08 Jun 2015

Building chef from source to change Prefix

There may be times when you want chef to be located somewhere besides /opt/chef. Currently you can’t just use rpm --prefix=/data/myapp to move it to a different location due to compile time settings, so lets compile chef using omnibus to store it under /data/myapp/chef.

First we need three repos that comprise omnibus for chef -

$ git clone git@github.com:chef/opscode-omnibus.git
$ git clone git@github.com:chef/omnibus-software.git
$ git clone git@github.com:chef/omnibus-chef.git

Then lets checkout the version of omnibus-chef that is closest without going over the version of chef we’d like to install. omnibus-chef and chef versions do not match 1-1.

$ cd omnibus-chef
# git tag list # to list tags
# git checkout tags/<version here>
$ git checkout tags/chef-12.2.0

I’m building RPMs for centos. omnibus will build the package for whatever platform it is run on.

Lets Edit a few files for our usecase -

.kitchen.yml

# Change the box to something that can be downloaded from vagrant cloud
# in this case I replaced centos-6.5 with chef/centos-6.5
  - name: chef/centos-6.5
....
# Change the install_dir to the location you want the RPM to be installed
attributes:
  omnibus:
    <<: *attribute_defaults
        install_dir: /data/myapp/chef

We need to override the default_root in the omnibus-chef project to set the new root. Its originally set in the omnibus package, but we’ll just hax it here quick:

config/projects/chef.rb

default_root = "/data/myapp"

Lastly pin the version of chef you’d like installed

config/projects/chef.rb [0]

override :chef, version: "12.3.0"
override :ohai, version: "8.3.0"

Optionally edit, or remove, the package-scripts/chef/postinst script. In my case I wanted it to not touch other parts of the file system so I commented it out. Most cases you’d just change this line -

INSTALLER_DIR=/data/myapp/chef

$ kitchen converge chef-chef-centos-65
$ kitchen login chef-chef-centos-65
# Setup Env (dont worry about the error)
$ source ./load-omnibus-toolchain.sh
$ cd omnibus-chef
$ bundle install --without development

$ bundle exec omnibus build chef

# Clean out dir if you have an issue or change versions you're building
$ bundle exec omnibus clean chef

You then should have a package under the pkg/ folder ready to test out!

[0] - Example pin of chef version - https://github.com/chef/omnibus-chef/commit/0afd9bbe9df486ccebf5908b4f17a1b013860abc

Want to contribute to this article? Edit this post on Github!