Introducing the Dockerfile

In this section, we will cover Dockerfiles in depth, along with the best practices to use. So what is a Dockerfile?

A Dockerfile is simply a plain text file that contains a set of user-defined instructions. When the Dockerfile is called by the docker image build command, which we will look at next, it is used to assemble a container image. A Dockerfile looks like the following:

FROM alpine:latest
LABEL maintainer="Russ McKendrick <[email protected]>"
LABEL description="This example Dockerfile installs NGINX."
RUN apk add --update nginx && \
    rm -rf /var/cache/apk/* && \
    mkdir -p /tmp/nginx/

COPY files/nginx.conf /etc/nginx/nginx.conf
COPY files/default.conf /etc/nginx/conf.d/default.conf
ADD files/html.tar.gz /usr/share/nginx/

EXPOSE 80/tcp

ENTRYPOINT ["nginx"]
CMD ["-g", "daemon off;&quot...