Start of a Dockerfile.

It can be improved a lot to be more incremental, but this is something for now.

Updates tailscale/tailscale#424

Dockerfile

@@ -0,0 +1,68 @@
+# This is the start of a Dockerfile to build tailscale-android.
+# It works, but it's not very efficient yet; see TODOs below.
+
+FROM openjdk:8-jdk
+
+# To enable running android tools such as aapt
+RUN apt-get update && apt-get -y upgrade
+RUN apt-get install -y lib32z1 lib32stdc++6
+# For Go:
+RUN apt-get -y --no-install-recommends install curl gcc
+RUN apt-get -y --no-install-recommends install ca-certificates libc6-dev git
+
+RUN mkdir -p BUILD
+ENV HOME /build
+
+# Get android sdk, ndk, and rest of the stuff needed to build the android app.
+WORKDIR $HOME
+RUN mkdir android-sdk
+ENV ANDROID_HOME $HOME/android-sdk
+WORKDIR $ANDROID_HOME
+RUN curl -O https://dl.google.com/android/repository/sdk-tools-linux-3859397.zip
+RUN echo '444e22ce8ca0f67353bda4b85175ed3731cae3ffa695ca18119cbacef1c1bea0  sdk-tools-linux-3859397.zip' | sha256sum -c
+RUN unzip sdk-tools-linux-3859397.zip
+RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager --update
+RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'platforms;android-29'
+RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'build-tools;29.0.0'
+RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'extras;android;m2repository'
+RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'ndk-bundle'
+
+# Get Go stable release
+WORKDIR $HOME
+ARG GO_VERSION=1.14.3
+RUN curl -O https://storage.googleapis.com/golang/go${GO_VERSION}.linux-amd64.tar.gz
+RUN echo "1c39eac4ae95781b066c144c58e45d6859652247f7515f0d2cba7be7d57d2226  go${GO_VERSION}.linux-amd64.tar.gz" | sha256sum -c
+RUN tar -xzf go${GO_VERSION}.linux-amd64.tar.gz && mv go goroot
+ENV GOROOT $HOME/goroot
+ENV PATH $PATH:$GOROOT/bin:$HOME/bin
+
+RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'platforms;android-26'
+RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'ndk;20.1.5948944'
+RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'ndk;20.0.5594570'
+
+# TODO: pre-install Grade 6.3 so gogio doesn't download it later at runtime at the build.sh step.
+# TODO: ... likewise, all this:
+# Checking the license for package Android SDK Build-Tools 28.0.3 in /build/android-sdk/licenses
+# License for package Android SDK Build-Tools 28.0.3 accepted.
+# Preparing "Install Android SDK Build-Tools 28.0.3 (revision: 28.0.3)".
+# "Install Android SDK Build-Tools 28.0.3 (revision: 28.0.3)" ready.
+# Installing Android SDK Build-Tools 28.0.3 in /build/android-sdk/build-tools/28.0.3
+# "Install Android SDK Build-Tools 28.0.3 (revision: 28.0.3)" complete.
+# "Install Android SDK Build-Tools 28.0.3 (revision: 28.0.3)" finished.
+# Checking the license for package Android SDK Platform-Tools in /build/android-sdk/licenses
+# License for package Android SDK Platform-Tools accepted.
+# Preparing "Install Android SDK Platform-Tools (revision: 30.0.1)".
+# "Install Android SDK Platform-Tools (revision: 30.0.1)" ready.
+# Installing Android SDK Platform-Tools in /build/android-sdk/platform-tools
+# "Install Android SDK Platform-Tools (revision: 30.0.1)" complete.
+# "Install Android SDK Platform-Tools (revision: 30.0.1)" finished.
+
+RUN mkdir -p $HOME/tailscale-android
+WORKDIR $HOME/tailscale-android
+
+ADD go.mod .
+ADD go.sum .
+RUN go mod download
+ADD . .
+RUN ./build.sh
+