update Dockerfile

Author: wzshiming

Dockerfile

@@ -1,8 +1,10 @@
 FROM golang:1.10-alpine3.7 AS builder
 WORKDIR /go/src/github.com/wzshiming/pic2ascii/
 COPY . .
-RUN CGO_ENABLED=0 go install -a -ldflags '-s' ./cmd/...
+RUN apk add -U gcc libc-dev ffmpeg-dev ffmpeg-libs
+RUN go install -tags support_video -a -ldflags '-s -w'  ./cmd/...
 
-FROM scratch
-COPY --from=builder /go/bin/pic2ascii /
-ENTRYPOINT [ "/pic2ascii" ]
+FROM alpine:3.7
+COPY --from=builder /go/bin/pic2ascii /usr/local/bin/
+RUN apk add -U --no-cache ffmpeg-libs
+ENTRYPOINT [ "pic2ascii" ]