On Wed, 12 Jun 2013, Ivan Voras wrote: > Hello, > > I'm not sure this is the place to ask my question, and it any case
Most definitely the right place to ask. > this is something which looks so trivial that I must be missing > something, but - how to parametrize the cloud-config YAML files with > variable expansion? > > Specifically, I need it for a scenario where I'm installing chef with > cloud-init, and one of the attributes chef has is "node_name" which if > not set defaults to the instance id, a string of the form > "i-0000009f". This non-human-readable string then gets registered as > the node name in Chef, but instead of that, I'd like to use the > hostname as created and passed by the cloud infrastructure (OpenStack > in my case). > > I'm sure this is not the only place where it would be nice to > customize the cloud-config data with some actual dynamic information > so - how can it be done? I've tested some of the "usual suspects" in a > string like "test %(hostname) %(fqdn) %(instance_id) $fqdn %f > $INSTANCE_ID" but none of those work. > > Any ideas? cloud-config data is not 'rendered' itself in any way. Ie, it doesn't do variable substitution in the cloud-config content before processing. Some config-modules consider input to them to be cheetah template content. One example is the apt_configure that allows apt-source lines that are added to contain: $RELEASE or $MIRROR. 'update_etc_hosts' is another one. It uses a template in /etc/cloud/templates that can have variables in it. There is a request for access to more variables (similar to what you're asking for) in bug 1020695 (http://pad.lv/1020695). Both your request and the one above do seem reasonable, and it might make sense to extend the chef config module with access to more variables. In a "less integrated" manner, I'd also like to see the return of "cloud-init-query". If you've used ec2, you might be familiar with the 'ec2-metadata' command: $ ec2metadata --instance-id i-00003c0a The goal of cloud-init-query would be to provide access to similar information, but in a data-source agnostic way. Ie 'cloud-init-query --instance-id' would "just work" on ec2 and on openstack with config-drive or even the local data source. It may make good sense to basically provide access to all the same variables or data that 'cloud-init-query' would have. So, unfortunately I don't have a simple answer to get you unstuck, but I am interested in thinking about this, and interested in feedback, thoughts, solutions, patches ... Scott -- Mailing list: https://launchpad.net/~cloud-init Post to : [email protected] Unsubscribe : https://launchpad.net/~cloud-init More help : https://help.launchpad.net/ListHelp
