docker volume practice

docker run -d -P --name web -v /webapp training/webapp python app.py
docker run -d -P --name web -v /opt/webapp:ro training/webapp python app.py
docker inspect web
docker run -d -P --name web -v /src/webapp:/opt/webapp training/webapp python app.py

docker rm nostalgic_morse
docker run -t -i ubuntu:14.04 /bin/bash

docker images
docker pull centos
docker pull training/sinatra

docker run -t -i training/sinatra /bin/bash

Dockerfile
use a Dockerfile to specify instructions to create an image.
docker commit -m "Added json gem" -a "Kate Smith" \ 0b2616b0e5a8 ouruser/sinatra:v2

$ mkdir sinatra 
$ cd sinatra 
$ touch Dockerfile
docker build

Dockerfile
FROM ubuntu:14.04 
MAINTAINER Kate Smith  
RUN apt-get update && apt-get install -y ruby ruby-dev 
RUN gem install sinatra

docker tag 5db5f8471261 ouruser/sinatra:devel
docker push ouruser/sinatra
docker rmi training/sinatra

docker run -d --name db training/postgres
docker rm -f web
docker run -d -P --name web --link db:db training/webapp python app.py
https://docs.docker.com/userguide/dockervolumes/