Simple checkout action failing need help debugging first action

[Fran-B]

🏷️ Discussion Type

Question

💬 Feature/Topic Area

Actions Checkout

Discussion Details

I created my first action containing multiple jobs. The first being a "setup" job that others depend upon. That "setup" job is failing with a complaint about Node.js version when I am not specifying anything that has to do with JS. The relevant section of the action is:

jobs:

  setup:
    runs-on: ubuntu-latest
    #runs:
    #  using: 'node24'
    #  main: 'main.js'
    #runs-on: ubuntu-latest

    steps:
    - name: Check out repository code
      uses: actions/checkout@v6
    - name: Set up JDK 21
      uses: actions/setup-java@v4
      with:
        java-version: '21'
        #distribution: 'temurin'
        #java-package: jdk

  build:
    needs: setup
    runs-on: ubuntu-latest

    steps:

The action looks like it is running as expected, but the "setup" job fails with the following message:

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/setup-java@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Although the provided URL has an explanation of the "20 vs. 24" issue, I do not see the actual relevance to this action since nothing is directing it to do anything that is not default.

The relevant steps were originally copied from the "Java using Ant" template.
I changed the "checkout@v4" to request v6 after researching this same error on the first run.
My "on" statement uses a "workflow_dispatch" and that all seems to be working fine.

You can see some of the other things that I tried without success in the comments.

[Fran-B]

Sorry, it looks like I was confused about the reason for failure. The "Node.js" thing was just an annoying warning.
It seems that the actual error was the need to specify a "distribution" for the "java-version". I am not sure why that is required or how I would know the available choices.
What I do know is that when I specify 'temurin', my "javac --version" step, in job "build" returns "javac 17.0.19" rather than 21. That job is currently incomplete.
So, wrong version. Therefore, I am not where I would expect.

Why is that happening?

[DhruvalAnandkar]

Hi Fran! You are exactly right about the Node.js warning and the temurin distribution.

To answer your final question about why the build job is returning Java 17 instead of Java 21: for the Java version issue the problem is that in GitHub Actions every job runs on a completely separate isolated virtual machine. When you set up Java 21 in your setup job it doesn't carry over to the build job. The build job spins up a brand new Ubuntu environment which happens to have Java 17 installed by default.

So when you set up Java 21 in the setup job, it only installed it on that specific machine. When the build job started GitHub spun up a brand new Ubuntu runner which defaults to Java 17.

To fix this, you need to run the setup-java step inside the actual build job where you plan to compile your code.

Here is how you can combine them:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Check out repository code
        uses: actions/checkout@v4 

      - name: Set up JDK 21
        uses: actions/setup-java@v4
        with:
          java-version: '21'
          distribution: 'temurin' 

      - name: Check Java version
        run: javac --version # This will now output 21!

If your workflow requires setup and build to be separate jobs you will just need to repeat that exact same setup-java step at the beginning of the build job as well.

Hope this clears things up! Let me know if it gets you unblocked and if it does, I'd appreciate it if you could mark this as the answer.

[Fran-B]

Thank you Dhruval.
I figured out the separate VM thing and hadn't expected they also used separate file systems.
My real requirement is to control the Java version in one place. I created my own action to handle that.
I still have the open questions:

1. How do I know what Java distribution to request and why is it required?
2. How do I stop the warning about Node.js?

For others who might run across this, the create custom action" is explained at
https://docs.github.com/en/actions/tutorials/create-actions/create-a-composite-action?versionId=free-pro-team%40latest&productId=actions&restPage=how-tos%2Creuse-automations

[DhruvalAnandkar]

Hey Fran! That is awesome that you built a custom composite action that is exactly the right architectural move for keeping your Java setup synced across multiple jobs without repeating code!

To wrap up your last two questions :

Why distribution is required---> Back in the old days (v1) GitHub just defaulted to one vendor. Starting in v2, they stopped assuming and made it mandatory so you don't accidentally get locked into a specific vendor's build. temurin is usually the go-to standard open-source choice.
GitHub

Stopping the Node warning---> You just need to update your action versions. The warning happens because actions/setup-java@v4 uses an older version of Node under the hood. If you update to actions/setup-java@v5 and update your checkout to actions/checkout@v7 the warning will completely disappear.

Really glad you got the VM issue figured out and leveled up to using composite actions! Let me know if you run into any snags wiring up your new custom action.

[ompatel420]

You are seeing two separate things here.

First, distribution is required because actions/setup-java no longer assumes one default JDK vendor the way the old v1 action did. From v2 onward, you must specify both distribution and java-version, and GitHub documents several supported distributions such as temurin, zulu, liberica, microsoft, corretto, oracle, and others. The docs also note that different distributions can expose different version sets, so the distribution tells the action which vendor’s builds and metadata to use.

Second, the Java 17 result in your build job happens because each GitHub Actions job runs on its own fresh runner VM. Nothing installed in setup carries over to build, so when build starts it gets the runner’s default Java unless you run actions/setup-java again in that job. GitHub’s docs explicitly say each job runs in its own virtual machine runner, and GitHub-hosted runners are new VMs.

For the Node.js warning, that is about the action runtime, not your Java version. GitHub’s setup-java repository currently shows actions/setup-java@v5 in its examples, and the latest release listed in the repo is v5.5.0. The Node 20 deprecation notice is tied to older action builds that target Node 20; upgrading to the current major version is the right way to get past that warning.

So the fix is:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6
      - uses: actions/setup-java@v5
        with:
          distribution: temurin
          java-version: '21'
      - run: javac --version

If you want one place to manage the Java setup, a composite action is fine, but it still has to be invoked in every job that needs Java because jobs do not share the same runner environment.