Android SDK on Docker for ARM64 (Raspberry Pi 4) for building APK

I am trying to create an ARM64 Docker image which is able to build an apk file of my React Native app.

Background:

For exercise purposes I built a Kubernetes cluster wiht 5 Raspberry Pi 4 boards. Everything is working fine, Jenkins is running on it and the backend part (Java Microservice, Maven) can be built, deployed and run on it.

Now I am trying to create a Pipeline for the Android App part, which I build in React Native, Gradle. I'm just learning how everything fits together and am stuck with building the apk file on Jenkins. Locally building it (on Linux) is working fine but I'm not able to create a Docker container for the aarch64 architecture with the necessary Android SDK stuff installed to build it with Jenkins. Here is what I have by now (tell me, if I have to provide more information!):

Dockerfile:

FROM openjdk:8-alpine3.9

ENV ANDROID_SDK_ROOT /opt/android-sdk-linux

RUN apk add --no-cache curl wget bash unzip \
    && apk add --no-cache --update nodejs npm \
    && npm install -g react-native-cli

RUN cd /opt \
    && wget -q https://dl.google.com/android/repository/commandlinetools-linux-6609375_latest.zip -O android-commandline-tools.zip \
    && mkdir -p ${ANDROID_SDK_ROOT}/cmdline-tools \
    && unzip -q android-commandline-tools.zip -d ${ANDROID_SDK_ROOT}/cmdline-tools \
    && rm android-commandline-tools.zip

ENV PATH ${PATH}:${ANDROID_SDK_ROOT}/platform-tools:${ANDROID_SDK_ROOT}/cmdline-tools/tools/bin

RUN yes | sdkmanager --licenses

RUN touch /root/.android/repositories.cfg

# This part fails!
# RUN yes | sdkmanager "emulator" "platform-tools"

RUN yes | sdkmanager --update --channel=3
RUN yes | sdkmanager \
    "platforms;android-29" \
    "build-tools;29.0.3" \
    "build-tools;29.0.2" \
    "build-tools;29.0.1" \
    "build-tools;29.0.0"

Jenkinsfile:

pipeline {
    agent {
        kubernetes {
            defaultContainer 'app-build'
            yamlFile 'kubernetes-pod.yaml'
        }
    }
    stages {
        stage ('print env vars') {
            steps {
                sh 'printenv'
                sh 'echo "JAVA-VERSION: "'
                sh 'java -version'
                sh 'echo "NODE-VERSION:"'
                sh 'node --version'
                sh 'echo "NPM version:" '
                sh 'npm --version'
                sh 'echo "REACT-NATIVE-VERSION:"'
                sh 'react-native --version'
            }
        }
       stage ('Gradle Build') {
           steps {
               sh ('react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res')
               dir ('android') {
                   // this step fails (error message below)
                   gradlew('assembleRelease', '--scan')
               }
           }
       }

       /* ... more steps ... */
    }
}

def gradlew(String... args) {
    sh "./gradlew ${args.join(' ')} -s"
}

The error message I get on Jenkins is the following:

Starting a Gradle Daemon (subsequent builds will be faster)

> Configure project :react-native-reanimated
Warning: Dependant package with key emulator not found!

FAILURE: Build failed with an exception.

* Where:
Build file '/home/jenkins/agent/workspace/nches_CHEF-8-frontend-deployment/node_modules/react-native-reanimated/android/build.gradle' line: 89

* What went wrong:
A problem occurred configuring project ':react-native-reanimated'.
> Failed to install the following SDK components:
      build-tools;29.0.2 Android SDK Build-Tools 29.0.2
  Install the missing components using the SDK manager in Android Studio.

I would be very happy if someone could help me solving this problem, that so I can attack the next obstacles, which I guess would be copying the generated apk into another Docker image and deploy it on the cluster to make it downloadable...

from Android SDK on Docker for ARM64 (Raspberry Pi 4) for building APK