Connect to Android Emulator in a Docker Container

I'm using a VNC client (Remmina) to connect to an Android Emulator running in a Docker container, and it worked with APIs from 19 to 27, but 28 errors when using with the VNC option (but works without VNC):

qemu-system-x86_64: VNC supports only guest GPU, add "-gpu guest" option

My environment:

myrepo/app-tools:android-dev-1.0.2

FROM ubuntu:18.04

ENV DEBIAN_FRONTEND noninteractive
RUN echo "debconf shared/accepted-oracle-license-v1-1 select true" | debconf-set-selections && \
    echo "debconf shared/accepted-oracle-license-v1-1 seen true" | debconf-set-selections

ENV SDK_URL="https://dl.google.com/android/repository/sdk-tools-linux-4333796.zip" \
    ANDROID_HOME="/usr/local/android-sdk" \
    ANDROID_VERSION="28" \
    ANDROID_BUILD_TOOLS_VERSION="28.0.3" \
    GRADLE_VERSION="5.0"
ENV GRADLE_URL="https://services.gradle.org/distributions/gradle-${GRADLE_VERSION}-bin.zip" \
    GRADLE_HOME="/opt/gradle/gradle-${GRADLE_VERSION}" \
    PATH="/opt/gradle/gradle-${GRADLE_VERSION}/bin:${PATH}:${ANDROID_HOME}/tools:${ANDROID_HOME}/tools/bin:${ANDROID_HOME}/platform-tools"

COPY android/repositories.cfg /root/.android/

# Download JDK-8 and fix certificate issues
RUN apt-get update \ 
 && apt-get install -y openjdk-8-jdk \
 && apt-get install -y ant \
 && apt-get clean \
 && rm -rf /var/lib/apt/lists/* \
 && rm -rf /var/cache/oracle-jdk8-installer \
 && apt-get update \ 
 && apt-get install -y ca-certificates-java \
 && apt-get clean \
 && update-ca-certificates -f \
 && rm -rf /var/lib/apt/lists/* \
 && rm -rf /var/cache/oracle-jdk8-installer

# Download Android SDK
RUN cd /tmp \
 && apt-get update \
 && apt-get install -y nano zip curl net-tools socat \
 && curl -o gradle.zip -L "$GRADLE_URL" \
 && unzip -d /opt/gradle gradle.zip \
 && rm gradle.zip \
 && mkdir "$ANDROID_HOME" .android \
 && cd "$ANDROID_HOME" \
 && curl -o sdk.zip $SDK_URL \
 && unzip sdk.zip \
 && rm sdk.zip \
 && yes | "$ANDROID_HOME/tools/bin/sdkmanager" --licenses \
 && "$ANDROID_HOME/tools/bin/sdkmanager" --update \
 && "$ANDROID_HOME/tools/bin/sdkmanager" \
    "build-tools;${ANDROID_BUILD_TOOLS_VERSION}" \
    "platforms;android-${ANDROID_VERSION}" \
    "platform-tools" \
    "emulator"

RUN mkdir /main
WORKDIR /main

android/repositories.cfg

### User Sources for Android SDK Manager
#Fri Nov 03 10:11:27 CET 2017 count=0

android-dev.dockerfile

FROM myrepo/app-tools:android-dev-1.0.2

ENV ANDROID_SDK="/usr/local/android-sdk"
ENV PATH="$ANDROID_SDK/emulator:$ANDROID_SDK/tools:$PATH"

RUN /usr/local/android-sdk/tools/bin/sdkmanager "system-images;android-19;google_apis;x86" \
 && /usr/local/android-sdk/tools/bin/sdkmanager --licenses

RUN /usr/local/android-sdk/tools/bin/sdkmanager "system-images;android-23;google_apis;x86" \
 && /usr/local/android-sdk/tools/bin/sdkmanager --licenses

RUN /usr/local/android-sdk/tools/bin/sdkmanager "system-images;android-28;google_apis;x86" \
 && /usr/local/android-sdk/tools/bin/sdkmanager --licenses

