feat: enabling regapic by giving an option to user to use http

google-cloud-datastore/pom.xml

@@ -106,10 +106,6 @@
       <groupId>com.google.oauth-client</groupId>
       <artifactId>google-oauth-client</artifactId>
     </dependency>
-    <dependency>
-      <groupId>com.google.auth</groupId>
-      <artifactId>google-auth-library-oauth2-http</artifactId>
-    </dependency>
     <dependency>
       <groupId>io.opencensus</groupId>
       <artifactId>opencensus-api</artifactId>

google-cloud-datastore/src/main/java/com/google/cloud/datastore/DatastoreOptions.java

@@ -17,6 +17,7 @@
 package com.google.cloud.datastore;
 
 import static com.google.cloud.datastore.Validator.validateNamespace;
+import static com.google.cloud.datastore.spi.v1.DatastoreRpc.Transport.GRPC;
 
 import com.google.api.core.BetaApi;
 import com.google.cloud.ServiceDefaults;
@@ -25,9 +26,12 @@
 import com.google.cloud.TransportOptions;
 import com.google.cloud.datastore.spi.DatastoreRpcFactory;
 import com.google.cloud.datastore.spi.v1.DatastoreRpc;
+import com.google.cloud.datastore.spi.v1.DatastoreRpc.Transport;
 import com.google.cloud.datastore.spi.v1.GrpcDatastoreRpc;
+import com.google.cloud.datastore.spi.v1.HttpDatastoreRpc;
 import com.google.cloud.datastore.v1.DatastoreSettings;
 import com.google.cloud.http.HttpTransportOptions;
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableSet;
 import java.io.IOException;
@@ -45,6 +49,7 @@ public class DatastoreOptions extends ServiceOptions<Datastore, DatastoreOptions
 
   private final String namespace;
   private final String databaseId;
+  private final Transport transport;
 
   public static class DefaultDatastoreFactory implements DatastoreFactory {
 
@@ -63,7 +68,9 @@ public static class DefaultDatastoreRpcFactory implements DatastoreRpcFactory {
     @Override
     public ServiceRpc create(DatastoreOptions options) {
       try {
-        return new GrpcDatastoreRpc(options);
+        return options.transport == GRPC
+            ? new GrpcDatastoreRpc(options)
+            : new HttpDatastoreRpc(options);
       } catch (IOException e) {
         throw new RuntimeException(e);
       }
@@ -74,13 +81,15 @@ public static class Builder extends ServiceOptions.Builder<Datastore, DatastoreO
 
     private String namespace;
     private String databaseId;
+    private Transport transport = GRPC;
 
     private Builder() {}
 
     private Builder(DatastoreOptions options) {
       super(options);
       namespace = options.namespace;
       databaseId = options.databaseId;
+      transport = options.transport;
     }
 
     @Override
@@ -108,12 +117,18 @@ public Builder setDatabaseId(String databaseId) {
       this.databaseId = databaseId;
       return this;
     }
+
+    public Builder setTransport(Transport transport) {
+      this.transport = transport;
+      return this;
+    }
   }
 
   private DatastoreOptions(Builder builder) {
     super(DatastoreFactory.class, DatastoreRpcFactory.class, builder, new DatastoreDefaults());
     namespace = MoreObjects.firstNonNull(builder.namespace, defaultNamespace());
     databaseId = MoreObjects.firstNonNull(builder.databaseId, DEFAULT_DATABASE_ID);
+    transport = builder.transport;
   }
 
   @Override
@@ -166,6 +181,12 @@ public String getDatabaseId() {
     return this.databaseId;
   }
 
+  /** Returns the current transport */
+  @VisibleForTesting
+  Transport getTransport() {
+    return this.transport;
+  }
+
   /** Returns a default {@code DatastoreOptions} instance. */
   public static DatastoreOptions getDefaultInstance() {
     return newBuilder().build();

google-cloud-datastore/src/main/java/com/google/cloud/datastore/spi/v1/DatastoreRpc.java

@@ -16,8 +16,11 @@
 
 package com.google.cloud.datastore.spi.v1;
 
