/runtime/src/main/resources/ray.default.conf>`_.
+
 Starting Ray
 ------------
 

java/api/pom.xml

@@ -14,4 +14,11 @@
   <description>java api for ray</description>
 
   <packaging>jar</packaging>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-log4j12</artifactId>
+    </dependency>
+  </dependencies>
 </project>

java/api/src/main/java/org/ray/api/Ray.java

@@ -2,7 +2,6 @@
 
 import java.util.List;
 import org.ray.api.id.UniqueId;
-import org.ray.api.runtime.DefaultRayRuntimeFactory;
 import org.ray.api.runtime.RayRuntime;
 import org.ray.api.runtime.RayRuntimeFactory;
 
@@ -17,7 +16,14 @@ public final class Ray extends RayCall {
    * Initialize Ray runtime with the default runtime implementation.
    */
   public static void init() {
-    init(new DefaultRayRuntimeFactory());
+    try {
+      Class clz = Class.forName("org.ray.runtime.DefaultRayRuntimeFactory");
+      RayRuntimeFactory factory = (RayRuntimeFactory) clz.newInstance();
+      init(factory);
+    } catch (Exception e) {
+      throw new RuntimeException("Failed to initialize Ray runtime.", e);
+    }
+
   }
 
   /**

java/cli/src/main/java/org/ray/cli/CommandStart.java

@@ -12,10 +12,4 @@ public class CommandStart {
   @Parameter(names = "--head", description = "start the head node")
   public boolean head;
 
-  @Parameter(names = "--config", description = "the config file of ray")
-  public String config = "";
-
-  @Parameter(names = "--overwrite", description = "the overwrite items of config")
-  public String overwrite = "";
-
 }

java/cli/src/main/java/org/ray/cli/RayCli.java

@@ -2,200 +2,80 @@
 
 import com.beust.jcommander.JCommander;
 import java.io.IOException;
-import java.util.ArrayList;
-import java.util.List;
-import org.ray.api.id.UniqueId;
-import org.ray.runtime.config.PathConfig;
-import org.ray.runtime.config.RayParameters;
-import org.ray.runtime.config.RunMode;
-import org.ray.runtime.gcs.KeyValueStoreLink;
-import org.ray.runtime.gcs.RedisClient;
-import org.ray.runtime.gcs.StateStoreProxy;
-import org.ray.runtime.gcs.StateStoreProxyImpl;
+import org.ray.runtime.config.RayConfig;
 import org.ray.runtime.runner.RunManager;
-import org.ray.runtime.runner.worker.DefaultDriver;
-import org.ray.runtime.util.config.ConfigReader;
-import org.ray.runtime.util.logger.RayLog;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 
 /**
  * Ray command line interface.
  */
 public class RayCli {
 
-  private static RayCliArgs rayArgs = new RayCliArgs();
+  private static final Logger LOGGER = LoggerFactory.getLogger(RayCli.class);
 
-  private static RunManager startRayHead(RayParameters params, PathConfig paths,
-      ConfigReader configReader) {
-    RunManager manager = new RunManager(params, paths, configReader);
+  private static RayCliArgs rayArgs = new RayCliArgs();
 
+  private static RunManager startRayHead() {
+    RayConfig rayConfig = RayConfig.create();
+    RunManager manager = new RunManager(rayConfig);
     try {
-      manager.startRayHead();
+      manager.startRayProcesses(true);
     } catch (Exception e) {
-      e.printStackTrace();
-      RayLog.core.error("error at RayCli startRayHead", e);
-      throw new RuntimeException("Ray head node start failed", e);
+      LOGGER.error("Failed to start head node.", e);
+      throw new RuntimeException("Failed to start Ray head node.", e);
     }
-
-    RayLog.core.info("Started Ray head node. Redis address: {}", manager.info().redisAddress);
+    LOGGER.info("Ray head node started. Redis address is {}", rayConfig.getRedisAddress());
     return manager;
   }
 
-  private static RunManager startRayNode(RayParameters params, PathConfig paths,
-      ConfigReader configReader) {
-    RunManager manager = new RunManager(params, paths, configReader);
-
+  private static RunManager startRayNode() {
+    RayConfig rayConfig = RayConfig.create();
+    RunManager manager = new RunManager(rayConfig);
     try {
-      manager.startRayNode();
+      manager.startRayProcesses(false);
     } catch (Exception e) {
-      e.printStackTrace();
-      RayLog.core.error("error at RayCli startRayNode", e);
-      throw new RuntimeException("Ray work node start failed, err = " + e.getMessage());
+      LOGGER.error("Failed to start work node.", e);
+      throw new RuntimeException("Failed to start work node.", e);
     }
 
-    RayLog.core.info("Started Ray work node.");
+    LOGGER.info("Ray work node started.");
     return manager;
   }
 
-  private static RunManager startProcess(CommandStart cmdStart, ConfigReader config) {
-    PathConfig paths = new PathConfig(config);
-    RayParameters params = new RayParameters(config);
-
-    // Init RayLog before using it.
-    RayLog.init(params.log_dir);
-
-    RayLog.core.info("Using IP address {} for this node.", params.node_ip_address);
+  private static RunManager startProcess(CommandStart cmdStart) {
     RunManager manager;
     if (cmdStart.head) {
-      manager = startRayHead(params, paths, config);
+      manager = startRayHead();
     } else {
-      manager = startRayNode(params, paths, config);
+      manager = startRayNode();
     }
     return manager;
   }
 
