Cloud SQL

Spring Cloud GCP adds integrations with Spring JDBC so you can run your MySQL or PostgreSQL databases in Google Cloud SQL using Spring JDBC, or other libraries that depend on it like Spring Data JPA.

The Cloud SQL support is provided by Spring Cloud GCP in the form of two Spring Boot starters, one for MySQL and another one for PostgreSQL. The role of the starters is to read configuration from properties and assume default settings so that user experience connecting to MySQL and PostgreSQL is as simple as possible.

Maven coordinates, using Spring Cloud GCP BOM:

<dependency>
    <groupId>com.google.cloud</groupId>
    <artifactId>spring-cloud-gcp-starter-sql-mysql</artifactId>
</dependency>
<dependency>
    <groupId>com.google.cloud</groupId>
    <artifactId>spring-cloud-gcp-starter-sql-postgresql</artifactId>
</dependency>

Gradle coordinates:

dependencies {
    implementation("com.google.cloud:spring-cloud-gcp-starter-sql-mysql")
    implementation("com.google.cloud:spring-cloud-gcp-starter-sql-postgresql")
}

Prerequisites

In order to use the Spring Boot Starters for Google Cloud SQL, the Google Cloud SQL API must be enabled in your GCP project.

To do that, go to the API library page of the Google Cloud Console, search for "Cloud SQL API", click the first result and enable the API.

There are several similar "Cloud SQL" results. You must access the "Google Cloud SQL API" one and enable the API from there.

Spring Boot Starter for Google Cloud SQL

The Spring Boot Starters for Google Cloud SQL provide an auto-configured DataSource object. Coupled with Spring JDBC, it provides a JdbcTemplate object bean that allows for operations such as querying and modifying a database.

public List<Map<String, Object>> listUsers() {
    return jdbcTemplate.queryForList("SELECT * FROM user;");
}

You can rely on Spring Boot data source auto-configuration to configure a DataSource bean. In other words, properties like the SQL username, spring.datasource.username, and password, spring.datasource.password can be used. There is also some configuration specific to Google Cloud SQL:

Property name

Description

Required

Default value

spring.cloud.gcp.sql.enabled

Enables or disables Cloud SQL auto configuration

No

true

spring.cloud.gcp.sql.jdbc.enabled

Enables or disables JDBC Cloud SQL auto-configuration

No

true

spring.cloud.gcp.sql.database-name

Name of the database to connect to.

Yes

spring.cloud.gcp.sql.instance-connection-name

A string containing a Google Cloud SQL instance’s project ID, region and name, each separated by a colon.

Yes

For example, my-project-id:my-region:my-instance-name.

spring.cloud.gcp.sql.ip-types

Allows you to specify a comma delimited list of preferred IP types for connecting to a Cloud SQL instance. Left unconfigured Cloud SQL Socket Factory will default it to PUBLIC,PRIVATE. See Cloud SQL Socket Factory - Specifying IP Types

No

PUBLIC,PRIVATE

spring.cloud.gcp.sql.credentials.location

File system path to the Google OAuth2 credentials private key file. Used to authenticate and authorize new connections to a Google Cloud SQL instance.

No

Default credentials provided by the Spring GCP Boot starter

spring.cloud.gcp.sql.credentials.encoded-key

Base64-encoded contents of OAuth2 account private key in JSON format. Used to authenticate and authorize new connections to a Google Cloud SQL instance.

No

Default credentials provided by the Spring GCP Boot starter

spring.cloud.gcp.sql.enableIamAuth

Specifies whether to enable IAM database authentication (PostgreSQL only).

No

False

spring.datasource.username

Database username

No

MySQL: root; PostgreSQL: postgres

spring.datasource.password

Database password

No

null

spring.datasource.driver-class-name

JDBC driver to use.

No

MySQL: com.mysql.cj.jdbc.Driver; PostgreSQL: org.postgresql.Driver
If you provide your own spring.datasource.url, it will be ignored, unless you disable Cloud SQL auto configuration with spring.cloud.gcp.sql.enabled=false or spring.cloud.gcp.sql.jdbc.enabled=false.

DataSource creation flow

Spring Boot starter for Google Cloud SQL registers a CloudSqlEnvironmentPostProcessor that provides a correctly formatted spring.datasource.url property to the environment based on the properties defined above. It also provides defaults for spring.datasource.username and spring.datasource.driver-class-name, which can be overridden. The starter also configures credentials for the JDBC connection based on the properties above.

The user properties and the properties provided by the CloudSqlEnvironmentPostProcessor are then used by Spring Boot to create the DataSource. You can select the type of connection pool (e.g., Tomcat, HikariCP, etc.) by adding their dependency to the classpath.

Using the created DataSource in conjunction with Spring JDBC provides you with a fully configured and operational JdbcTemplate object that you can use to interact with your SQL database. You can connect to your database with as little as a database and instance names.

Cloud SQL IAM database authentication

Currently, Cloud SQL only supports IAM database authentication for PostgreSQL. It allows you to connect to the database using an IAM account, rather than a predefined database username and password. You will need to do the following to enable it:

  1. In your database instance settings, turn on the cloudsql.iam_authentication flag.

  2. Add the IAM user or service account to the list of database users.

  3. In the application settings, set spring.cloud.gcp.sql.enableIamAuth to true. (Note that this will also set the database protocol sslmode to disabled, as it’s required for IAM authentication to work. However, it doesn’t compromise the security of the communication because the connection is always encrypted.)

Troubleshooting tips

Connection issues

If you’re not able to connect to a database and see an endless loop of Connecting to Cloud SQL instance […​] on IP […​], it’s likely that exceptions are being thrown and logged at a level lower than your logger’s level. This may be the case with HikariCP, if your logger is set to INFO or higher level.

To see what’s going on in the background, you should add a logback.xml file to your application resources folder, that looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <include resource="org/springframework/boot/logging/logback/base.xml"/>
  <logger name="com.zaxxer.hikari.pool" level="DEBUG"/>
</configuration>
Errors like c.g.cloud.sql.core.SslSocketFactory : Re-throwing cached exception due to attempt to refresh instance information too soon after error

If you see a lot of errors like this in a loop and can’t connect to your database, this is usually a symptom that something isn’t right with the permissions of your credentials or the Google Cloud SQL API is not enabled. Verify that the Google Cloud SQL API is enabled in the Cloud Console and that your service account has the necessary IAM roles.

To find out what’s causing the issue, you can enable DEBUG logging level as mentioned above.

PostgreSQL: java.net.SocketException: already connected issue

We found this exception to be common if your Maven project’s parent is spring-boot version 1.5.x, or in any other circumstance that would cause the version of the org.postgresql:postgresql dependency to be an older one (e.g., 9.4.1212.jre7).

To fix this, re-declare the dependency in its correct version. For example, in Maven:

<dependency>
  <groupId>org.postgresql</groupId>
  <artifactId>postgresql</artifactId>
  <version>42.1.1</version>
</dependency>

Samples

Available sample applications and codelabs: