Dockerfile,Makefile: add dockershell Makefile target for Docker builds

Fixes tailscale/tailscale#424

Signed-off-by: Elias Naur <mail@eliasnaur.com>

Dockerfile

@@ -1,5 +1,5 @@
-# This is the start of a Dockerfile to build tailscale-android.
-# It works, but it's not very efficient yet; see TODOs below.
+# This is a Dockerfile for creating a build environment for
+# tailscale-android.
 
 FROM openjdk:8-jdk
 
@@ -10,6 +10,8 @@ RUN apt-get install -y lib32z1 lib32stdc++6
 RUN apt-get -y --no-install-recommends install curl gcc
 RUN apt-get -y --no-install-recommends install ca-certificates libc6-dev git
 
+RUN apt-get -y install make
+
 RUN mkdir -p BUILD
 ENV HOME /build
 
@@ -35,7 +37,7 @@ RUN curl -O https://storage.googleapis.com/golang/go${GO_VERSION}.linux-amd64.ta
 RUN echo "1c39eac4ae95781b066c144c58e45d6859652247f7515f0d2cba7be7d57d2226  go${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
+ENV PATH $PATH:$GOROOT/bin:$HOME/bin:$ANDROID_HOME/platform-tools
 
 RUN mkdir -p $HOME/tailscale-android
 WORKDIR $HOME/tailscale-android
@@ -49,6 +51,4 @@ COPY android/gradlew android/gradlew
 COPY android/gradle android/gradle
 RUN ./android/gradlew
 
-ADD . .
-RUN ./build.sh
-
+CMD /bin/bash

Makefile

@@ -25,7 +25,11 @@ release: $(RELEASE_AAB)
 install: $(DEBUG_APK)
 	adb install -r $(DEBUG_APK)
 
+dockershell:
+	docker build -t tailscale-android .
+	docker run -v $(CURDIR):/build/tailscale-android -it --rm tailscale-android
+
 clean:
 	rm -rf android/build $(RELEASE_AAB) $(DEBUG_APK) $(AAR)
 
-.PHONY: all clean install aar release
+.PHONY: all clean install aar release dockershell

README.md

@@ -23,6 +23,14 @@ $ make tailscale-debug.apk
 $ adb install -r tailscale-debug.apk
 ```
 
+The `dockershell` target builds a container with the necessary
+dependencies and runs a shell inside it.
+
+```
+$ make dockershell
+# make tailscale-debug.apk
+```
+
 We only guarantee to support the latest Go release and any Go beta or
 release candidate builds (currently Go 1.14) in module mode. It might
 work in earlier Go versions or in GOPATH mode, but we're making no

build.sh

@@ -1,10 +0,0 @@
-#!/bin/sh
-# Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
-# Use of this source code is governed by a BSD-style
-# license that can be found in the LICENSE file.
-
-set -e
-
-mkdir -p android/libs
-go run gioui.org/cmd/gogio -buildmode archive -target android -appid com.tailscale.ipn -o android/libs/ipn.aar tailscale.com/tailscale-android/cmd/tailscale
-(cd android && ./gradlew assembleDebug)