Support for Alpine Linux

This adds support for building a musl flavored J2V8 version, by providing a Alpine dockerfile to cross-compile J2V8 inside.

Also fixes install.maven.sh in case install.java.sh was not run beforehand (opt folder creation)

CMakeLists.txt

@@ -46,6 +46,15 @@ elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
     set(J2V8_LIB_PLATFORM_NAME "linux")
     set(J2V8_LIB_PREFIX "")
     set(J2V8_LIB_ARCH_NAME "x86")
+
+    # TODO: This hack could be used to have a different lib filename for alpine, e.g. libj2v8_alpine_x86_64
+    # However, this would require java code changes to account for the different filename
+    # Source: https://github.com/dotnet/coreclr/pull/5731/files
+    #EXEC_PROGRAM(uname ARGS -v OUTPUT_VARIABLE CMAKE_SYSTEM_KERNEL_VERSION)
+    #string(FIND "${CMAKE_SYSTEM_KERNEL_VERSION}" "Alpine" PAL_SYSTEM_ALPINE)
+    #if(PAL_SYSTEM_ALPINE EQUAL -1)
+    #    set(J2V8_LIB_PLATFORM_NAME "alpine")
+    #endif()
 #}
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
 #{

build.py

@@ -10,6 +10,7 @@
 
 from build_system.config_android import android_config
 from build_system.config_linux import linux_config
+from build_system.config_alpine import alpine_config
 from build_system.config_macos import macos_config
 from build_system.config_win32 import win32_config
 
@@ -34,6 +35,7 @@
 avail_targets = {
     c.target_android: android_config,
     c.target_linux: linux_config,
+    c.target_alpine: alpine_config,
     c.target_macos: macos_config,
     c.target_win32: win32_config,
 }
@@ -53,6 +55,7 @@
                     choices=[
                         c.target_android,
                         c.target_linux,
+                        c.target_alpine,
                         c.target_macos,
                         c.target_win32,
                     ])

build_system/config_alpine.py

@@ -0,0 +1,25 @@
+import constants as c
+from cross_build import BuildStep, PlatformConfig
+from docker_build import DockerBuildSystem
+import config_linux as lc
+
+alpine_config = PlatformConfig(c.target_alpine, [c.arch_x86, c.arch_x64], DockerBuildSystem)
+
+alpine_config.cross_config(BuildStep(
+    name="cross-compile-host",
+    platform=c.target_alpine,
+    host_cwd="$CWD/docker",
+    build_cwd="/j2v8",
+))
+
+alpine_config.set_file_abis({
+    c.arch_x64: "x86_64",
+    c.arch_x86: "x86"
+})
+
+# Alpine build steps are the same as for linux  - just the build environment is different
+alpine_config.build_step(c.build_node_js, lc.build_node_js)
+alpine_config.build_step(c.build_j2v8_cmake, lc.build_j2v8_cmake)
+alpine_config.build_step(c.build_j2v8_jni, lc.build_j2v8_jni)
+alpine_config.build_step(c.build_j2v8_java, lc.build_j2v8_java)
+alpine_config.build_step(c.build_j2v8_junit, lc.build_j2v8_junit)

build_system/constants.py

@@ -1,6 +1,7 @@
 # target platforms
 target_android = 'android'
 target_linux = 'linux'
+target_alpine = 'alpine'
 target_macos = 'macos'
 target_win32 = 'win32'
 

docker/alpine/Dockerfile

@@ -0,0 +1,23 @@
+FROM library/openjdk:8u131-alpine
+
+RUN mkdir -p /temp/docker/shared/
+WORKDIR /temp/docker/shared/
+
+# NOTE: copy shared scripts and run them separately
+# this helps when changing commands only in a single script,
+# since it will not requrie rebuilding all docker image layers
+# but just the ones that were affected
+
+COPY ./shared/install.alpine.packages.sh /temp/docker/shared
+RUN ./install.alpine.packages.sh
+
+COPY ./shared/install.maven.sh /temp/docker/shared
+RUN ./install.maven.sh
+ENV PATH "$PATH:/opt/apache-maven-3.5.0/bin"
+
+# download the most critical maven dependencies for the build beforehand
+COPY ./shared/pom.xml /temp
+WORKDIR /temp
+RUN export J2V8_PLATFORM_NAME=temp && \
+    export J2V8_ARCH_NAME=temp && \
+    mvn verify -DskipTests || true

docker/shared/install.alpine.packages.sh

@@ -0,0 +1,16 @@
+
+echo "Preparing Alpine packages..."
+apk add --update --no-cache \
+	git \
+	unzip \
+	gcc \
+	g++ \
+	curl \
+	file \
+	python \
+	make \
+	cmake \
+	wget \
+	supervisor \
+	bash \
+	linux-headers

docker/shared/install.maven.sh

@@ -1,5 +1,6 @@
 
 echo "Preparing Maven..."
 curl http://www-eu.apache.org/dist/maven/maven-3/3.5.0/binaries/apache-maven-3.5.0-bin.tar.gz -O
+mkdir -p /opt
 tar xzvf apache-maven-3.5.0-bin.tar.gz -C /opt/
 chmod -R 777 /opt/apache-maven-3.5.0