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I've found this which walks you through creating a base bare-metal centos image. I want to however install some additional yum packages, download Python 2.7.8 and build it.

I had this in a dockerfile and already working like:

# Set the base image to Ubuntu
FROM centos:7

# File Author / Maintainer
MAINTAINER Sam Mohamed

# Update the sources list
RUN yum -y update
RUN yum install -y zlib-dev openssl-devel sqlite-devel bzip2-devel xz-libs gcc g++ build-essential make

# Install Python 2.7.8
RUN curl -o /root/Python-2.7.9.tar.xz  https://www.python.org/ftp/python/2.7.9/Python-2.7.9.tar.xz
RUN tar -xf /root/Python-2.7.9.tar.xz -C /root
RUN cd /root/Python-2.7.9 && ./configure --prefix=/usr/local && make && make altinstall

# Copy the application folder inside the container
ADD `pwd` /opt/iws_project

# Download Setuptools and install pip and virtualenv
RUN wget https://bootstrap.pypa.io/ez_setup.py -O - | /usr/local/bin/python2.7
RUN /usr/local/bin/easy_install-2.7 pip
RUN /usr/local/bin/pip2.7 install virtualenv

# Create virtualenv and install requirements:
RUN /usr/local/bin/virtualenv /opt/iws_project/venv && source /opt/iws_project/bin/activate && pip install -r /opt/iws_project/requirements.txt

How can I convert the above into a base image?

Sam Hammamy
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1 Answers1

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You are probably better off building the given Dockerfile and using the resulting image as the base for future images. This is much easier to maintain and doesn't really cost anything in terms of resource use.

But if you really want to create a single-layer "base image", the steps are as follows:

  1. Install everything you want into some directory (docker-centos-65/ in the linked tutorial).

    • You can modify the febootstrap command from the tutorial you linked to install additional yum packages by specifying more -i flags.
    • You can perform any other custom installs (e.g. Python) manually, just make sure everything ends up in the same root directory

  2. Create a tar archive of the directory where everything is installed, and pipe this to the docker import command:

    tar c -C docker-centos-65/ . | docker import - my-base-image
augurar
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  • How can I use the resulting image as the base? Every time I run docker build . it re-downloads python, and re runs all the other steps. – Sam Hammamy Aug 16 '15 at 19:23
  • Say you build the above Dockerfile as `my-base-image`. Then if you want make a derived image, you can create a new Dockerfile with the line `FROM my-base-image`. – augurar Aug 16 '15 at 19:27