Go agent 19.4 with openjdk 12 issue about docs.go.cd

[arvindsv]

The server and the agent can work in different java version, can't they? I mean I suppose that both are communicating on a standard communication (rest/soap).

Yes, they can be on different Java versions.

Let me explain a little bit more. The different pieces are:

• GoCD Agent Bootstrapper is what you install. Its job is to download an appropriate agent and agent launcher using the GoCD server. You installed a 19.4 bootstrapper which comes with Java 12.

• GoCD Agent Launcher: Downloaded by the bootstrapper, from the GoCD server. The launcher knows how to launch an agent.

• GoCD Agent: The agent downloaded by the bootstrapper, from the GoCD server. It knows how to run jobs, etc.

• GoCD server: You already know this. You have a 19.1 server, which supports up to Java 11.

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1. You pointed the 19.4 bootstrapper to a 19.1 server. 19.1 server has a 19.1 agent and launcher, which works only on Java 11.

2. The 19.4 bootstrapper downloads the 19.1 agent and launcher from the server and runs them using: java -jar (using Java 12).

3. When the agent or launcher launches, it checks which version of Java it is running with and errors out, since it is running on an unsupported version of Java.

You can see the code for 19.1 and the corresponding code for 19.4.

In that sense, this is not a Java mismatch between the agent and the server. It's just that the 19.1 agent, which is really what you're running (not 19.4), does not support Java 12.

To be very clear: If your server was running on Java 10 and your agent was running on Java 11 (or whatever is supported by them), then it'll work fine.

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As an aside: Because of recent Java licensing changes, and how they're planning to keep releasing new versions of Java every 6 months, this might show up more. We wrote a blog post about how we plan to handle Java versioning.

[arvindsv]

@david-77 Is this the setup you have?

• Your GoCD server is a 19.1 server.
• Your installed GoCD agent, called bootstrapper, is a 19.4 bootstrapper.

Typically, a newer agent is not guaranteed to work. An older agent should be fine. However, in this case, it looks like this is a different problem: Since the GoCD bootstrapper is from 19.4, it is bundled with Java 12. However, since the server is a 19.1, the bootstrapper downloads a 19.1 agent from the GoCD server. That 19.1 agent works with Java 8 to Java 11.

In this case you'll either need to install a 19.1 GoCD agent or provide the GoCD agent with a Java version less than 12.

I don't think the packaging is wrong, because the 19.4 GoCD agent is supposed to be used with a 19.4 or newer GoCD server. A 19.4 GoCD server (on Windows) will be bundled with Java 12.

[Edit: The bootstrapper's job is to download an appropriate "agent" JAR from the GoCD server, corresponding to the version of the server, so that it can be compatible]

[david-77]

Yes Arvindsv, my setup is as you described.
The mismactch between server and agent was my first thought, but why in this case I retrieve an java version problem in agent log ?
The server and the agent can work in different java version, can't they ?
I mean I suppose that both are communicating on a standard communication (rest/soap).
But maybe I'm wrong and they are using some java dedicated protocol which could produce this king of message on the agent side.

[david-77]

OK thanks a lot Arvindsv for this answer, this is very complete !
The situation is clear now. For the moment, i will keep my go server version and install a previous version of the bootstrapper.
Thanks again ;)