docker: Enable multi stage container build for docker containers.

Fixes #1

Dockerfile

@@ -1,13 +1,27 @@
+FROM golang:latest
+
+RUN mkdir -p /go/src/github.com/Ch3ck/youtube-dl/
+
+WORKDIR /go/src/github.com/Ch3ck/youtube-dl
+
+COPY vendor     vendor
+COPY ytd.go  .
+
+RUN gofmt -l -d $(find . -type f -name '*.go' -not -path "./vendor/*") \
+  && CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o ytd .
+
+
 FROM alpine:latest
+
 MAINTAINER Nyah Check <check.nyah@gmail.com>
 
 ENV PATH /go/bin:/usr/local/go/bin:$PATH
 ENV GOPATH /go
 
-RUN	apk add --no-cache \
-	ca-certificates
+RUN	apk add --no-cache add ca-certificates
 
-COPY . /go/src/github.com/Ch3ck/ytd
+WORKDIR /root/
+COPY --from=0 /go/src/github.com/Ch3ck/ytd .
 
 RUN set -x \
 	&& apk add --no-cache --virtual .build-deps \
@@ -16,11 +30,12 @@ RUN set -x \
 		gcc \
 		libc-dev \
 		libgcc \
+		ffmpeg \
 	&& cd /go/src/github.com/Ch3ck/ytd \
 	&& go build -o /usr/bin/ytd . \
 	&& apk del .build-deps \
 	&& rm -rf /go \
 	&& echo "Build complete."
 
 
-ENTRYPOINT [ "ytd" ]
+CMD [ "./ytd" ]

Makefile

@@ -12,7 +12,7 @@ all: clean fmt vet build test install
 build: fmt vet
 	@echo "+ $@"
 	@go build -tags "$(BUILDTAGS) cgo" . ## Thinking of downloading the required go deps in here.
-	#@docker build -t ch3ck/ytd:v1 . Disable docker build.
+	@docker build -t ch3ck/ytd:v1 . 
 
 static:
 	@echo "+ $@"