Entry point for Flink REST API using external SDK driver program.

runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkJobInvoker.java

@@ -45,7 +45,7 @@ public static FlinkJobInvoker create(FlinkJobServerDriver.FlinkServerConfigurati
 
   private final FlinkJobServerDriver.FlinkServerConfiguration serverConfig;
 
-  private FlinkJobInvoker(FlinkJobServerDriver.FlinkServerConfiguration serverConfig) {
+  protected FlinkJobInvoker(FlinkJobServerDriver.FlinkServerConfiguration serverConfig) {
     super("flink-runner-job-invoker");
     this.serverConfig = serverConfig;
   }
@@ -90,7 +90,7 @@ protected JobInvocation invokeWithExecutor(
         invocationId, retrievalToken, executorService, pipeline, flinkOptions, pipelineRunner);
   }
 
-  static JobInvocation createJobInvocation(
+  protected JobInvocation createJobInvocation(
       String invocationId,
       String retrievalToken,
       ListeningExecutorService executorService,

runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkJobServerDriver.java

@@ -19,7 +19,6 @@
 
 import javax.annotation.Nullable;
 import org.apache.beam.runners.fnexecution.ServerFactory;
-import org.apache.beam.runners.fnexecution.jobsubmission.JobInvoker;
 import org.apache.beam.runners.fnexecution.jobsubmission.JobServerDriver;
 import org.apache.beam.sdk.io.FileSystems;
 import org.apache.beam.sdk.options.PipelineOptionsFactory;
@@ -61,7 +60,7 @@ public static void main(String[] args) throws Exception {
     // TODO: Expose the fileSystem related options.
     // Register standard file systems.
     FileSystems.setDefaultPipelineOptions(PipelineOptionsFactory.create());
-    fromParams(args).run();
+    fromConfig(parseArgs(args)).run();
   }
 
   private static void printUsage(CmdLineParser parser) {
@@ -71,7 +70,7 @@ private static void printUsage(CmdLineParser parser) {
     System.err.println();
   }
 
-  public static FlinkJobServerDriver fromParams(String[] args) {
+  public static FlinkServerConfiguration parseArgs(String[] args) {
     FlinkServerConfiguration configuration = new FlinkServerConfiguration();
     CmdLineParser parser = new CmdLineParser(configuration);
     try {
@@ -81,33 +80,40 @@ public static FlinkJobServerDriver fromParams(String[] args) {
       printUsage(parser);
       throw new IllegalArgumentException("Unable to parse command line arguments.", e);
     }
-
-    return fromConfig(configuration);
+    return configuration;
   }
 
   public static FlinkJobServerDriver fromConfig(FlinkServerConfiguration configuration) {
     return create(
         configuration,
         createJobServerFactory(configuration),
-        createArtifactServerFactory(configuration));
+        createArtifactServerFactory(configuration),
+        () -> FlinkJobInvoker.create(configuration));
+  }
+
+  public static FlinkJobServerDriver fromConfig(
+      FlinkServerConfiguration configuration, JobInvokerFactory jobInvokerFactory) {
+    return create(
+        configuration,
+        createJobServerFactory(configuration),
+        createArtifactServerFactory(configuration),
+        jobInvokerFactory);
   }
 
-  public static FlinkJobServerDriver create(
+  private static FlinkJobServerDriver create(
       FlinkServerConfiguration configuration,
       ServerFactory jobServerFactory,
-      ServerFactory artifactServerFactory) {
-    return new FlinkJobServerDriver(configuration, jobServerFactory, artifactServerFactory);
+      ServerFactory artifactServerFactory,
+      JobInvokerFactory jobInvokerFactory) {
+    return new FlinkJobServerDriver(
+        configuration, jobServerFactory, artifactServerFactory, jobInvokerFactory);
   }
 
   private FlinkJobServerDriver(
       FlinkServerConfiguration configuration,
       ServerFactory jobServerFactory,
-      ServerFactory artifactServerFactory) {
-    super(configuration, jobServerFactory, artifactServerFactory);
-  }
-
-  @Override
-  protected JobInvoker createJobInvoker() {
-    return FlinkJobInvoker.create((FlinkServerConfiguration) configuration);
+      ServerFactory artifactServerFactory,
+      JobInvokerFactory jobInvokerFactory) {
+    super(configuration, jobServerFactory, artifactServerFactory, jobInvokerFactory);
   }
 }

runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkPortableClientEntryPoint.java

@@ -0,0 +1,257 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.beam.runners.flink;
+
+import java.io.File;
+import java.nio.charset.Charset;
+import java.nio.file.Files;
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import org.apache.beam.model.pipeline.v1.RunnerApi;
+import org.apache.beam.runners.fnexecution.environment.ProcessManager;
+import org.apache.beam.runners.fnexecution.jobsubmission.JobInvocation;
+import org.apache.beam.runners.fnexecution.jobsubmission.JobInvoker;
+import org.apache.beam.runners.fnexecution.jobsubmission.PortablePipelineResult;
+import org.apache.beam.runners.fnexecution.jobsubmission.PortablePipelineRunner;
+import org.apache.beam.runners.fnexecution.provisioning.JobInfo;
+import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions;
+import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.ImmutableList;
+import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.util.concurrent.ListeningExecutorService;
+import org.apache.flink.api.common.time.Deadline;
+import org.kohsuke.args4j.CmdLineException;
+import org.kohsuke.args4j.CmdLineParser;
+import org.kohsuke.args4j.Option;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Flink job entry point to launch a Beam pipeline by executing an external SDK driver program.
+ *
+ * <p>Designed for non-interactive Flink REST client and container with Beam job server jar and SDK
+ * client (for example when using the FlinkK8sOperator). In the future it would be possible to
+ * support driver program execution in a separate (sidecar) container by introducing a client
+ * environment abstraction similar to how it exists for SDK workers.
+ *
+ * <p>Using this entry point eliminates the need to build jar files with materialized pipeline
+ * protos offline. Allows the driver program to access actual execution environment and services, on
+ * par with code executed by SDK workers.
+ *
+ * <p>The entry point starts the job server and provides the endpoint to the the driver program.
+ *
+ * <p>The external driver program constructs the Beam pipeline and submits it to the job service.
+ *
+ * <p>The job service defers execution of the pipeline to the plan environment and returns the
+ * "detached" status to the driver program.
+ *
+ * <p>Upon arrival of the job invocation, the entry point executes the runner, which prepares
+ * ("executes") the Flink job through the plan environment.
+ *
+ * <p>Finally Flink launches the job.
+ */
+public class FlinkPortableClientEntryPoint {
+  private static final Logger LOG = LoggerFactory.getLogger(FlinkPortableClientEntryPoint.class);
+  private static final String JOB_ENDPOINT_FLAG = "--job_endpoint";
+  private static final Duration JOB_INVOCATION_TIMEOUT = Duration.ofSeconds(30);
+  private static final Duration JOB_SERVICE_STARTUP_TIMEOUT = Duration.ofSeconds(30);
+
+  private final String driverCmd;
+  private FlinkJobServerDriver jobServer;
+  private Thread jobServerThread;
+  private DetachedJobInvokerFactory jobInvokerFactory;
+  private int jobPort = 0; // pick any free port
+
+  public FlinkPortableClientEntryPoint(String driverCmd) {
+    Preconditions.checkState(
+        !driverCmd.contains(JOB_ENDPOINT_FLAG),
+        "Driver command must not contain " + JOB_ENDPOINT_FLAG);
+    this.driverCmd = driverCmd;
+  }
+
+  /** Main method to be called within the Flink OptimizerPlanEnvironment. */
+  public static void main(String[] args) throws Exception {
+    LOG.info("entry points args: {}", Arrays.asList(args));
+    EntryPointConfiguration configuration = parseArgs(args);
+    FlinkPortableClientEntryPoint runner =
+        new FlinkPortableClientEntryPoint(configuration.driverCmd);
+    try {
+      runner.startJobService();
+      runner.runDriverProgram();
+    } catch (Exception e) {
+      throw new RuntimeException(String.format("Job %s failed.", configuration.driverCmd), e);
+    } finally {
+      LOG.info("Stopping job service");
+      runner.stopJobService();
+    }
+    LOG.info("Job submitted successfully.");
+  }
+
+  private static class EntryPointConfiguration {
+    @Option(
+        name = "--driver-cmd",
+        required = true,
+        usage =
+            "Command that launches the Python driver program. "
+                + "(The job service endpoint will be appended as --job_endpoint=localhost:<port>.)")
+    private String driverCmd;
+  }
+
+  private static EntryPointConfiguration parseArgs(String[] args) {
+    EntryPointConfiguration configuration = new EntryPointConfiguration();
+    CmdLineParser parser = new CmdLineParser(configuration);
+    try {
+      parser.parseArgument(args);
+    } catch (CmdLineException e) {
+      LOG.error("Unable to parse command line arguments.", e);
+      parser.printUsage(System.err);
+      throw new IllegalArgumentException("Unable to parse command line arguments.", e);
+    }
+    return configuration;
+  }
+
+  private void startJobService() throws Exception {
+    jobInvokerFactory = new DetachedJobInvokerFactory();
+    jobServer =
+        FlinkJobServerDriver.fromConfig(
+            FlinkJobServerDriver.parseArgs(
+                new String[] {"--job-port=" + jobPort, "--artifact-port=0", "--expansion-port=0"}),
+            jobInvokerFactory);
+    jobServerThread = new Thread(jobServer);
+    jobServerThread.start();
+
+    Deadline deadline = Deadline.fromNow(JOB_SERVICE_STARTUP_TIMEOUT);
