GitHub Actions: Cache Maven .m2 repository on Windows environment C\:\\Users\runneradmin\\.m2\repository: Cannot stat: No such file or directory

Question

As the docs state in order to cache the Maven dependencies with GitHub Actions all we have to use is the actions/cache action like this:

steps:
  - uses: actions/checkout@v2
  - name: Set up JDK 1.8
    uses: actions/setup-java@v1
    with:
      java-version: 1.8
  - name: Cache Maven packages
    uses: actions/cache@v2
    with:
      path: ~/.m2
      key: ${{ runner.os }}-m2-${{ hashFiles('**/pom.xml') }}
      restore-keys: ${{ runner.os }}-m2
  - name: Build with Maven
    run: mvn --batch-mode --update-snapshots verify

However using the windows-2016 GitHub Actions environment, this doesn't provides us with a working cache - as the logs states :

Post job cleanup.
"C:\Program Files\Git\usr\bin\tar.exe" --posix --use-compress-program "zstd -T0" -cf cache.tzst -P -C D:/a/spring-boot-admin/spring-boot-admin --files-from manifest.txt --force-local
/usr/bin/tar: C\:\\Users\runneradmin\\.m2\repository: Cannot stat: No such file or directory
/usr/bin/tar: Exiting with failure status due to previous errors
Warning: Tar failed with error: The process 'C:\Program Files\Git\usr\bin\tar.exe' failed with exit code 2

How to fix this?

Answer 1

It seems that the path to the Maven repository isn't correctly initialized. As this issue describes the paths are written with \\ instead of / which GNU tar expects. The fix was already provided in Dec 2020 , so it made it to the version v2.1.4 . The last version v2.1.3 was released in November. But sadly there is a bug in pointing the v2 to the latest v2.1.4 (as normally expected by GitHub Actions users). Therefore to solve this issue, we need to explicitely specifiy the full actions/cache version v2.1.4 like this:

steps:
  - uses: actions/checkout@v2
  - name: Set up JDK 1.8
    uses: actions/setup-java@v1
    with:
      java-version: 1.8
  - name: Cache Maven packages
    uses: actions/cache@v2.1.4
    with:
      path: ~/.m2
      key: ${{ runner.os }}-m2-${{ hashFiles('**/pom.xml') }}
      restore-keys: ${{ runner.os }}-m2
  - name: Build with Maven
    run: mvn --batch-mode --update-snapshots verify

Now it should work like a charm ( see logs here ).