Add a package to open source

Add {java,tests}/google/registry/export/datastore to open source.
This is part of the migration to Datastore Managed Import/Export
for backup.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221800709

java/google/registry/export/datastore/DatastoreAdmin.java

@@ -0,0 +1,223 @@
+// Copyright 2018 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed 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 google.registry.export.datastore;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import com.google.api.client.googleapis.services.json.AbstractGoogleJsonClient;
+import com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest;
+import com.google.api.client.http.HttpRequestInitializer;
+import com.google.api.client.http.HttpTransport;
+import com.google.api.client.json.GenericJson;
+import com.google.api.client.json.JsonFactory;
+import com.google.api.client.util.Key;
+import com.google.common.base.Strings;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * Java client to <a href="https://cloud.google.com/datastore/docs/reference/admin/rest/">Cloud
+ * Datastore Admin REST API</a>.
+ */
+public class DatastoreAdmin extends AbstractGoogleJsonClient {
+
+  private static final String ROOT_URL = "https://datastore.googleapis.com/v1/";
+  private static final String SERVICE_PATH = "";
+
+  // GCP project that this instance is associated with.
+  private final String projectId;
+
+  protected DatastoreAdmin(Builder builder) {
+    super(builder);
+    this.projectId = checkNotNull(builder.projectId, "GCP projectId missing.");
+  }
+
+  /**
+   * Returns an {@link Export} request that starts exporting all Cloud Datastore databases owned by
+   * the GCP project identified by {@link #projectId}.
+   *
+   * <p>Typical usage is:
+   *
+   * <pre>
+   *     {@code Export export = datastoreAdmin.export(parameters ...);}
+   *     {@code Operation operation = export.execute();}
+   *     {@code while (!operation.isSuccessful()) { ...}}
+   * </pre>
+   *
+   * <p>Please see the <a
+   * href="https://cloud.google.com/datastore/docs/reference/admin/rest/v1/projects/export">API
+   * specification of the export method for details</a>.
+   *
+   * <p>The following undocumented behaviors with regard to {@code outputUrlPrefix} have been
+   * observed:
+   *
+   * <ul>
+   *   <li>If outputUrlPrefix refers to a GCS bucket, exported data will be nested deeper in the
+   *       bucket with a timestamped path. This is useful when periodical backups are desired
+   *   <li>If outputUrlPrefix is a already a nested path in a GCS bucket, exported data will be put
+   *       under this path. This means that a nested path is not reusable, since the export process
+   *       by default would not overwrite existing files.
+   * </ul>
+   *
+   * @param outputUrlPrefix the full resource URL of the external storage location
+   * @param kinds the datastore 'kinds' to be exported
+   */
+  public Export export(String outputUrlPrefix, List<String> kinds) {
+    return new Export(new ExportRequest(outputUrlPrefix, kinds));
+  }
+
+  /**
+   * Returns a {@link Get} request that retrieves the details of an export or import {@link
+   * Operation}.
+   *
+   * @param operationName name of the {@code Operation} as returned by an export or import request
+   */
+  public Get get(String operationName) {
+    return new Get(operationName);
+  }
+
+  /**
+   * Returns a {@link ListOperations} request that retrieves all export or import {@link Operation
+   * operations} matching {@code filter}.
+   *
+   * <p>Sample usage: find all operations started after 2018-10-31 00:00:00 UTC and has stopped:
+   *
+   * <pre>
+   *     {@code String filter = "metadata.common.startTime>\"2018-10-31T0:0:0Z\" AND done=true";}
+   *     {@code List<Operation> operations = datastoreAdmin.list(filter);}
+   * </pre>
+   *
+   * <p>Please refer to {@link Operation} for how to reference operation properties.
+   */
+  public ListOperations list(String filter) {
+    checkArgument(!Strings.isNullOrEmpty(filter), "Filter must not be null or empty.");
