Plugin Development - OpenLiberty/liberty-tools-eclipse Wiki

Setting up the project

  1. Clone project from git

    git clone [email protected]:OpenLiberty/liberty-tools-eclipse.git

  2. Start up Eclipse (create a new directory to use as the workspace - not the cloned repo above^)

  3. Import the projects (multiple ways to do this):

  • Using Git

    1. Click on Window > Show View > Other...

    2. Search "git" and click on Git Repositories

    3. From the Git Repositories view, right click > Add a Git Repository

    4. Add the liberty-tools-eclipse directory that you cloned in step 1.

    5. Right click on the new repo and Import Projects

  • OR

    1. File->Import -> General -> Existing Projects into Workspace

    2. In the "Select root directory" type the liberty-tools-eclipse directory that you cloned in step 1 and hit "Browse".

    3. Click to select the option "Search for nested projects".

    4. Click "Finish".

You will now see a single top-level folder in the "Project Explorer" view. You can also switch to the Java perspective and the "Package Explorer" view to see the top-level project plus the nested child projects.

Run/Debug the Liberty Tools feature from Eclipse in a child Eclipse environment

  1. Setup the target platform information (versions, addons and such).

    1. Go to releng/target-platform and open

    2. Click Set as Active Target Platform in the top Right. (This will download plugin and feature metadata from Eclipse update sites so make take a few minutes to complete).

    3. If you get red X(s), iteratively do Project->Clean (and let it rebuild automatically) and then hit the Set as Active Target Platform again and wait for the X(s) to go away. No idea why this is sometimes needed.

  2. Do a Maven build to copy the binaries in place

    1. From the top-level project, do mvn install -DskipTests=true from terminal (or right-click->Run As->Maven build ... and in the "Goals" box type in install -DskipTests=true).

    2. Navigate to the project and hit <F5> (or right-click->Refresh).

  3. Launch the plugin (this will open a "child" Eclipse window with the plugin installed)

    1. Navigate to the project (bundles/ under the top-level project)

    2. Right-click -> Run As > Eclipse Application

    • For debug set breakpoints (if desired) and do "Debug As" instead of "Run As" using the same Run/Debug Configuration
  4. Setting PATH (if necessary, you might not need if you already have it set from the parent Eclipse)

    1. Open your Run Configuration in the "Run Configurations" editor, e.g. Run As > Run Configurations > Eclipse Application

    2. From the "Environment" tab, add your PATH variable here

      • You can use the "Select" button to populate from an existing environment variable)

      • You can use the value ${env_var:PATH};<...your mvn path ...> to populate in terms of your existing PATH env var

Run tests from the command line

  1. Run all tests

    • mvn install
  2. Run a single test class (no apparent way to run individual test methods though)

    • mvn verify
  3. Run a single test class with test JVM in debug mode

    • mvn verify -DdebugPort=5005

Run/Debug tests from Eclipse in a child Eclipse environment

  1. Install the SWTBot feature

    1. Help -> Eclipse MarketPlace -> (type "swtbot" ) click "Install" button, etc.
  2. Configure the test Run/Debug configuration

    1. Right-click 'tests' project, "Run As -> Run Configurations" select "JUnit Plug-in Test" and click "New launch configuration" button in the upper-left. (Or, just do "Run As->JUnit Plug-in Test" and let Eclipse generate the run configuration for you even though it won't work the first time).

    2. In the "Test" tab of the run configuration editor (the first one selected by default) UNCHECK the "Run in UI thread" checkbox. Otherwise the tests will hang.

      • You can adjust configuration to run a test selection other than all tests. You can also set env vars if necessary in the "Environment" tab.
      • Note the "Test runner" drop-down selection should show "JUnit 5".
    3. Click "Run" to run the tests in a child Eclipse defined via the target platform.

NOTE: You can use the same configuration with "Debug As" to step through code in the debugger while exercising the tests.



  • Supported Java version: 11 and 17

  • Maven and Gradle executables must be on the PATH variable (and possibly Docker if using the devc operation). Note that Java 17 support requires Gradle v7.3 or greater.

Language Server Debug

Liberty LS

To debug lemminx, start the hosting Eclipse with JVM sysprop like: -Dorg.eclipse.wildwebdeveloper.xml.internal.XMLLanguageServer.debugPort=8000 (from[…]rg/eclipse/wildwebdeveloper/xml/internal/

MicroProfile LS

To debug MicroProfile LS , start the hosting Eclipse with JVM sysprop like:

Preparing new version

mvn org.eclipse.tycho:tycho-versions-plugin:2.7.0:set-version -DnewVersion=0.2.0-SNAPSHOT (e.g.

⚠️ ** Fallback** ⚠️