Android support for Dependency Scanning (gemnasium-maven)

Release notes

TODO: Announce Android support for Dependency Scanning

Problem to solve

GitLab Dependency Scanning supports Java Gradle projects but Android projects aren't supported because:

The Android SDK isn't installed in the gemnasium-maven image used for the scan.
There's no documentation on how to set up Dependency Scanning for Android projects.
The possible workaround are too tied to implementation details of gemnasium-maven.

Intended users

User experience goal

Setup and usage are similar to Dependency Scanning for any Java Gradle project.

Proposal

We can either:

Pre-install the Android SDK in the gemnasium-maven
Pre-install Android's sdkmanager and allow users to select which android tools version they want to use via the two platform and build options (see workaround section below). This can be done by introducing two new DS variables: e.g. DS_ANDROID_SDK_PLATFORM and DS_ANDROID_SDK_BUILD_TOOLS
Make it easy to run Java commands prior to the scan
Parse the output of the androidDependencies task (or app:dependencies if app is the main module), similar to what's been proposed in Replace gemnasium-gradle-plugin with the htmlDe... (#337083)
Parse the root.js files created by the htmlDependencyReport task, as proposed in #337083

Questions:

Which versions of the Android should be pre-installed in the image?
Should we make it easy to switch between versions using a new CI variable?

Further details

This CI configuration shared by @sabinecarpenter seems to work:

gemnasium-maven-dependency_scanning:
  variables:
    ANDROID_SDK_ROOT: "/path/to/android_sdk_root"
    SECURE_LOG_LEVEL: debug
    ANDROID_COMPILE_SDK: "29"
    ANDROID_BUILD_TOOLS: "29.0.3"
    ANDROID_SDK_TOOLS: "6514223"
  before_script:
    - export ASDF_DATA_DIR="/opt/asdf"
    - . $HOME/.bashrc
    - switch_to java "adoptopenjdk-${DS_JAVA_VERSION:-11}"
    - # commands to install Android dependencies...
  script:
    - /analyzer run

This CI configuration shared by @ifrenkel seems to work:

prep android sdk:
  image: registry.gitlab.com/gitlab-org/security-products/analyzers/gemnasium-maven:2 # analyzer image has needed java but another java docker img can work as well
  stage: pre-test
  script:
    - source ~/.bashrc # ensure java available to commands below
    - apt-get update && apt-get install -y wget
    - mkdir /tmp/sdktools
    - wget $COMMAND_LINE_TOOLS_ARCHIVE -O /tmp/sdktools/tools.zip # install sdkmanager
    - unzip /tmp/sdktools/tools.zip -d /tmp/sdktools/
    - mkdir .prepped-android-sdk
    - echo yes > answer # can't pipe yes to command below
    - /tmp/sdktools/cmdline-tools/bin/sdkmanager --verbose --sdk_root=.prepped-android-sdk "platform-tools" "$ANDROID_SDK_PLATFORM" < answer
    - /tmp/sdktools/cmdline-tools/bin/sdkmanager --verbose --sdk_root=.prepped-android-sdk "$BUILD_TOOLS" < answer

These could be documented workarounds but:

They are fairly complex.
They leak implementation details, in particular the existing of a /root/.bashrc Shell script to be source before running any command.