Adding a top level Dockerfile and hooks for providing build args.

  * As per docker/hub-feedback#508,
    there is no way to specify build_args to Docker builds on docker
    hub. The only solution is to have hack using hooks.

    This works but for different variants, there will be too many
    different environment variables to be defined.

Dockerfile

@@ -0,0 +1,68 @@
+ARG OPENJDK_VERSION="14"
+
+FROM openjdk:${OPENJDK_VERSION}-slim
+LABEL maintainer Divick K.<divick@gorapid.io>
+
+ARG CMDLINE_TOOLS_VERSION
+ARG BUILD_TOOLS
+ARG TARGET_SDK
+ARG ANDROID_HOME
+ARG RUBY_VERSION
+ARG FASTLANE_VERSION
+
+# Check if the build args to docker build have been passed or not
+RUN test -n "$CMDLINE_TOOLS_VERSION"
+RUN test -n "$BUILD_TOOLS"
+RUN test -n "$TARGET_SDK"
+RUN test -n "$ANDROID_HOME"
+RUN test -n "$RUBY_VERSION"
+RUN test -n "$FASTLANE_VERSION"
+
+# Specify the environment variables (which are available inside the
+# container when using `docker run` command) as well as during the
+# `docker build` command
+ENV CMDLINE_TOOLS_VERSION="${CMDLINE_TOOLS_VERSION}" \
+    BUILD_TOOLS="${BUILD_TOOLS}" \
+    TARGET_SDK="${TARGET_SDK}" \
+    ANDROID_HOME="${ANDROID_HOME}" \
+    RUBY_VERSION="${RUBY_VERSION}" \
+    PATH=/root/.rbenv/shims:/root/.rbenv/bin:/root/.rbenv/plugins/ruby-build/bin:$PATH
+
+# 1. Install required dependencies via apt
+# 2. Download and extract Android android sdk and tools
+# 3. Install rbenv to install required ruby version
+# 4. Install ruby
+# 5. Install fastlane
+RUN apt-get update \
+    && apt-get install -y \
+        ca-certificates \
+        libssl-dev \
+        libreadline-dev \
+        zlib1g-dev \
+        gcc \
+        g++ \
+        make \
+        wget \
+        unzip \
+        bzip2 \
+        git \
+    && rm -rf /var/cache/apt/* \
+    && rm -rf /var/lib/apt/lists/* \
+    && wget https://dl.google.com/android/repository/commandlinetools-linux-${CMDLINE_TOOLS_VERSION}_latest.zip -O /tmp/tools.zip \
+    && mkdir -p ${ANDROID_HOME} \
+    && unzip /tmp/tools.zip -d ${ANDROID_HOME} \
+    && rm -v /tmp/tools.zip \
+    && mkdir -p /root/.android/ \
+    && touch /root/.android/repositories.cfg \
+    && yes | ${ANDROID_HOME}/tools/bin/sdkmanager --sdk_root=${ANDROID_HOME} "--licenses" \
+    && ${ANDROID_HOME}/tools/bin/sdkmanager --sdk_root=${ANDROID_HOME} "--update" \
+    && ${ANDROID_HOME}/tools/bin/sdkmanager --sdk_root=${ANDROID_HOME} "build-tools;${BUILD_TOOLS}" "platform-tools" "platforms;android-${TARGET_SDK}" "extras;android;m2repository" "extras;google;google_play_services" "extras;google;m2repository" "emulator" \
+    && git clone https://github.com/rbenv/rbenv.git ~/.rbenv \
+    && git clone https://github.com/rbenv/ruby-build.git "$(rbenv root)"/plugins/ruby-build \
+    && echo 'eval "$(rbenv init -)"' >> /etc/profile.d/rbenv.sh \
+    && echo 'eval "$(rbenv init -)"' >> /root/.bashrc \
+    && mkdir -p "$(rbenv root)"/plugins \
+    && rbenv install ${RUBY_VERSION} \
+    && rbenv global ${RUBY_VERSION} \
+    && gem install bundler \
+    && gem install fastlane -v ${FASTLANE_VERSION}

hooks/build

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+docker build \
+    --build-arg CMDLINE_TOOLS_VERSION=$CMDLINE_TOOLS_VERSION \
+    --build-arg OPENJDK_VERSION=$OPENJDK_VERSION \
+    --build-arg BUILD_TOOLS=$BUILD_TOOLS \
+    --build-arg TARGET_SDK=$TARGET_SDK \
+    --build-arg ANDROID_HOME=$ANDROID_HOME \
+    --build-arg RUBY_VERSION=$RUBY_VERSION \
+    --build-arg FASTLANE_VERSION=$FASTLANE_VERSION \
+    -f $DOCKERFILE_PATH -t $IMAGE_NAME .