Using Docker to Generate Pretty man pages

Let's say we want to compare man pages for a particular package across different distributions. We can use Docker as a quick and easy way to pull down man pages for any Linux distro. We can take it one step further to set up a Docker image whose job it is to generate HTML man pages for a particular distro.

Make your own image with the docs

yum install -y dosfstools pykickstart squashfs-tools system-config-keyboard rpm -ivh http://people.centos.org/arrfab/CentOS7/LiveMedia/RPMS/python-imgcreate-20.1-2.el7.x86_64.rpm git clone git@github.com:katzj/ami-creator.git yum install python-pip pip install ez_setup cd ami-creator python setup.py install

cd git clone git@github.com:sprin/sig-cloud-instance-build.git cd sig-cloud-instance-build/docker ami-creator -c centos-7.ks

# Assuming docker is running ./img2docker.sh centos-7-201409302151.img manpages

Manually Configuring an Image

Run a Centos 7 container, downloading first if not already locally available:

docker run -it --name man2html_ctr sprin/centos7:manpages /bin/bash

Inside the container, install man2html:

yum install -y man2html

Quit the container with Ctrl-D. Let's see the image we just pulled:

docker images

Now let's list all containers, including the one that we just exited:

docker ps -a

We can commit the changes we made to the container to a new image. The first arg is the container name, and the second is the image name.

docker commit man2html_ctr man2html_img

Let's see it in the list:

docker images

Now let's generate some nice manpages with that new image!

docker run man2html /bin/bash -c '/usr/bin/gunzip -c $(man -w systemd) | /usr/bin/man2html' > /tmp/tmp.html && open /tmp/tmp.html

Good old Readability

http://www.tobez.org/download/readability.html

Dockerfiles

git clone git@github.com:sprin/docker-man2html.git
cd docker-man2html
docker build -t man2html .

Now we have an image identical to the first one, but created automatically using the definition in the Dockerfile.

Daemons in my Dockers

Let's run an nginx daemon:

docker run -d -p 80 --name nginx nginx

This will expose port 80 of the nginx container on a random port, which you can see with docker ps.

Extra Credit!

Try linking the man2html container to the nginx container so nginx can serve the generated HTML files.