fb_collectd: Fix various problems (facebook#261)

Summary:
* Most configs are not possible with existing code as it quotes strings
  that collectd won't accept quoted
* Add support for Load configurations
* Fix 'global' vs 'globals' in docs
* Add more docs

Signed-off-by: Phil Dibowitz <phil@ipom.com>

Pull Request resolved: facebook#261

Test Plan:
Imported from GitHub, without a `Test Plan:` line.

This cookbook is an open-source example, not in use internally.

Differential Revision: D69599764

fbshipit-source-id: 6fe4531662f906404377867beca18af3c470471f

Author: jaymzh

cookbooks/fb_collectd/README.md

@@ -15,25 +15,75 @@ Attributes
 
 Usage
 -----
-### Daemon
+### Daemon configuration
+
 To install collectd include `fb_collectd::default`. Global settings can be
 customized using the `node['fb_collectd']['globals']` attribute and individual
 plugins can be enabled and configured using `node['fb_collectd']['plugins']`.
 Example:
 
 ```ruby
-node.default['fb_collectd']['global']['FQDNLookup'] = true
+node.default['fb_collectd']['globals']['FQDNLookup'] = true
 node.default['fb_collectd']['plugins']['cpu'] = nil
 node.default['fb_collectd']['plugins']['syslog'] = {
   'LogLevel' => 'info',
 }
 ```
 
+This will render like:
+
+```text
+FQDNLookup true
+LoadPlugin cpu
+LoadPlugin syslog
+<Plugin syslog>
+  LogLevel info
+</Plugin>
+```
+
+All plugins will also be loaded with a simple `LoadPlugin $PLUGIN` - if you
+need the loading to have a configuration as well, use the `_load_config` key:
+
+```ruby
+node.default['fb_collectd']['plugins']['python'] => {
+  '_load_config' => {
+    'Globals' => true,
+  },
+  ...
+}
+```
+
+which will render like so:
+
+```text
+<LoadPlugin python>
+  Globals true
+</LoadPlugin>
+<Plugin python>
+  ...
+</Plugin>
+```
+
+Note that since collectd expects _most_ of its string config values to be unquoted,
+we do not quote string values by default (otherwise things like `LogLevel` above
+would error). If a value needs to be quoted, you can quote it in it's config:
+
+```ruby
+node.default['fb_collectd']['plugins']['apache'] => {
+  'Instance "localhost"' => {
+    'URL' => '"http://localhost/server-status?auto"',
+  },
+}
+```
+
+### Sysconfig
+
 On Debian systems, environment settings can be configured in
 `node['fb_collectd']['sysconfig']`; note that this attribute is ignored on
 CentOS.
 
 ### Frontend
+
 The collectd-web fronted can be installed with the `fb_collectd::fronted`
 recipe. Use the `node['fb_collectd']['collection']` to customize its settings.
 Note that this recipe will not install or configure a web server, so unless you

cookbooks/fb_collectd/libraries/default.rb

@@ -48,10 +48,8 @@ def self._gen_collectd_conf_entry(k, v, i = 0)
         return "#{indent}#{k} true"
       elsif v.is_a?(FalseClass)
         return "#{indent}#{k} false"
-      elsif v.is_a?(Numeric)
-        return "#{indent}#{k} #{v}"
       else
-        return "#{indent}#{k} \"#{v}\""
+        return "#{indent}#{k} #{v}"
       end
     end
   end

cookbooks/fb_collectd/templates/default/collectd.conf.erb

@@ -7,10 +7,19 @@
 <% end -%>
 
 <% config['plugins'].each do |plugin, config| -%>
+<%   if config && config['_load_config'] %>
+<LoadPlugin <%= plugin %>>
+<%     config['_load_config'].each do |key, val| %>
+<%=      FB::Collectd._gen_collectd_conf_entry(key, val, 1) %>
+<%     end %>
+</LoadPlugin>
+<%   else %>
 LoadPlugin <%= plugin %>
+<%   end %>
 <%   if config -%>
 <Plugin <%= plugin %>>
 <%     config.each do |key, val| -%>
+<%       next if key == '_load_config' %>
 <%=      FB::Collectd._gen_collectd_conf_entry(key, val, 2) %>
 <%     end -%>
 </Plugin>