+import com.google.api.core.InternalApi;
+import com.google.api.gax.rpc.HeaderProvider;
 import com.google.cloud.ServiceRpc;
 import com.google.cloud.datastore.DatastoreException;
+import com.google.cloud.datastore.v1.DatastoreSettings;
 import com.google.datastore.v1.AllocateIdsRequest;
 import com.google.datastore.v1.AllocateIdsResponse;
 import com.google.datastore.v1.BeginTransactionRequest;
@@ -99,7 +102,26 @@ default RunAggregationQueryResponse runAggregationQuery(RunAggregationQueryReque
 
   @Override
   void close() throws Exception;
-
   /** Returns true if this background resource has been shut down. */
   boolean isClosed();
+
+  // This class is needed solely to get access to protected method setInternalHeaderProvider()
+  class DatastoreSettingsBuilder extends DatastoreSettings.Builder {
+    DatastoreSettingsBuilder(DatastoreSettings settings) {
+      super(settings);
+    }
+
+    @Override
+    protected DatastoreSettings.Builder setInternalHeaderProvider(
+        HeaderProvider internalHeaderProvider) {
+      return super.setInternalHeaderProvider(internalHeaderProvider);
+    }
+  }
+
+  /** Transport used to sending requests. */
+  @InternalApi
+  enum Transport {
+    GRPC,
+    HTTP
+  }
 }

google-cloud-datastore/src/main/java/com/google/cloud/datastore/spi/v1/GrpcDatastoreRpc.java

@@ -18,9 +18,9 @@
 
 import static com.google.cloud.datastore.DatastoreUtils.isLocalHost;
 import static com.google.cloud.datastore.DatastoreUtils.removeScheme;
+import static com.google.cloud.datastore.spi.v1.RpcUtils.retrySettingSetter;
 import static java.util.concurrent.TimeUnit.SECONDS;
 
-import com.google.api.core.ApiFunction;
 import com.google.api.core.InternalApi;
 import com.google.api.gax.core.BackgroundResource;
 import com.google.api.gax.core.GaxProperties;
@@ -30,7 +30,6 @@
 import com.google.api.gax.rpc.HeaderProvider;
 import com.google.api.gax.rpc.NoHeaderProvider;
 import com.google.api.gax.rpc.TransportChannel;
-import com.google.api.gax.rpc.UnaryCallSettings;
 import com.google.cloud.NoCredentials;
 import com.google.cloud.ServiceOptions;
 import com.google.cloud.datastore.DatastoreException;
@@ -76,14 +75,10 @@ public GrpcDatastoreRpc(DatastoreOptions datastoreOptions) throws IOException {
           isEmulator(datastoreOptions)
               ? getClientContextForEmulator(datastoreOptions)
               : getClientContext(datastoreOptions);
-      ApiFunction<UnaryCallSettings.Builder<?, ?>, Void> retrySettingsSetter =
-          builder -> {
-            builder.setRetrySettings(datastoreOptions.getRetrySettings());
-            return null;
-          };
+
       DatastoreStubSettings datastoreStubSettings =
           DatastoreStubSettings.newBuilder(clientContext)
-              .applyToAllUnaryMethods(retrySettingsSetter)
+              .applyToAllUnaryMethods(retrySettingSetter(datastoreOptions))
               .build();
       datastoreStub = GrpcDatastoreStub.create(datastoreStubSettings);
     } catch (IOException e) {
@@ -202,18 +197,4 @@ private String getResourceToken(DatastoreOptions datastoreOptions) {
     }
     return builder.toString();
   }
-
-  // This class is needed solely to get access to protected method setInternalHeaderProvider()
-  private static class DatastoreSettingsBuilder extends DatastoreSettings.Builder {
-
-    private DatastoreSettingsBuilder(DatastoreSettings settings) {
-      super(settings);
-    }
-
-    @Override
-    protected DatastoreSettings.Builder setInternalHeaderProvider(
-        HeaderProvider internalHeaderProvider) {
-      return super.setInternalHeaderProvider(internalHeaderProvider);
-    }
-  }
 }