While I'm working on the oo- script for parsing the cartridge manifest, I discovered that the haproxy grep/sed/tr magic could be replaced by a bash function in the OpenShift Bash SDK:

function primary_cart_manifest {
  ruby -ryaml -e "p YAML.load_file('$OPENSHIFT_PRIMARY_CARTRIDGE_DIR/metadata/manifest.yml')$1"
}

Then you can call this function using:

first_ip_in_manifest=$(primary_cart_manifest "['Endpoints'].first['Private-IP-Name']")

If you look at v2_cart_model.rb 'primary_cartridge' method, this function is not very different
as what the method is doing.

The difficulty I have with creating the oo- script for manifest parsing is the YAML format
of the manifest... You need to deal with things like Array's and Hash'es, so the syntax
could be pretty wild:

$ oo-cartridge-manifest -c 52398bc711fae092a1000007 primary -n 'Private-IP-Name' --endpoint 1

The same applies for other properties in manifest.yaml (--compatible-versions, etc..) Basically
the oo- script will need to map the YAML keys into 'options', which might turn into maintenance
nightmare ;-)

What do you guys think?

Commit pushed to master at https://github.com/openshift/origin-server

https://github.com/openshift/origin-server/commit/086363bdce6736849064e3a683ca1294a9fdec34
Bug 1007455 - Added primary_cartridge methods to Ruby SDK

It's fixed, verified on devenv_3821, please refer to the following results:

1. Create a scaled app
rhc app create cpl0s0 perl-5.1 -s --no-git
2. SSH into this app
rhc ssh cpl0s0
3. Check scripts code
grep -e first_ip_in_manifest -e first_port_in_manifest haproxy/hooks/set-proxy
4. Check the primary endpoint variables
env |grep  PERL

at step 3: 
    first_ip_in_manifest=$(primary_cartridge_private_ip_name)
    prim_cart_ip="OPENSHIFT_${prim_cart}_${first_ip_in_manifest}"
    first_port_in_manifest=$(primary_cartridge_private_port_name)
    prim_cart_port="OPENSHIFT_${prim_cart}_${first_port_in_manifest}"

at step 4:
OPENSHIFT_PERL_VERSION=5.10
PERL5LIB=/var/lib/openshift/52424f7e617cec7634000007/app-root/runtime/repo/libs:/var/lib/openshift/52424f7e617cec7634000007/perl/perl5lib/lib/perl5/
OPENSHIFT_PERL_IDENT=redhat:perl:5.10:0.0.5
OPENSHIFT_PERL_PROXY_PORT=38031
OPENSHIFT_PERL_PORT=8080
OPENSHIFT_PERL_DIR=/var/lib/openshift/52424f7e617cec7634000007/perl/
OPENSHIFT_PERL_IP=127.1.244.1
OPENSHIFT_PERL_LOG_DIR=/var/lib/openshift/52424f7e617cec7634000007/perl//logs/