refactor build code, updated hugo version.

docker/scripts/build_hugo.sh

@@ -0,0 +1,22 @@
+#! /bin/sh
+
+set -e
+
+hugo_version=${HUGO_VERSION:-0.87.0}
+
+echo "downloading build dependencies..."
+apk add -U --no-cache git build-base
+
+LDFLAGS="-s -w -X github.com/gohugoio/hugo/common/hugo.buildDate=\$(date +%Y-%m-%dT%H:%M:%SZ) -X github.com/gohugoio/hugo/common/hugo.commitHash=\$(git rev-parse --short HEAD)"
+
+echo "downloading hugo version v$hugo_version..."
+git clone --branch "v$hugo_version" https://github.com/gohugoio/hugo.git
+
+echo "building hugo..."
+cd hugo
+
+CGO_ENABLED=0 go build -ldflags "\"$LDFLAGS\"" -o /tmp/hugo .
+
+CGO_ENABLED=1 go build -tags extended -ldflags "\"$LDFLAGS\"" -o /tmp/hugo-extended
+
+echo "done."