Allow to build for a specific platform (#250)

pkg/cli/scripts/build.sh

@@ -2,9 +2,16 @@
 #
 # build.sh compiles dnote binary for target platforms. It is resonsible for creating
 # distributable files that can be released by a human or a script.
-# use: ./scripts/build.sh 0.4.8
+#
+# It can either cross-compile for different platforms using xgo, simply target a specific
+# platform. Set GOOS and GOARCH environment variables to disable xgo and instead
+# compile for a specific platform.
+#
+# use:
+# ./scripts/build.sh 0.4.8
+# GOOS=linux GOARCH=amd64 ./scripts/build.sh 0.4.8
 
-set -eux
+set -ex
 
 version=$1
 projectDir="$GOPATH/src/github.com/dnote/dnote"
@@ -43,18 +50,33 @@ get_binary_name() {
 build() {
   platform=$1
   arch=$2
+  # native indicates if the compilation is to take place natively on the host platform
+  # if not true, use xgo with Docker to cross-compile
+  native=$3
 
   # build binary
   destDir="$outputDir/$platform-$arch"
+  ldflags="-X main.apiEndpoint=https://api.dnote.io -X main.versionTag=$version"
+  tags="fts5"
 
   mkdir -p "$destDir"
-  xgo \
-    -go "$goVersion" \
-    -ldflags "-X main.apiEndpoint=https://api.dnote.io -X main.versionTag=$version" \
-    --targets="$platform/$arch" \
-    --tags "fts5" \
-    --dest="$destDir" \
-    "$basedir"
+
+  if [ "$native" == true ]; then
+    GOOS="$platform" GOARCH="$arch" \
+      go build \
+        -ldflags "$ldflags" \
+        --tags "$tags" \
+        -o="$destDir/cli-$platform-$arch" \
+        "$basedir"
+  else
+    xgo \
+      -go "$goVersion" \
+      --targets="$platform/$arch" \
+      -ldflags "$ldflags" \
+      --tags "$tags" \
+      --dest="$destDir" \
+      "$basedir"
+  fi
 
   binaryName=$(get_binary_name "$platform")
   mv "$destDir/cli-${platform}-"* "$destDir/$binaryName"
@@ -74,9 +96,13 @@ build() {
   popd
 }
 
-# fetch tool
-go get -u github.com/karalabe/xgo
+if [ -z "$GOOS" ] && [ -z "$GOARCH" ]; then
+  # fetch tool
+  go get -u github.com/karalabe/xgo
 
-build linux amd64
-build darwin amd64
-build windows amd64
+  build linux amd64
+  build darwin amd64
+  build windows amd64
+else
+  build "$GOOS" "$GOARCH" true
+fi