How to install multiple packages using apt-get via a Dockerfile

Question

So I am trying to make a basic Dockerfile, but when I run this it says

The command bin/sh -c sudo apt-get install git python-yaml python-jinja2 returned a non-zero code: 1

My question is what am I doing wrong here, and is it even allowed to do commands like 'cd' and 'source' from the Dockerfile?

FROM Ubuntu
MAINTAINER example

#install and source ansible
RUN sudo apt-get update
RUN sudo apt-get install git python-yaml python-jinja2 python-pycurl
RUN sudo git clone https://github.com/ansible/ansible.git
RUN sudo cd ansible
RUN sudo source ./hacking/env-setup

Answer 1

Couple of pointers / comments here:

• It's ubuntu not Ubuntu
• From base ubuntu (and unfortunately, a lot of images) you don't need to use sudo, the default user is root (and in ubuntu, sudo is not included anyway)
• You want your apt-get update and apt-get install to be RUN as part of the same command, to prevent issues with Docker's layer cache
• You need to use the -y flag to apt-get install as the Docker build process runs non-interactively
• Few other points I could make about clearing up your apt-cache and other non-required artifacts after running the commands, but this should be enough to get going on

New Dockerfile (taking into account the above) would look something like:

FROM ubuntu
MAINTAINER example

#install and source ansible
RUN apt-get update && apt-get install -y \
    git \
    python-yaml \
    python-jinja2 \
    python-pycurl

RUN git clone https://github.com/ansible/ansible.git
WORKDIR ansible/hacking
RUN chmod +x env-setup; sync \
    && ./env-setup

You might also find it useful to read the Dockerfile best practises.

Edit: Larsks answer also makes some useful points about the state of the container not persisting between layers so you should go upvote him too!