+    return new ListOperations(Optional.of(filter));
+  }
+
+  /**
+   * Returns a {@link ListOperations} request that retrieves all export or import {@link Operation *
+   * operations}.
+   */
+  public ListOperations listAll() {
+    return new ListOperations(Optional.empty());
+  }
+
+  /** Builder for {@link DatastoreAdmin}. */
+  public static class Builder extends AbstractGoogleJsonClient.Builder {
+
+    private String projectId;
+
+    public Builder(
+        HttpTransport httpTransport,
+        JsonFactory jsonFactory,
+        HttpRequestInitializer httpRequestInitializer) {
+      super(httpTransport, jsonFactory, ROOT_URL, SERVICE_PATH, httpRequestInitializer, false);
+    }
+
+    @Override
+    public Builder setApplicationName(String applicationName) {
+      return (Builder) super.setApplicationName(applicationName);
+    }
+
+    /** Sets the GCP project ID of the Cloud Datastore databases being managed. */
+    public Builder setProjectId(String projectId) {
+      this.projectId = projectId;
+      return this;
+    }
+
+    @Override
+    public DatastoreAdmin build() {
+      return new DatastoreAdmin(this);
+    }
+  }
+
+  /** A request to export Cloud Datastore databases. */
+  public class Export extends DatastoreAdminRequest<Operation> {
+
+    Export(ExportRequest exportRequest) {
+      super(
+          DatastoreAdmin.this,
+          "POST",
+          "projects/{projectId}:export",
+          exportRequest,
+          Operation.class);
+      set("projectId", projectId);
+    }
+  }
+
+  /** A request to retrieve details of an export or import operation. */
+  public class Get extends DatastoreAdminRequest<Operation> {
+
+    Get(String operationName) {
+      super(DatastoreAdmin.this, "GET", operationName, null, Operation.class);
+    }
+  }
+
+  /** A request to retrieve all export or import operations matching a given filter. */
+  public class ListOperations extends DatastoreAdminRequest<Operation.OperationList> {
+
+    ListOperations(Optional<String> filter) {
+      super(
+          DatastoreAdmin.this,
+          "GET",
+          "projects/{projectId}/operations",
+          null,
+          Operation.OperationList.class);
+      set("projectId", projectId);
+      filter.ifPresent(f -> set("filter", f));
+    }
+  }
+
+  /** Base class of all DatastoreAdmin requests. */
+  abstract static class DatastoreAdminRequest<T> extends AbstractGoogleJsonClientRequest<T> {
+    /**
+     * @param client Google JSON client
+     * @param requestMethod HTTP Method
+     * @param uriTemplate URI template for the path relative to the base URL. If it starts with a
+     *     "/" the base path from the base URL will be stripped out. The URI template can also be a
+     *     full URL. URI template expansion is done using {@link
+     *     com.google.api.client.http.UriTemplate#expand(String, String, Object, boolean)}
+     * @param jsonContent POJO that can be serialized into JSON content or {@code null} for none
+     * @param responseClass response class to parse into
+     */
+    protected DatastoreAdminRequest(
+        DatastoreAdmin client,
+        String requestMethod,
+        String uriTemplate,
+        Object jsonContent,
+        Class<T> responseClass) {
+      super(client, requestMethod, uriTemplate, jsonContent, responseClass);
+    }
+  }
+
+  /**
+   * Model object that describes the JSON content in an export request.
+   *
+   * <p>Please note that some properties defined in the API are excluded, e.g., {@code databaseId}
+   * (not supported by Cloud Datastore) and labels (not used by Domain Registry).
+   */
+  @SuppressWarnings("unused")
+  static class ExportRequest extends GenericJson {
+    @Key private final String outputUrlPrefix;
+    @Key private final EntityFilter entityFilter;
+
+    ExportRequest(String outputUrlPrefix, List<String> kinds) {
+      checkNotNull(outputUrlPrefix, "outputUrlPrefix");
+      this.outputUrlPrefix = outputUrlPrefix;
+      this.entityFilter = new EntityFilter(kinds);
+    }
+  }
+}