How to provide additional JDBC properties for Google Cloud App Engine - google-app-engine

Question

I'm trying to connect to a PostgreSQL database from Quarkus on Google App Engine. For this, additional JDBC properties "socketFactory" and "cloudSqlInstance" must be provided. But I can't figure out how to specify these in application.properties.
According to https://quarkus.io/guides/datasource, there is a propery "quarkus.datasource.jdbc.additional-jdbc-properties". But if I try to use it, connecting fails and in the logs I see:
Unrecognized configuration key "quarkus.datasource.jdbc.additional-jdbc-properties" was provided; it will be ignored;
I'm fairly sure that the required extensions are installed.
I tried several other properties like "quarkus.datasource.additional-jdbc-properties" mentioned here, but without success. Now I've run out of ideas what to try. Is there any way to specify the required properties?
application.properties:
quarkus.package.type=uber-jar
# datasource configuration
quarkus.datasource.db-kind = postgresql
quarkus.datasource.jdbc.url = jdbc:postgresql:///counter
quarkus.datasource.username = postgres
quarkus.datasource.password = <password>
quarkus.datasource.jdbc.additional-jdbc-properties=socketFactory=com.google.cloud.sql.postgres.SocketFactory,cloudSqlInstance=<project>:<region>:<instance>
quarkus.datasource.jdbc.max-size=16
# drop and create the database at startup (use `update` to only update the schema)
quarkus.hibernate-orm.database.generation=drop-and-create
pom.xml:
<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<groupId>org.acme</groupId>
<artifactId>getting-started</artifactId>
<version>1.0.0-SNAPSHOT</version>
<properties>
<compiler-plugin.version>3.8.1</compiler-plugin.version>
<maven.compiler.parameters>true</maven.compiler.parameters>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<quarkus-plugin.version>1.10.2.Final</quarkus-plugin.version>
<quarkus.platform.artifact-id>quarkus-universe-bom</quarkus.platform.artifact-id>
<quarkus.platform.group-id>io.quarkus</quarkus.platform.group-id>
<quarkus.platform.version>1.10.2.Final</quarkus.platform.version>
<surefire-plugin.version>2.22.1</surefire-plugin.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>${quarkus.platform.group-id}</groupId>
<artifactId>${quarkus.platform.artifact-id}</artifactId>
<version>${quarkus.platform.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>libraries-bom</artifactId>
<version>16.1.0</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-arc</artifactId>
</dependency>
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-resteasy</artifactId>
</dependency>
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-hibernate-orm</artifactId>
</dependency>
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-jdbc-postgresql</artifactId>
</dependency>
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-junit5</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>io.rest-assured</groupId>
<artifactId>rest-assured</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-maven-plugin</artifactId>
<version>${quarkus-plugin.version}</version>
<extensions>true</extensions>
<executions>
<execution>
<goals>
<goal>build</goal>
<goal>generate-code</goal>
<goal>generate-code-tests</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>${compiler-plugin.version}</version>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>${surefire-plugin.version}</version>
<configuration>
<systemPropertyVariables>
<java.util.logging.manager>org.jboss.logmanager.LogManager</java.util.logging.manager>
<maven.home>${maven.home}</maven.home>
</systemPropertyVariables>
</configuration>
</plugin>
</plugins>
</build>
<profiles>
<profile>
<id>native</id>
<activation>
<property>
<name>native</name>
</property>
</activation>
<build>
<plugins>
<plugin>
<artifactId>maven-failsafe-plugin</artifactId>
<version>${surefire-plugin.version}</version>
<executions>
<execution>
<goals>
<goal>integration-test</goal>
<goal>verify</goal>
</goals>
<configuration>
<systemPropertyVariables>
<native.image.path>${project.build.directory}/${project.build.finalName}-runner</native.image.path>
<java.util.logging.manager>org.jboss.logmanager.LogManager</java.util.logging.manager>
<maven.home>${maven.home}</maven.home>
</systemPropertyVariables>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<properties>
<quarkus.package.type>native</quarkus.package.type>
</properties>
</profile>
</profiles>
</project>

Answer 1

Try with this:
quarkus.datasource.jdbc.additional-jdbc-properties.socketFactory=com.google.cloud.sql.postgres.SocketFactory
quarkus.datasource.jdbc.additional-jdbc-properties.socketFactoryArg=<project>:<region>:<instance>
PS: You don't need to use strictly a SocketFactory to connect to a CloudSQL from GAE.