content: /*
   * 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.dataflow.options;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.nio.charset.StandardCharsets;
  import java.util.Arrays;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.TimeoutException;
  import java.util.stream.Collectors;
  import org.apache.beam.sdk.options.DefaultValueFactory;
  import org.apache.beam.sdk.options.PipelineOptions;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Strings;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Factory for a default value for Google Cloud region according to
   * https://cloud.google.com/compute/docs/gcloud-compute/#default-properties. If no other default can
   * be found, returns the empty string.
   */
  @VisibleForTesting
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class DefaultGcpRegionFactory implements DefaultValueFactory<String> {
    private static final Logger LOG = LoggerFactory.getLogger(DefaultGcpRegionFactory.class);
  
    @Override
    public String create(PipelineOptions options) {
      String environmentRegion = getRegionFromEnvironment();
      if (!Strings.isNullOrEmpty(environmentRegion)) {
        LOG.info("Using default GCP region {} from $CLOUDSDK_COMPUTE_REGION", environmentRegion);
        return environmentRegion;
      }
      try {
        String gcloudRegion = getRegionFromGcloudCli(2000L);
        if (!gcloudRegion.isEmpty()) {
          LOG.info("Using default GCP region {} from gcloud CLI", gcloudRegion);
          return gcloudRegion;
        }
      } catch (Exception e) {
        // Ignore.
        LOG.debug("Unable to get gcloud compute region", e);
      }
      return "";
    }
  
    @VisibleForTesting
    public static String getRegionFromEnvironment() {
      return System.getenv("CLOUDSDK_COMPUTE_REGION");
    }
  
    @VisibleForTesting
    static String getRegionFromGcloudCli(long waitMs)
        throws IOException, InterruptedException, TimeoutException {
      Process process = startGcloud();
      try (BufferedReader reader =
              new BufferedReader(
                  new InputStreamReader(process.getInputStream(), StandardCharsets.UTF_8));
          BufferedReader errorReader =
              new BufferedReader(
                  new InputStreamReader(process.getErrorStream(), StandardCharsets.UTF_8))) {
        if (process.waitFor(waitMs, TimeUnit.MILLISECONDS) && process.exitValue() == 0) {
          return reader.lines().collect(Collectors.joining());
        } else if (process.isAlive()) {
          throw new TimeoutException("gcloud subprocess is still running. Giving up.");
        } else {
          String stderr = errorReader.lines().collect(Collectors.joining("\n"));
          throw new RuntimeException(
              String.format(
                  "gcloud exited with exit value %d. Stderr:%n%s", process.exitValue(), stderr));
        }
      }
    }
  
    @VisibleForTesting
    static Process startGcloud() throws IOException {
      ProcessBuilder pb =
          new ProcessBuilder(Arrays.asList("gcloud", "config", "get-value", "compute/region"));
      return pb.start();
    }
  }
  