-  private static void start(CommandStart cmdStart, ConfigReader reader) {
-    startProcess(cmdStart, reader);
+  private static void start(CommandStart cmdStart) {
+    startProcess(cmdStart);
   }
 
   private static void stop(CommandStop cmdStop) {
     String[] cmd = {"/bin/sh", "-c", ""};
-
-    cmd[2] = "killall global_scheduler local_scheduler plasma_store plasma_manager";
-    try {
-      Runtime.getRuntime().exec(cmd);
-    } catch (IOException e) {
-      RayLog.core.warn("exception in killing ray processes");
-    }
-
-    cmd[2] = "kill $(ps aux | grep redis-server | grep -v grep | "
+    cmd[2] = "kill $(ps aux | grep ray | grep -v grep | "
         + "awk \'{ print $2 }\') 2> /dev/null";
     try {
       Runtime.getRuntime().exec(cmd);
     } catch (IOException e) {
-      RayLog.core.warn("exception in killing ray processes");
-    }
-
-    cmd[2] = "kill -9 $(ps aux | grep DefaultWorker | grep -v grep | "
-        + "awk \'{ print $2 }\') 2> /dev/null";
-    try {
-      Runtime.getRuntime().exec(cmd);
-    } catch (IOException e) {
-      RayLog.core.warn("exception in killing ray processes");
-    }
-  }
-
-  private static String[] buildRayRuntimeArgs(CommandSubmit cmdSubmit) {
-
-    if (cmdSubmit.redisAddress == null) {
-      throw new RuntimeException(
-          "--redis-address must be specified to submit a job");      
-    }
-
-    List<String> argList = new ArrayList<String>();
-    String section = "ray.java.start.";
-    String overwrite = "--overwrite="
-        + section + "redis_address=" + cmdSubmit.redisAddress + ";"
-        + section + "run_mode=" + "CLUSTER";
-
-    argList.add(overwrite);
-
-    if (cmdSubmit.config != null) {
-      String config = "--config=" + cmdSubmit.config;
-      argList.add(config);
+      LOGGER.error("Exception in killing ray processes.", e);
     }
-
-    String[] args = new String[argList.size()];
-    argList.toArray(args);
-
-    return args;
   }
-
-  private static void submit(CommandSubmit cmdSubmit, String configPath) throws Exception {
-    ConfigReader config = new ConfigReader(configPath, "ray.java.start.deploy=true");
-    PathConfig paths = new PathConfig(config);
-    RayParameters params = new RayParameters(config);
-    params.redis_address = cmdSubmit.redisAddress;
-    params.run_mode = RunMode.CLUSTER;
-
-    KeyValueStoreLink kvStore = new RedisClient();
-    kvStore.setAddr(cmdSubmit.redisAddress);
-    StateStoreProxy stateStoreProxy = new StateStoreProxyImpl(kvStore);
-    stateStoreProxy.initializeGlobalState();
-
-    // Init RayLog before using it.
-    RayLog.init(params.log_dir);
-    UniqueId appId = params.driver_id;
-    String appDir = "/tmp/" + cmdSubmit.className;
-
-    // Start driver process.
-    RunManager runManager = new RunManager(params, paths, config);
-    Process proc = runManager.startDriver(
-        DefaultDriver.class.getName(),
-        cmdSubmit.redisAddress,
-        appId,
-        appDir,
-        params.node_ip_address,
-        cmdSubmit.className,
-        cmdSubmit.classArgs,
-        "",
-        null);
-
-    if (null == proc) {
-      RayLog.rapp.error("Failed to start driver.");
-      return;
-    }
 
-    RayLog.rapp.info("Driver started.");
-  }
-
-  private static String getConfigPath(String config) {
-    String configPath;
-
-    if (config != null && !config.equals("")) {
-      configPath = config;
-    } else {
-      configPath = System.getenv("RAY_CONFIG");
-      if (configPath == null) {
-        configPath = System.getProperty("ray.config");
-      }
-      if (configPath == null) {
-        throw new RuntimeException(
-            "Please set config file path in env RAY_CONFIG or property ray.config");
-      }
-    }
-    return configPath;
-  }
-
-  public static void main(String[] args) throws Exception {
+  public static void main(String[] args) {
 
     CommandStart cmdStart = new CommandStart();
     CommandStop cmdStop = new CommandStop();
-    CommandSubmit cmdSubmit = new CommandSubmit();
     JCommander rayCommander = JCommander.newBuilder().addObject(rayArgs)
         .addCommand("start", cmdStart)
         .addCommand("stop", cmdStop)
-        .addCommand("submit", cmdSubmit)
         .build();
     rayCommander.parse(args);
 
@@ -210,21 +90,13 @@ public static void main(String[] args) throws Exception {
       System.exit(0);
     }
 
-    String configPath;
     switch (cmd) {
-      case "start": {
-        configPath = getConfigPath(cmdStart.config);
-        ConfigReader config = new ConfigReader(configPath, cmdStart.overwrite);
-        start(cmdStart, config);
-      }
-      break;
+      case "start":
+        start(cmdStart);
+        break;
       case "stop":
         stop(cmdStop);
         break;
-      case "submit":
-        configPath = getConfigPath(cmdSubmit.config);
-        submit(cmdSubmit, configPath);
-        break;
       default:
         rayCommander.usage();
     }

java/doc/installation.rst

@@ -57,5 +57,4 @@ Run tests
 ::
 
   # in `ray/java` directory
-  export RAY_CONFIG=ray.config.ini
   mvn test