[chef] Re: Re: render partial template only if the node['fqdn']-partial exists

OK.. I found a solution:

The main template, my.cnf.erb:
 [mysqld]
 server-id = <%= @server_id %>
 report-host = <%= node['fqdn'] %>
 !include /etc/mysql/_my.cnf_<%= node['ec2']['instance_type'] %>
 !include /etc/mysql/_my.cnf.global_<%= @mysql_version %>
 !include /etc/mysql/_my.cnf.instance_specific_overrides     <-- the new line


In the templates dir in the cookbook:
  $ cat templates/default/my.cnf.instance_specific_overrides.erb
  # A placeholder for overrides for specific fqdn

  $ cat 
templates/host-db26.dev.example.com/my.cnf.instance_specific_overrides.erb
  # Overrides specific to <%= node['fqdn'] %>
  [mysqld]
  expire_logs_days=5
  replicate-wild-ignore-table = foo_bar.KBToyAndHobby%


Two template resources in the recipe:

  template "/etc/mysql/my.cnf" do
    source "my.cnf.erb"
    owner "root"
    group "root"
    mode 00644
    variables :server_id     => node['tokopf-bar']['mysql']['server_id'],
              :mysql_version => node['tokopf-bar']['mysql']['mysql_version']
  end

  template 
"#{node['tokopf-bar']['mysql']['conf_dir']}/_my.cnf.instance_specific_overrides"
 do
    source "my.cnf.instance_specific_overrides.erb"
    owner "root"
    group node['tokopf-bar']['mysql']['root_group']
    mode 00644
  end


On a given node during a chef-client run, if this dir exists with this file in
it, chef will lay down this file:

  templates/host-FQDN/my.cnf.instance_specific_overrides.erb

Otherwise, chef will lay down the override file found in the default dir.

Either way, the resulting my.cnf is happy.

yay
kallen


On Mon, 12 May 2014, Noah Kantrowitz wrote:

> I don't think this is currently possible without a lot of extra work. The 
> complex way would be to look at the cookbook metadata in the cookbook 
> collection to see what template files exist. This is definitely not how 
> templates are intended to be used at present though.
>
> --Noah
>
> On May 12, 2014, at 12:13 PM, 
> 
 
>  wrote:
>
> >
> > Hiya,
> >
> > How can I render a base template *plus* a partial template only if the 
> > partial
> > exists for node['fqdn']? Is there a way to do this? The way I see it now, 
> > the
> > only way I can do this is to create a per-fqdn erb files in my cookbook 
> > for
> > every host, even if only a few of them actually need to render the 
> > partial. I'll
> > bet there's a better way to do this, I just don't see it yet.
> >
> > Let's say I have a bunch of mysql database hosts, and most of them can 
> > render
> > their my.cnf following one standard. And let's say sometimes I have a 
> > need to
> > extend the standard by appending extra config lines for only some of the 
> > db
> > hosts.
> >
> > Here are examples of the rendered my.cnf I want, the first is for a db 
> > host that
> > has no special config lines, the second for a db host that needs a lil 
> > extra:
> >
> >  [mysqld]
> >  server-id = 14050101
> >  report-host = db14b.dev.example.com
> >  !include /etc/mysql/_my.cnf_m3.large
> >  !include /etc/mysql/_my.cnf.global_5.5
> >
> >
> >  [mysqld]
> >  server-id = 14050701
> >  report-host = db26b.dev.example.com
> >  !include /etc/mysql/_my.cnf_m3.large
> >  !include /etc/mysql/_my.cnf.global_5.5
> >  #
> >  # special stuff for this host is below, brought to you by chef partial 
> > template:
> >  [mysqld]
> >  expire_logs_days=5
> >  replicate-wild-ignore-table = foo_bar.KBToyAndHobby%
> >
> >
> > The template resource in the recipe:
> >
> >  template "/etc/mysql/my.cnf" do
> >    source "my.cnf.erb"
> >    owner "root"
> >    group "root"
> >    mode 00644
> >    variables :server_id     => node['tokopf-bar']['mysql']['server_id'],
> >              :mysql_version => 
> > node['tokopf-bar']['mysql']['mysql_version']
> >  end
> >
> >
> > The main template, my.cnf.erb:
> >  [mysqld]
> >  server-id = <%= @server_id %>
> >  report-host = <%= node['fqdn'] %>
> >  !include /etc/mysql/_my.cnf_<%= node['ec2']['instance_type'] %>
> >  !include /etc/mysql/_my.cnf.global_<%= @mysql_version %>
> >  <%= render @node['fqdn'] + ".mycnf-partial.erb" -%>
> >
> >
> > cookbooks/tokopf-bar/templates/default/db14b.dev.example.com.mycnf-partial.erb
> >  is empty...
> >
> > cookbooks/tokopf-bar/templates/default/db26b.dev.example.com.mycnf-partial.erb:
> >  #
> >  # special stuff for this host is below, brought to you by chef partial 
> > template:
> >  [mysqld]
> >  expire_logs_days=5
> >  replicate-wild-ignore-table = foo_bar.KBToyAndHobby%
> >
> >
> > Thanks!
> > kallen
> >
>