Update Dockerfile & README.md

Dockerfile

@@ -1,10 +1,18 @@
-FROM golang as builder
+FROM golang:1.12 as builder
 
-RUN go get github.com/kaishuu0123/erd-go
+WORKDIR /app
+
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+
+RUN CGO_ENABLED=0 GOOS=linux go build
 
 FROM alpine
 
+RUN apk --no-cache add ca-certificates
+
 WORKDIR /erd
-COPY --from=builder /go/bin/erd-go .
+COPY --from=builder /app/erd-go .
 
 ENTRYPOINT ["/erd/erd-go"]

README.md

@@ -1,7 +1,12 @@
 # erd-go
 
+[![GitHub release](https://img.shields.io/github/release/kaishuu0123/erd-go.svg)][releases]
 [![Build Status](https://travis-ci.org/kaishuu0123/erd-go.svg?branch=master)](https://travis-ci.org/kaishuu0123/erd-go)
 [![Coverage Status](https://coveralls.io/repos/github/kaishuu0123/erd-go/badge.svg)](https://coveralls.io/github/kaishuu0123/erd-go)
+[![Docker Pulls](https://img.shields.io/docker/pulls/kaishuu0123/erd-go.svg)][docker]
+
+[releases]: https://github.com/kaishuu0123/erd-go/releases
+[docker]: https://hub.docker.com/r/kaishuu0123/erd-go/
 
 Translates a plain text description of a relational database schema to a graphical entity-relationship diagram.(convert to dot file)
 
@@ -11,7 +16,7 @@ Translates a plain text description of a relational database schema to a graphic
 
 get binary from [releases page](https://github.com/kaishuu0123/erd-go/releases).
 
-or 
+or
 
 ```
 go get github.com/kaishuu0123/erd-go
@@ -50,6 +55,12 @@ ex.) convert to png from dot (use dot command)
 cat examples/nfldb.er | erd-go | dot -Tpng -o nfldb.png
 ```
 
+## Usage (Used by Docker container)
+
+```
+cat examples/nfldb.er | docker run --rm -i kaishuu0123/erd-go | docker run --rm -i risaacson/graphviz dot -T png > nfldb.png
+```
+
 ## Example
 
 see [examples directory](https://github.com/kaishuu0123/erd-go/blob/master/examples)