Require explict tag when starting psql docker (#368)

* Require explict tag when starting psql docker

Defined a util class to return docker tag of desired PSQL version.
Class is defined in ':db' and shared by ':db' and ':core'. Used
an artifact declaration to exclude unnecesary compile dependencies.

Added a presubmit check for instantiations without explicit tag.

db/build.gradle

@@ -92,8 +92,23 @@ task schemaJar(type: Jar) {
   }
 }
 
+// Expose NomulusPostgreSql class to ':core' for compile, without leaking
+// unnecessary dependencies to the release artifacts through ':core'.
+// Jar is put in the 'compileApi' configuration.
+task compileApiJar(type: Jar) {
+  archiveBaseName = 'compile'
+  from(sourceSets.main.output) {
+    include 'google/registry/persistence/NomulusPostgreSql**'
+  }
+}
+
+configurations {
+  compileApi
+}
+
 artifacts {
   archives schemaJar
+  compileApi compileApiJar
 }
 
 publishing {

db/src/main/java/google/registry/persistence/NomulusPostgreSql.java

@@ -0,0 +1,28 @@
+// Copyright 2019 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.persistence;
+
+/** Information about Nomulus' Cloud SQL PostgreSql instance. */
+public class NomulusPostgreSql {
+
+  /** The current PostgreSql version in Cloud SQL. */
+  // TODO(weiminyu): setup periodic checks to detect version changes in Cloud SQL.
+  // TODO(weiminyu): Upgrade to 11.5, which apparently breaks JpaTransactionManagerRule.
+  private static final String TARGET_VERSION = "9.6.12";
+
+  /** Returns the docker image tag of the targeted Postgresql server version. */
+  public static String getDockerTag() {
+    return "postgres:" + TARGET_VERSION;
+  }
+}

db/src/test/java/google/registry/sql/flyway/SchemaTest.java

@@ -19,6 +19,7 @@ import static google.registry.testing.TextDiffSubject.assertThat;
 
 import com.google.common.base.Joiner;
 import com.google.common.io.Resources;
+import google.registry.persistence.NomulusPostgreSql;
 import java.io.File;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
@@ -54,7 +55,7 @@ public class SchemaTest {
    */
   @Rule
   public PostgreSQLContainer sqlContainer =
-      new PostgreSQLContainer<>("postgres:9.6.12")
+      new PostgreSQLContainer<>(NomulusPostgreSql.getDockerTag())
           .withClasspathResourceMapping(
               MOUNTED_RESOURCE_PATH, CONTAINER_MOUNT_POINT, BindMode.READ_WRITE);