Add Centos 6.5 build instructions

README.md

@@ -51,11 +51,13 @@ Omnibus-gitlab uses four different directories.
 - `/var/log/gitlab` contains all log data generated by components of
   omnibus-gitlab.
-## Preparing a build environment on Ubuntu 12.04
-To create builds you will need a build user (`ubuntu:ubuntu` in our example).
+## Preparing a build environment
+To create builds you will need a build user (`omnibus-build:omnibus-build` in our example).
 Preparing the build machine requires sudo access.
+### Ubuntu 12.04
+
 ```shell
 # Install dependencies
 sudo apt-get install ruby1.9.1 ruby1.9.1-dev git build-essential
@@ -63,11 +65,11 @@ sudo gem install --no-ri --no-rdoc bundler
 # Create build directories for use by the build user
 sudo mkdir -p /opt/gitlab /var/cache/omnibus
-# We assume the build user and group is 'ubuntu'
-sudo chown ubuntu:ubuntu /opt/gitlab /var/cache/omnibus
+# We assume the build user and group is 'omnibus-build'
+sudo chown omnibus-build:omnibus-build /opt/gitlab /var/cache/omnibus
 ```
-Then, as the build user:
+Then, as the build user (omnibus-build):
 ```shell
 # Clone the omnibus repo
@@ -76,6 +78,43 @@ git clone https://gitlab.com/gitlab-org/omnibus-gitlab.git
 # Install gem dependencies for omnibus-ruby
 cd omnibus-gitlab
 bundle install --path .bundle --binstubs
+
+# Do a build (and take a break from the computer)
+bin/omnibus build project gitlab
+```
+
+### Centos 6.5
+
+```shell
+sudo yum groupinstall 'Development Tools'
+# Install RedHat Software Collections to get Ruby 1.9.3
+sudo yum install centos-release-SCL
+sudo yum install ruby193 ruby193-ruby-devel
+
+# Create build directories for use by the build user
+sudo mkdir -p /opt/gitlab /var/cache/omnibus
+# We assume the build user and group is 'omnibus-build'
+sudo chown omnibus-build:omnibus-build /opt/gitlab /var/cache/omnibus
+```
+
+As the build user (omnibus-build):
+
+```shell
+# Enable Ruby 1.9.3 from Software Collections
+echo 'exec scl enable ruby193 bash' >> .bash_profile
+# Start a new login shell so we do not have to log out and in
+# this one time
+bash --login
+
+# Clone the omnibus repo
+git clone https://gitlab.com/gitlab-org/omnibus-gitlab.git
+
+# Install gem dependencies for omnibus-ruby
+cd omnibus-gitlab
+bundle install --path .bundle --binstubs
+
+# Do a build (and take a break from the computer)
+bin/omnibus build project gitlab
 ```
 ## Usage