add ca-certificates for openid

Dockerfile

@@ -7,6 +7,7 @@ RUN CGO_ENABLED=0 GOOS=linux go build -o gohttpserver .
 FROM debian:stretch
 WORKDIR /app
 RUN mkdir -p /app/public
+RUN apt-get update && apt-get install -y ca-certificates
 VOLUME /app/public
 ADD assets ./assets
 COPY --from=0 /go/src/github.com/codeskyblue/gohttpserver/gohttpserver .

README.md

@@ -64,7 +64,7 @@ go build && ./gohttpserver
 ## Docker Usage
 share current directory
 ```bash
-docker run -it -p 8000:8000 -v $PWD:/app/public --name gohttpserver codeskyblue/gohttpserver
+docker run -it --rm -p 8000:8000 -v $PWD:/app/public --name gohttpserver codeskyblue/gohttpserver
 ```
 share current directory with http oauth
 ```bash