Get Started with Custom Connector Plugin in Trino

If you need to create a custom connector plugin in Trino, the best way to get started is to pick up an existing connector. Trino includes a comprehensive list of native connectors of any flavor. Separation of code from the main repository is requesting some modifications to it. Those changes are easier than developing the code from scratch. Your connector inherited from Trino can be smoothly integrated back to Trino. This is the key to consider in your development.

The sample is created in CentOS 7 for Trino 393. As a Trino prototype connector is taken jmx one.

1. Copy code from plugins folder

Trino jmx plugin is located in plugin folder of Trino GitHub repository. It is a subproject of the Trino project. Copy content of trino-jmx folder to your project folder, for example, custom-jmx one. There are src folder and pom.xml file.

2. Remove parent section from pom.xml

Parent section refers to the Trino project and it does not need for your custom plugin.

<parent>
    <groupId>io.trino</groupId>
    <artifactId>trino-root</artifactId>
    <version>410-SNAPSHOT</version>
    <relativePath>../../pom.xml</relativePath>
</parent>

3. Add root elements

Those elements describe your plugin, and they usually go at very beginning. Replace those elements with your values.

<version>393</version>
<groupId>com.example.trino.plugin</groupId>
<artifactId>custom-jmx</artifactId>
<description>Trino Custom JMX Connector</description>

4. Add properties section

The elements are required by Maven compiler.

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
</properties>

5. Remove unused variables

<properties>
    <air.main.basedir>${project.parent.basedir}</air.main.basedir>
</properties>

6. Add version to each dependency

Parent pom.xml file defines versions of each dependency. Those dependencies should be added to the jmx project. Mostly of versions can be found in the parent pom.xml file, but some of them are not in the parent file, and you can download .tar.gz Trino installation package, for example, 393 release direct link https://repo1.maven.org/maven2/io/trino/trino-server/393/trino-server-393.tar.gz. Versions are there if you open plugin/jmx folder.

Original dependency

<dependency>
    <groupId>io.airlift</groupId>
    <artifactId>units</artifactId>
</dependency>

Adjusted dependency

<dependency>
    <groupId>io.airlift</groupId>
    <artifactId>units</artifactId>
    <version>1.6</version>
</dependency>

Also, you can add a variable to store version.

Define the variable in properties section.

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
    <dep.airlift.version>218</dep.airlift.version>
</properties>

Use the variable in the file

<dependency>
    <groupId>io.airlift</groupId>
    <artifactId>concurrent</artifactId>
    <version>${dep.airlift.version}</version>
</dependency>

If you miss any versions, the compiler will notify and you can address it.

7. Add io.trino.spi.Plugin file

This file is requested by SPI. The location is src\main\resources\META-INF\services. The name is io.trino.spi.Plugin.

com.example.trino.plugin.custom.JmxPlugin

8. Modify location of java file to match your package

Make structure of folders in src/java as com/example/trino/custom.

8. Replace package in each file

The folder is src/java/com/example/trino/custom. Make changes to each java file.

package com.example.trino.plugin.custom;

9. Remove checkSpiVersion line from Factory file

It is a validation of Trino plugin used in Trino. A custom plugin does not have it. The file path is src/java/com/example/trino/custom/JmxConnectorFactory.java.

@Override
public Connector create(String catalogName, Map<String, String> config, ConnectorContext context)
{
    checkSpiVersion(context, this);

    Bootstrap app = new Bootstrap(

10. Define connector name in Factory file

The file path is src/java/com/example/trino/custom/JmxConnectorFactory.java.

@Override
public String getName()
{
    return "customjmx";
}

11. Create development environment

Validate that java version is 17
```
java --version
```
Validate that minimum Maven version is 3.6.0
```
mvn --version
```
Unpack the maven-wrapper distribution files to the current project source tree
```
mvn wrapper:wrapper
```

12. Make a package

This step might bring errors if there are any issues in pom.xml file or something else.

./mvnw clean package dependency:copy-dependencies -DskipTests -DincludeScope=compile

13. Test connector

Copy files to Trino plugin folder. For example, if your folder is /var/lib/trino/data/plugin.

sudo mkdir /var/lib/trino/data/plugin/custom-jmx
sudo cp -v target/dependency/*.jar /var/lib/trino/data/plugin/custom-jmx/
sudo cp -v target/*.jar /var/lib/trino/data/plugin/custom-jmx/

Create catalog properties file
```
connector.name=customjmx
```
Restart Trino cluster
Find a new catalog with customjmx name.

Resources

Trino GitHub