+    while (jobServer.getJobServerUrl() == null && deadline.hasTimeLeft()) {
+      try {
+        Thread.sleep(500);
+      } catch (InterruptedException interruptEx) {
+        Thread.currentThread().interrupt();
+        throw new RuntimeException(interruptEx);
+      }
+    }
+
+    if (!jobServerThread.isAlive()) {
+      throw new IllegalStateException("Job service thread is not alive");
+    }
+
+    if (jobServer.getJobServerUrl() == null) {
+      String msg = String.format("Timeout of %s waiting for job service to start.", deadline);
+      throw new TimeoutException(msg);
+    }
+  }
+
+  private void runDriverProgram() throws Exception {
+    ProcessManager processManager = ProcessManager.create();
+    String executable = "bash";
+    List<String> args =
+        ImmutableList.of(
+            "-c",
+            String.format("%s %s=%s", driverCmd, JOB_ENDPOINT_FLAG, jobServer.getJobServerUrl()));
+    String processId = "client1";
+    File outputFile = File.createTempFile("beam-driver-program", ".log");
+
+    try {
+      final ProcessManager.RunningProcess driverProcess =
+          processManager.startProcess(processId, executable, args, System.getenv(), outputFile);
+      driverProcess.isAliveOrThrow();
+      LOG.info("Started driver program");
+
+      // await effect of the driver program submitting the job
+      jobInvokerFactory.executeDetachedJob();
+    } catch (Exception e) {
+      try {
+        processManager.stopProcess(processId);
+      } catch (Exception processKillException) {
+        e.addSuppressed(processKillException);
+      }
+      byte[] output = Files.readAllBytes(outputFile.toPath());
+      String msg =
+          String.format(
+              "Failed to start job with driver program: %s %s output: %s",
+              executable, args, new String(output, Charset.defaultCharset()));
+      throw new RuntimeException(msg, e);
+    }
+  }
+
+  private void stopJobService() throws InterruptedException {
+    if (jobServer != null) {
+      jobServer.stop();
+    }
+    if (jobServerThread != null) {
+      jobServerThread.interrupt();
+      jobServerThread.join();
+    }
+  }
+
+  private class DetachedJobInvokerFactory implements FlinkJobServerDriver.JobInvokerFactory {
+
+    private CountDownLatch latch = new CountDownLatch(1);
+    private volatile PortablePipelineRunner actualPipelineRunner;
+    private volatile RunnerApi.Pipeline pipeline;
+    private volatile JobInfo jobInfo;
+
+    private PortablePipelineRunner handoverPipelineRunner =
+        new PortablePipelineRunner() {
+          @Override
+          public PortablePipelineResult run(RunnerApi.Pipeline pipeline, JobInfo jobInfo) {
+            DetachedJobInvokerFactory.this.pipeline = pipeline;
+            DetachedJobInvokerFactory.this.jobInfo = jobInfo;
+            LOG.info("Pipeline execution handover for {}", jobInfo.jobId());
+            latch.countDown();
+            return new FlinkPortableRunnerResult.Detached();
+          }
+        };
+
+    @Override
+    public JobInvoker create() {
+      return new FlinkJobInvoker(
+          (FlinkJobServerDriver.FlinkServerConfiguration) jobServer.configuration) {
+        @Override
+        protected JobInvocation createJobInvocation(
+            String invocationId,
+            String retrievalToken,
+            ListeningExecutorService executorService,
+            RunnerApi.Pipeline pipeline,
+            FlinkPipelineOptions flinkOptions,
+            PortablePipelineRunner pipelineRunner) {
+          // replace pipeline runner to handover execution
+          actualPipelineRunner = pipelineRunner;
+          return super.createJobInvocation(
+              invocationId,
+              retrievalToken,
+              executorService,
+              pipeline,
+              flinkOptions,
+              handoverPipelineRunner);
+        }
+      };
+    }
+
+    private void executeDetachedJob() throws Exception {
+      long timeoutSeconds = JOB_INVOCATION_TIMEOUT.getSeconds();
+      if (latch.await(timeoutSeconds, TimeUnit.SECONDS)) {
+        actualPipelineRunner.run(pipeline, jobInfo);
+      } else {
+        throw new TimeoutException(
+            String.format("Timeout of %s seconds waiting for job submission.", timeoutSeconds));
+      }
+    }
+  }
+}

runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/StreamingImpulseSource.java

@@ -25,8 +25,8 @@
 import org.slf4j.LoggerFactory;
 
 /**
- * A streaming source that periodically produces a byte array. This is mostly useful for
- * debugging, or for triggering periodic behavior in a portable pipeline.
+ * A streaming source that periodically produces a byte array. This is mostly useful for debugging,
+ * or for triggering periodic behavior in a portable pipeline.
  *
  * @deprecated Legacy non-portable source which can be replaced by a DoFn with timers.
  */
@@ -59,7 +59,8 @@ public void run(SourceContext<WindowedValue<byte[]>> ctx) {
 
     while (!cancelled.get() && (messageCount == 0 || count < subtaskCount)) {
       synchronized (ctx.getCheckpointLock()) {
-        ctx.collect(WindowedValue.valueInGlobalWindow(String.valueOf(count).getBytes(Charsets.UTF_8)));
+        ctx.collect(
+            WindowedValue.valueInGlobalWindow(String.valueOf(count).getBytes(Charsets.UTF_8)));
         count++;
       }