Gitlab CI pipeline setup to build android apps.

.gitlab-ci.yml

image: registry.gitlab.com/username/project_name:latest

stages:
  - build

before_script:
  - export GRADLE_USER_HOME=$(pwd)/.gradle
  - chmod +x ./gradlew

cache:
  key: ${CI_PROJECT_ID}
  paths:
    - .gradle/

build:
  stage: build
  script:
    - ./gradlew assembleDebug
  artifacts:
    paths:
      - app/build/outputs/apk/debug/app-debug.apk

build_docker_image.sh

#!/usr/bin/env bash

docker build -t registry.gitlab.com/username/project_name . && docker push registry.gitlab.com/username/project_name

Dockerfile

FROM openjdk:8-alpine

ENV BUILD_TOOLS "29.0.2"
ENV SDK_TOOLS_API "29"

ENV ANDROID_HOME "/opt/sdk"
ENV GLIBC_VERSION "2.27-r0" 

# Install required dependencies
RUN apk add --no-cache --virtual=.build-dependencies wget unzip ca-certificates bash && \
  wget https://alpine-pkgs.sgerrand.com/sgerrand.rsa.pub -O /etc/apk/keys/sgerrand.rsa.pub && \
  wget https://github.com/sgerrand/alpine-pkg-glibc/releases/download/${GLIBC_VERSION}/glibc-${GLIBC_VERSION}.apk -O /tmp/glibc.apk && \
  wget https://github.com/sgerrand/alpine-pkg-glibc/releases/download/${GLIBC_VERSION}/glibc-bin-${GLIBC_VERSION}.apk -O /tmp/glibc-bin.apk && \
  apk add --no-cache /tmp/glibc.apk /tmp/glibc-bin.apk && \
  rm -rf /tmp/*

# Download Android SDK tools
RUN wget http://dl.google.com/android/repository/sdk-tools-linux-3859397.zip -O /tmp/tools.zip && \
  mkdir -p ${ANDROID_HOME} && \
  unzip /tmp/tools.zip -d ${ANDROID_HOME} && \
  rm -v /tmp/tools.zip

# Install Android packages & libraries
RUN export PATH=$PATH:$ANDROID_HOME/tools/bin && \
  mkdir -p /root/.android/ && touch /root/.android/repositories.cfg && \
  yes | sdkmanager "--licenses" && \
  sdkmanager --verbose "build-tools;${BUILD_TOOLS}" "platform-tools" "platforms;android-${SDK_TOOLS_API}" \
  && sdkmanager --verbose "extras;android;m2repository" "extras;google;google_play_services" "extras;google;m2repository"

# Install git
RUN apk add --no-cache git