Error: Timeout waiting for emulator to boot caused by insufficient disk space

[marcprux]

When using the swift-android-action to run Swift tests cases against the Android emulator, you may sometimes encounter the error:

Error: Timeout waiting for emulator to boot.

Most of the time, the real issue is that the emulator startup process immediately failed due to not having enough disk space to create the emulator. This can be confirmed by expanding the "Launch Emulator" section in the actions log, which may look like:

  INFO         | Guest GLES Driver: Auto (ext controls)
  WARNING      | Your GPU drivers may have a bug. Switching to software rendering.
  library_mode swangle_indirect gpu mode swangle_indirect
  INFO         | Checking system compatibility:
  INFO         |   Checking: hasSufficientDiskSpace
  INFO         |      Ok: Disk space requirements to run avd: `test` are met
  INFO         |   Checking: hasSufficientHwGpu
  INFO         |      Ok: Hardware GPU compatibility checks are not required
  INFO         |   Checking: hasSufficientSystem
  INFO         |      Ok: System requirements to run avd: `test` are met
  FATAL        | Not enough space to create userdata partition. Available: 6791.23 MB at /home/runner/.android/avd/test.avd, need 7372.80 MB.

It is this last FATAL error that causes the emulator to fail to start, but because we do not start the emulator in the foreground, we only identify a failure to start via a timeout waiting for it to become responsive.

We should do some better (and more immediate) diagnostics to at least report to the user that this is the problem and advise them to free up disk space.

Note that this can happen for any number of reasons (e.g., because prior actions are doing things that take up a lot of disk space), but it has recently become a more frequent occurrence due to the the stock ubuntu-latest and macos-latest actions runners becoming more loaded down with pre-installed (and usually unnecessary) software, reducing the amount of free space they have out of the box.

The solution is to free up some disk space, either using an action like https://github.com/marketplace/actions/free-disk-space-ubuntu, or just manually adding a step to your workflow like the one in this workflow's README:

jobs:
  linux-android:
    runs-on: ubuntu-latest
    steps:
      # Ubuntu runners can run low on space can cause the emulator to fail to install
      - name: "Free Disk Space"
        run: |
          if [[ "${RUNNER_OS}" == "macOS" ]]; then
            sudo rm -rf /Applications/Xcode_1[4567]*.app
          else
            sudo rm -rf /opt/microsoft /opt/google /opt/az /usr/share/miniconda /usr/share/az* /usr/share/glade* /usr/local/share/chromium /usr/local/share/powershell /usr/share/dotnet /opt/ghc /opt/hostedtoolcache/CodeQL /usr/local/share/boost
          fi
          docker image prune --all --force
          docker builder prune -a
      - uses: actions/checkout@v4
      - name: "Test Swift Package on Linux"
        run: swift test
      - name: "Test Swift Package on Android"
        uses: skiptools/swift-android-action@v2

[marcprux]

See also: ReactiveCircus/android-emulator-runner#455

[marcprux]

I've added a free-disk-space: true input parameter to help with this issue, and mention of it in the README.

It would still be nice to correctly report this error condition, so I'll leave this issue open until we can implement detection of the error and proper surfacing of it.