Improve cross compile support

Dockerfile

@@ -0,0 +1,21 @@
+# Image for cross compiling mantle.
+
+FROM ubuntu:17.04
+
+ARG GO_VERSION=1.9.1
+
+RUN apt-get update && apt-get install -y \
+	apt-utils \
+	gcc \
+	gcc-aarch64-linux-gnu \
+	git \
+	wget \
+	&& rm -rf /var/lib/apt/lists/*
+
+RUN wget --no-verbose https://storage.googleapis.com/golang/go${GO_VERSION}.linux-amd64.tar.gz && \
+	tar -C /usr/local -xf go${GO_VERSION}.linux-amd64.tar.gz && \
+	rm go${GO_VERSION}.linux-amd64.tar.gz
+
+ENV PATH /usr/local/go/bin:${PATH}
+
+CMD /bin/bash

Jenkinsfile

@@ -6,26 +6,42 @@ properties([
     [$class: 'CopyArtifactPermissionProperty',
      projectNames: '*'],
 
-    parameters([
-        choice(name: 'GOARCH',
-               choices: "amd64\narm64",
-               description: 'target architecture for building binaries')
-    ]),
-
     pipelineTriggers([pollSCM('H/15 * * * *')])
 ])
 
+def docker_args = "-e CGO_ENABLED=1 --rm -u \"\$(id -u):\$(id -g)\" \
+        -v /etc/passwd:/etc/passwd:ro -v /etc/group:/etc/group:ro -v \"\$PWD\":/usr/src/myapp \
+        -w /usr/src/myapp mantle-builder:1.9.1.0"
+
+def buildMantle = { String targetArch, String targetCC, String extraArgs ->
+    def args = "-e GOARCH=${targetArch} -e CC=${targetCC} ${extraArgs} ${docker_args}"
+    sh "docker run ${args} ./build"
+}
+
+def build_map = [:]
+
+build_map.failFast = false
+build_map['amd64'] = buildMantle.curry('amd64', 'gcc', '')
+build_map['arm64'] = buildMantle.curry('arm64', 'aarch64-linux-gnu-gcc', '-e NO_CROSS=1')
+
 node('amd64 && docker') {
     stage('SCM') {
         checkout scm
     }
 
+    stage('Build Docker') {
+        sh "bash -x ./build-docker --force"
+    }
+
     stage('Build') {
-        sh "docker run --rm -e CGO_ENABLED=1 -e GOARCH=${params.GOARCH} -u \"\$(id -u):\$(id -g)\" -v /etc/passwd:/etc/passwd:ro -v /etc/group:/etc/group:ro -v \"\$PWD\":/usr/src/myapp -w /usr/src/myapp golang:1.9.1 ./build"
+        build_map.each {
+            if (it.value)
+                it.value.call()
+        }
     }
 
     stage('Test') {
-        sh 'docker run --rm -u "$(id -u):$(id -g)" -v /etc/passwd:/etc/passwd:ro -v /etc/group:/etc/group:ro -v "$PWD":/usr/src/myapp -w /usr/src/myapp golang:1.9.1 ./test'
+        sh "docker run ${docker_args} ./test -v"
     }
 
     stage('Post-build') {

build

@@ -17,10 +17,18 @@ ldflags="-X ${REPO_PATH}/version.Version=${version}"
 
 host_build() {
 	echo "Building $1"
-	go build -i -ldflags "${ldflags}" -o "bin/$1" "${REPO_PATH}/cmd/$1"
+
+	if [[ "${GOHOSTARCH}" == "${GOARCH}" ]]; then
+		install_dir="bin"
+	else
+		install_dir="bin/${GOARCH}"
+	fi
+	mkdir -p "${install_dir}"
+	go build -ldflags "${ldflags}" -o "${install_dir}/$1" "${REPO_PATH}/cmd/$1"
 }
 
 cross_build() {
+	[[ -z "${NO_CROSS}" ]] || return 0
 	local a
 	for a in amd64 arm64; do
 		echo "Building $a/$1"

build-docker

@@ -0,0 +1,57 @@
+#!/bin/bash
+
+set -e
+
+: ${DOCKER_NAME:="mantle-builder"}
+: ${GO_VERSION:="1.9.1"}
+: ${REVISION:=".0"}
+
+docker_tag="${DOCKER_NAME}:${GO_VERSION}${REVISION}"
+
+usage () {
+    echo "Usage: $(basename $0) [flags]" >&2
+    echo "Option flags:" >&2
+    echo "  -f --force    - Rebuild existing docker image." >&2
+    echo "  -h --help     - Show this help and exit." >&2
+    echo "  -p --purge    - Remove existing docker image and rebuild." >&2
+    echo "Environment:" >&2
+    echo "  DOCKER_NAME   - Default: '${DOCKER_NAME}'" >&2
+    echo "  GO_VERSION    - Default: '${GO_VERSION}'" >&2
+    echo "  REVISION      - Default: '${REVISION}'" >&2
+    echo "Docker tag: ${docker_tag}" >&2
+}
+
+while [[ $# -gt 0 ]]; do
+	case "${1}" in
+	-h | --help | help)
+		usage
+		exit 0
+		;;
+	-f | --force | force)
+		force=1
+		;;
+	-p | --purge | purge)
+		purge=1
+		;;
+	*)
+		usage
+		exit 1
+		;;
+	esac
+	shift
+done
+
+if [[ -n "${purge}" ]] && docker inspect --type image ${docker_tag} > /dev/null; then
+	echo "removing docker image: ${docker_tag}" >&2
+	docker rmi ${docker_tag}
+elif [[ -z "${force}" ]] && docker inspect --type image ${docker_tag} > /dev/null; then
+	echo "docker image exists: ${docker_tag}" >&2
+	exit 0
+fi
+
+echo "building image: ${docker_tag}" >&2
+
+docker build \
+	--build-arg GO_VERSION=${GO_VERSION} \
+	--tag ${docker_tag}\
+	.