I’m working on a project where we use GitHub Actions to automate our Maven build process. We dynamically set the version number in the format projectversion-runID-runNumber, like 8.1.0-9761957358-18. We include that runID in the build version so the deploy workflow can parse it out and download artifacts from the build workflow.

In our build workflow, we use mvn versions:set to update the versions. However, the command is failing with a “relative path” error specifically for the submodules which refer to the module poms as parents with ../../pom.xml. The pom files of those modules, which refer to the parent pom with ../pom.xml, seem to have no problem. Here are the details:

Error Message:

[ERROR] Child module ... of ... cannot be found in the workspace
[ERROR] The POM for ... is missing, no dependency information available
[FATAL] Non-resolvable parent POM for com.example.project.submodule: Could not find artifact com.example.project:module:pom:8.1.0-9761957358-18 in central (https://repo1.maven.org/maven2) and 'parent.relativePath' points at wrong local POM

File Structure:

project-root/
│
├── parent-pom.xml
├── module1/
│   ├── pom.xml
│   └── modules/
│       ├── submodule1/
│       │   └── pom.xml
│       ├── submodule2/
│       │   └── pom.xml

Workflow Steps:

name: Build and Publish

on:
  push:
    paths-ignore: ['.github/**']
  workflow_dispatch:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Repo
        uses: actions/checkout@v4

      - name: Set Up JDK 11
        uses: actions/setup-java@v4
        with:
          java-version: 11
          distribution: 'temurin'
          cache: maven

      - name: Set Version
        run: |
          mvn versions:set -DnewVersion=8.1.0-${{ github.run_id }}-${{ github.run_number }} -DgenerateBackupPoms=false

I’ve verified that the POM files do exist in the local repository, which I believe is the first place Maven looks. We incorporate the runID into the build version so we can parse out the run ID from the tag we create from it. This lets the GitHub deploy workflow download artifacts created from the build workflow.

POM File Examples:

Parent POM (parent-pom.xml):

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.example.project</groupId>
  <artifactId>parent-project</artifactId>
  <version>8.1.0</version>
  <packaging>pom</packaging>
  <modules>
    <module>module1</module>
  </modules>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>
</project>
Module POM (module1/pom.xml):

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <parent>
    <artifactId>parent-project</artifactId>
    <groupId>com.example.project</groupId>
    <version>8.1.0</version>
    <relativePath>../parent-pom.xml</relativePath>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.example.project.module1</groupId>
  <artifactId>module1</artifactId>
  <packaging>pom</packaging>
  <modules>
    <module>modules/submodule1</module>
  </modules>
</project>
Submodule POM (module1/modules/submodule1/pom.xml):

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <parent>
    <artifactId>module1</artifactId>
    <groupId>com.example.project.module1</groupId>
    <version>8.1.0</version>
    <relativePath>../../pom.xml</relativePath>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.example.project.module1</groupId>
  <artifactId>submodule1</artifactId>
  <packaging>jar</packaging>
</project>

Thinks I’ve tried:

• Replacing the versions:set command with mvn dependency:tree
  and encountered the same “relative path” error.
• Adding an rm -rf of the github action runner’s local maven repo, to
  make sure the maven cache was cleared, and it didn’t help.
• Taking out the runID in the build version numbers. Same problem.
• Individually installing all the poms explicitly, with
  mvn install -N for each module. No dice.
• Doublechecked that the groupIds and artifactIds, and versions listed in
  the parent sections matched what was in the parent pom.xml referred to.
• This workflow did run somehow before, but then someone did a merge one
  day and all the builds started failing this way. I’m wondering if it was
  maybe accessing something cached, but not sure how.

Any insights on how to resolve this issue would be greatly appreciated!