RUN /usr/local/android-sdk/tools/bin/avdmanager create avd -n avd19 -k "system-images;android-19;google_apis;x86" -b x86 -d 7 -f \
 && /usr/local/android-sdk/tools/bin/avdmanager create avd -n avd23 -k "system-images;android-23;google_apis;x86" -b x86 -d 7 -f \
 && /usr/local/android-sdk/tools/bin/avdmanager create avd -n avd28 -k "system-images;android-28;google_apis;x86" -b x86 -d 7 -f

COPY scripts/android-dev-startup.sh /root/start.sh

scripts/android-dev-startup.sh

#!/bin/bash
set -eou pipefail

socat tcp-listen:5037,bind=android-dev,fork tcp:127.0.0.1:5037 &
socat tcp-listen:5554,bind=android-dev,fork tcp:127.0.0.1:5554 &
socat tcp-listen:5555,bind=android-dev,fork tcp:127.0.0.1:5555 &

sleep infinity

docker-compose

android-dev:
  build: 
    context: ./
    dockerfile: android-dev.dockerfile
  hostname: android-dev
  volumes:
  - .:/main:rw
  devices:
  - "/dev/kvm:/dev/kvm"
  ports:
  - "5037:5037"
  - "5554:5554"
  - "5555:5555"
  - "5900:5900"
  command: /root/start.sh

Then, if I run the command to start the emulator, it works in all cases except when using the emulator with android-28 (when using VNC):

# works
emulator -memory 4096 -avd avd19 -noaudio -no-window -gpu off -verbose -qemu -vnc :0

# works
emulator -memory 4096 -avd avd23 -noaudio -no-window -gpu off -verbose -qemu -vnc :0

# works
emulator -memory 4096 -avd avd28 -noaudio -no-window -gpu off -verbose -qemu

# doesn't work
# qemu-system-x86_64: VNC supports only guest GPU, add "-gpu guest" option
emulator -memory 4096 -avd avd28 -noaudio -no-window -gpu off -verbose -qemu -vnc :0

# doesn't work
# qemu-system-x86_64: VNC supports only guest GPU, add "-gpu guest" option
emulator -memory 4096 -avd avd28 -noaudio -no-window -gpu guest -verbose -qemu -vnc :0

I think the error comes from this file:

https://android.googlesource.com/platform/external/qemu/+/emu-master-dev/vl.c

Is there a way to make it work with VNC?

I found something interesting in the output of the emulator-headless:

emulator: WARNING: Your AVD has been configured with an in-guest renderer, but the system image does not support guest rendering.Falling back to 'swiftshader_indirect' mode.
emulator: GPU emulation enabled using 'swiftshader_indirect' mode
emulator: Initializing hardware OpenGLES emulation support

https://androidstudio.googleblog.com/2018/11/emulator-28016-stable.html?m=1

-gpu guest (software rendering in the guest) has been deprecated. API 28+ system images will now auto switch to using Swiftshader (-gpu swiftshader_indirect).

So it switches to swiftshader_indirect, which makes it unable to use vnc. Uh oh.

So now I wonder if one can use environmental variable DISPLAY to make emulator-headless render the graphics into virtual display that one will create with some another VNC server...

Edit: Yes, it seems to be working well on 2 Xeon cores 3.3Ghz each and 4GB RAM.

echo 'no' | avdmanager create avd --force --name android-28-x86 --abi google_apis_playstore/x86 --package 'system-images;android-28;google_apis_playstore;x86'

apt install tightvnc
apt install xfonts-base
sudo apt-get install gnome-core xfce4 firefox nano -y --force-yes

# ~/.vnc/xstatup
unset SESSION_MANAGER unset DBUS_SESSION_BUS_ADDRESS startxfce4 & [ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup [ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources xsetroot -solid grey vncconfig -iconic &

vncserver :2 -geometry 1080x1920 -depth 24
export DISPLAY=:2.0
emulator @android-28-x86 -verbose -memory 2048 -gpu swiftshader_indirect -no-audio -no-snapshot -wipe-data -no-boot-anim -skin 768x1280

I still have no idea why the android emulator developers decided to disable vnc support in their product if everything works well with gpu software emulation on standalone vnc server..?

Edit2: It always loads CPU 100% though. Apparently it requires a fix. https://gist.github.com/yazinsai/652f0e6e77c9594a2356dd6314a9c3d8 LMK if you want to implement it.