[chef] A weird template file

[Sam Su < >]

Hi,

I am learning chef with some real cookbooks, here is the one of my learning cookbooks link: https://github.com/stackforge/cookbook-openstack-network

Usually I add a recipe (e.g. openstack-network::openvswitch) into a node's run list, then run and check the result at the client node.

I found that the file /etc/quantum/quantum.conf is a different result than expected in the template file quantum.conf.erb.

The weird part of the quantum.conf is shown as below, we can see the line started with rpc_backend (red text):

# =========== items for agent scheduler extension =============

# Driver to use for scheduling network to DHCP agent

network_scheduler_driver = quantum.scheduler.dhcp_agent_scheduler.ChanceScheduler

# Driver to use for scheduling router to a default L3 agent

router_scheduler_driver = quantum.scheduler.l3_agent_scheduler.ChanceScheduler

rpc_backend = quantum.openstack.common.rpc.impl_qpid

# Allow auto scheduling networks to DHCP agent. It will schedule non-hosted

...

However at the original template file quantum.conf.erb (shown at the following) I cannot find the line at the same location:

# =========== items for agent scheduler extension =============

# Driver to use for scheduling network to DHCP agent

network_scheduler_driver = <%= node["openstack"]["network"]["dhcp"]["scheduler"] %>

# Driver to use for scheduling router to a default L3 agent

router_scheduler_driver = <%= node["openstack"]["network"]["l3"]["scheduler"] %>

# Allow auto scheduling networks to DHCP agent. It will schedule non-hosted

...

I tried to search the whole cookbook with the key words "rpc_backend" or "quantum.conf.erb" but no help.

I am wondering where the line ("rpc_backend  ...") comes from in the file quantum.conf. 

It has puzzled me for several days, if someone can help me out, it will be much appreciated.

Thanks,

Sam