I want to use a CNAME as a level of indirection
( to point N webservers at the active mySQL replica).
I''d like to use /etc/hosts to avoid the DNS propagation delays.
I don''t want to do away with DNS altogether though - is it possible to
lookup
a hostname and pass that IP to the hosts type? Something like:
# this gets used by several classes
$activedbhost = "mysql1.mydomain.com"
host { "db.hosting.mydomain.com":
ensure => present,
ip => ip_of($activedbhost)
}
''ip_of()'' is what Puppet calls a ''function'',
right?
Does anyone have a reference on how to write them -
the reductive labs docs seem a little broken today.
Or better still, has someone already written such a thing :)
--
You received this message because you are subscribed to the Google Groups
"Puppet Users" group.
To post to this group, send email to puppet-users@googlegroups.com.
To unsubscribe from this group, send email to
puppet-users+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/puppet-users?hl=en.
On Wed, Feb 24, 2010 at 6:55 AM, Dick Davies <rasputnik@hellooperator.net> wrote:> Does anyone have a reference on how to write functions - > the reductive labs docs seem a little broken today.Never mind, found it. http://reductivelabs.com/trac/puppet/wiki/WritingYourOwnFunctions -- You received this message because you are subscribed to the Google Groups "Puppet Users" group. To post to this group, send email to puppet-users@googlegroups.com. To unsubscribe from this group, send email to puppet-users+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/puppet-users?hl=en.
Dick Davies wrote:> # this gets used by several classes > $activedbhost = "mysql1.mydomain.com" > > host { "db.hosting.mydomain.com": > ensure => present, > ip => ip_of($activedbhost) > } > > ''ip_of()'' is what Puppet calls a ''function'', right? > Does anyone have a reference on how to write them - > the reductive labs docs seem a little broken today. > > Or better still, has someone already written such a thing :)As a matter of fact, yes, I have. :-) In my "nsc-puppet-utils" module, I have a function resolve_ipnets() which does that. (It does have some additional features as well. For example, it resolves names on the form "foo.example.com/24" to "10.20.30.17/24", and it handles lists of hostnames as well.) Do a ''git clone http://www.nsc.liu.se/~bellman/nsc-puppet-utils.git'' to get my module. There is documentation inside the file plugins/puppet/parser/functions/resolve_ipnets.rb. A little note, though. If you use this to populate /etc/hosts from DNS, and you do so on your Puppetmaster, you won''t be able to change the address of that name. The next time resolve_ipnets() is called, it will find the address in /etc/hosts, and then you''re stuck. (You can of course remove that entry from /etc/hosts manually, and then you''ll be OK again, but that''s cheating. :-) /Bellman -- You received this message because you are subscribed to the Google Groups "Puppet Users" group. To post to this group, send email to puppet-users@googlegroups.com. To unsubscribe from this group, send email to puppet-users+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/puppet-users?hl=en.
On Wed, Feb 24, 2010 at 2:07 PM, Thomas Bellman <bellman@nsc.liu.se> wrote:> Dick Davies wrote:>> host { "db.hosting.mydomain.com": >> ensure => present, >> ip => ip_of($activedbhost) >> } >> >> ''ip_of()'' is what Puppet calls a ''function'', right? >> Does anyone have a reference on how to write them - >> the reductive labs docs seem a little broken today. >> >> Or better still, has someone already written such a thing :) > > As a matter of fact, yes, I have. :-) > > In my "nsc-puppet-utils" module, I have a function resolve_ipnets() > which does that. (It does have some additional features as well. > For example, it resolves names on the form "foo.example.com/24" > to "10.20.30.17/24", and it handles lists of hostnames as well.) > > Do a ''git clone http://www.nsc.liu.se/~bellman/nsc-puppet-utils.git'' > to get my module.Nice, thanks - lot of useful stuff there. I went for a dirt simple: [rasputnik@puppet lamp]# cat plugins/puppet/parser/functions/ip_of.rb module Puppet::Parser::Functions require ''resolv'' newfunction(:ip_of, :type => :rvalue) do |args| hostname = args[0] Resolv.getaddress(hostname) end end So I can now do: class webserver { ... host { "$lamp::cfg::mysql_alias": ensure => present, ip => ip_of("$lamp::cfg::mysql_master") } ... } and the webservers all get an /etc/hosts entry for whichever mysql backend is set to be active in my settings class (to avoid having to edit 150+ wp-config.phps). A 2:5 useful code to boilerplate ratio is pretty good for a plugin framework, so I think I''ll stick with mine for now (and maybe pinch yours if we need to generalize things :) ) Thanks again for the other functions, though. I''ll use them as a reference when we start getting more heavily into custom functions. -- You received this message because you are subscribed to the Google Groups "Puppet Users" group. To post to this group, send email to puppet-users@googlegroups.com. To unsubscribe from this group, send email to puppet-users+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/puppet-users?hl=en.