[chef] Re: defining a global variable to avoid sprinkles

[AJ Christensen < >]

Yo,

Couple of anti-patterns emerging in this post, quick attempt to enlighten:

On 10 January 2012 09:40,  
<
 >
 wrote:
>
> i'm finding myself sprinkling my cookbooks with repeated code, and wondering
> how i can do this differently. i'm in ec2. let's say i want to define
> subdomains keyed off of 2 things: a userdata setting and
> placement_availability_zone:
>
> if userdata contains "-e dev" and av zone matches us-east-1, subdomain is 
> dev.abfabreunion.com.
> if userdata contains "-e prod" and av zone matches us-east-1, subdomain is 
> prod.abfabreunion.com.
> and so on.
>
> i'd want to make that derived subdomain available to all of my cookbooks. is
> there a way to do that in chef without sprinkling my code with the 
> following?
>
>

In general the logical identifier of a node as a hostname is often set
up by sysadmins.

Are the hostnames you mention below registered automatically via API
or similar, or manually managed?

> mrepo/attributes/default.rb:
>
> if node[:ec2][:userdata] =~ /-e dev/ && 
> node[:ec2][:placement_availability_zone] =~ /us-east-1/
>  node.default[:mrepo][:smtpserver] = "mail1.dev.abfabreunion.com"
> elsif node[:ec2][:userdata] =~ /-e prod/ && 
> node[:ec2][:placement_availability_zone] =~ /us-east-1/
>  node.default[:mrepo][:smtpserver] = "mail1.prod.abfabreunion.com"
> elsif node[:ec2][:userdata] =~ /-e prod/ && 
> node[:ec2][:placement_availability_zone] =~ /us-west-2/
>  node.default[:mrepo][:smtpserver] = "mail1.prod2.abfabreunion.com"
> end

In this particular case, the obvious solution to me is to use Chef
Search to locate the smtp server for the environment. Consider
something like

# just a node, so you can access the usual stuff
mrepo_smtpserver = search(:node, "role:whatever_smtp_role AND
ec2_placement_availability_zone:us-east-1 AND
chef_enviornment:#{node.chef_environment}")
mrepo_smtpserver[:ec2][:public_hostname]

You could easily store these attributes in a databag, instead of on
the node itself, too.. e.g.:

mrepo_smtpserver = data_bag_item "mrepo_smtpserver", node.chef_environment

Anyway I'm circling back to my original point: you should avoid hard
coding "target" attributes on client systems and instead make use of
one of many methods for dynamically registering or locating parts of
your infrastructure.

Hope this helps?

Cheers,

--AJ

>
>
> openvpn/attributes/default.rb:
>
> if node[:ec2][:userdata] =~ /-e dev/ && 
> node[:ec2][:placement_availability_zone] =~ /us-east-1/
>  node.default[:openvpn][:dhcpdomain] = "dev.abfabreunion.com"
> elsif node[:ec2][:userdata] =~ /-e prod/ && 
> node[:ec2][:placement_availability_zone] =~ /us-east-1/
>  node.default[:openvpn][:dhcpdomain] = "prod.abfabreunion.com"
> elsif node[:ec2][:userdata] =~ /-e prod/ && 
> node[:ec2][:placement_availability_zone] =~ /us-west-2/
>  node.default[:openvpn][:dhcpdomain] = "prod2.abfabreunion.com"
> end
>
> and so on.
>
> thanks,
> kallen
>
>