Minor build improvements

Makefile

* Make Go build flags parameterizable
  * Verbose by default
  * Do not force complete rebuild
  * Remove unnecessary '-installsuffix' flag
    https://plus.google.com/117192131596509381660/posts/eNnNePihYnK
* Log build steps
* Rename 'clean' target to 'clean-container'
* Move artifact copy to '.container' target
* Add 'clean' target

Shell script

* Fix shellcheck SC2068
  https://github.com/koalaman/shellcheck/wiki/SC2068
* Reject mandatory vars with empty values

build/build.sh

@@ -28,20 +28,21 @@ mandatory=(
 )
 
 missing=false
-for var in ${mandatory[@]}; do
-  if [[ -z "${!var+x}" ]]; then
+for var in "${mandatory[@]}"; do
+  if [[ -z "${!var:-}" ]]; then
     echo "Environment variable $var must be set"
     missing=true
   fi
 done
 
-if [ "$missing" = true ];then
+if [ "$missing" = true ]; then
   exit 1
 fi
 
 export CGO_ENABLED=0
 
-go build -a -installsuffix cgo 	\
+go build \
+    ${GOBUILD_FLAGS} \
     -ldflags "-s -w \
         -X ${PKG}/version.RELEASE=${TAG} \
         -X ${PKG}/version.COMMIT=${GIT_COMMIT} \

build/go-in-docker.sh

@@ -56,6 +56,7 @@ TAG=${TAG:-"0.0"}
 HOME=${HOME:-/root}
 KUBECONFIG=${HOME}/.kube/config
 GOARCH=${GOARCH}
+GOBUILD_FLAGS=${GOBUILD_FLAGS:-"-v"}
 PWD=${PWD}
 BUSTED_ARGS=${BUSTED_ARGS:-""}
 REPO_INFO=${REPO_INFO:-local}