Make client settings match server settings and improve docs (#189)

As described in issue #198, make settings in the client configs (E.G.
`auth`, `cipher`, `compress`, etc) match their server counterparts. This
eliminates warnings in the OpenVPN log about inconsistent option usage.

In addition, document how the `openvpn_user` resource works, including
showing how aditional configuration options can be added to client conf
files (using `additional_vars` and `cookbook_user_conf`)

Squashed commit of the following:

commit dab2949
Author: Josh Gitlin <[email protected]>
Date:   Fri May 14 14:33:29 2021 -0400

    Cookstyle fixes

commit d587ae1
Author: Josh Gitlin <[email protected]>
Date:   Fri May 14 14:31:33 2021 -0400

    MDL fixes

commit eda83e5
Author: Josh Gitlin <[email protected]>
Date:   Fri May 14 12:05:37 2021 -0400

    Added documentation for vpn_user resource

commit 61172d8
Author: Josh Gitlin <[email protected]>
Date:   Thu May 13 21:48:09 2021 -0400

    Make client settings match server settings

commit c14d15a
Author: Josh Gitlin <[email protected]>
Date:   Tue May 11 21:36:18 2021 -0400

    Add compression to client configs

Signed-off-by: Josh Gitlin <[email protected]>

README.md

@@ -58,7 +58,7 @@ These attributes are set by the cookbook by default.
 - `node['openvpn']['configure_default_server']` - Boolean. Set this to false if you want to create all of your "conf" files with the LWRP.
 - `node['openvpn']['git_package']` - Boolean. Whether to use the `openvpn-git` package (Arch Linux only, default false).
 - `node['openvpn']['client_prefix']` - String. Name of the config that is created for clients. When imported into most vpn clients, this is the name that will be displayed for the connection. Default is 'vpn-prod'.
-- `node['openvpn']['cookbook_user_conf']` - String. The cookbook used by the `openvpn::users` recipe for the `client.conf.erb` template. You can override this to your own, such as your wrapper cookbook. Default is `'openvpn'`.
+- `node['openvpn']['cookbook_user_conf']` - String. The cookbook used by the `openvpn::users` recipe for the `client.conf.erb` template. You can override this to your own, such as your wrapper cookbook. Default is `'openvpn'`. See [Customizing user configuration](#customizing-user-configuration) under the [openvpn_user resource](#openvpn_user) section
 - `node['openvpn']['key_dir']` - Location to store keys, certificates and related files. Default `/etc/openvpn/keys`.
 - `node['openvpn']['signing_ca_cert']` - CA certificate for signing, default `/etc/openvpn/keys/ca.crt`
 - `node['openvpn']['signing_ca_key']` - CA key for signing, default `/etc/openvpn/keys/ca.key`
@@ -198,7 +198,54 @@ This cookbook also provides an 'up' script that runs when OpenVPN is started. Th
 
 ### openvpn_user
 
-Implements a resource for creation of users and bundles.
+Implements a resource for creation of users and bundles. User configuration will attempt to match the server configuration as best as possible,
+by matching node attributes like `node['openvpn']['config']['compress']` and `node['openvpn']['config']['cipher']`. Reasonable default configuration
+for the user bundle is specified otherwise.
+
+By default, an OpenVPN user _bundle_ is created, which is a gzipped TAR file (`.tgz` archive) containing the user configuration and the public/private
+keys. This is controlled by the `create_bundle` attribute of the `openvpn_user` resource; pass `create_bundle false` if you prefer to have inline `.ovpn`
+files created, containing the public and private keys all inside one OpenVPN config file.
+
+#### Customizing user configuration
+
+If the provided OpenVPN configuration does not meet your needs, either because you need different configuration directives, or you want to add directives which
+are not present, you can use the node attribute `node['openvpn']['cookbook_user_conf']` to look for the template files in a different cookbook, E.G. in your
+wrapper cookbook.
+
+If you only need _additional_ directives, you can use the `additional_vars` attribute of the `openvpn_user` resource to pass additional template variables to your
+custom template. This way, you can render the user configuration from this cookbook using a partial, and append (or prepend) your own config inside your template.
+
+#### Example
+
+Adding a 2FA via a hardware token
+
+`cookbooks/vpn_wrapper/recipes/user.rb`:
+
+```ruby
+override["openvpn"]["cookbook_user_conf"] => "vpn_wrapper"
+openvpn_user "VPN User Bundle" do
+  client_name "my_user"
+  additional_vars(
+    static_challenge: %{"Touch your hardware token now:" 0}
+  )
+end
+```
+
+`cookbooks/vpn_wrapper/templates/client.conf.erb`:
+
+```ruby
+<%= render "client.conf.erb", cookbook: "openvpn" %>
+auth-user-pass
+static-challenge <%= @static_challenge %>
+```
+
+`cookbooks/vpn_wrapper/templates/client-inline.conf.erb`:
+
+```ruby
+<%= render "client-inline.conf.erb", cookbook: "openvpn" %>
+auth-user-pass
+static-challenge <%= @static_challenge %>
+```
 
 ### openvpn_config
 

resources/user.rb

@@ -22,6 +22,11 @@
   destination_path = ::File.expand_path(new_resource.destination || key_dir)
   bundle_filename = "#{new_resource.client_name}.tar.gz"
   bundle_full_path = ::File.expand_path(::File.join(destination_path, bundle_filename))
+  compression = if node['openvpn']['config']['compress']
+                  node['openvpn']['config']['compress']
+                elsif default['openvpn']['config']['comp-lzo']
+                  'lzo'
+                end
 
   execute "generate-openvpn-#{new_resource.client_name}" do
     command "./pkitool #{new_resource.client_name}"
@@ -46,15 +51,15 @@
 
   template "#{destination_path}/#{client_file_basename}.conf" do
     source 'client.conf.erb'
-    cookbook node['openvpn']['cookbook_user_conf']
+    cookbook lazy { node['openvpn']['cookbook_user_conf'] }
     variables(client_cn: new_resource.client_name)
     notifies :delete, "file[#{cleanup_name}]", :immediately
     only_if { new_resource.create_bundle }
   end
 
   template "#{destination_path}/#{client_file_basename}.ovpn" do
     source new_resource.create_bundle ? 'client.conf.erb' : 'client-inline.conf.erb'
-    cookbook node['openvpn']['cookbook_user_conf']
+    cookbook lazy { node['openvpn']['cookbook_user_conf'] }
     if new_resource.create_bundle
       variables(client_cn: new_resource.client_name)
     else
@@ -66,6 +71,7 @@
             ca: IO.read(ca_cert_path),
             cert: IO.read(cert_path),
             key: IO.read(key_path),
+            compression: compression,
           }.merge(new_resource.additional_vars) { |key, oldval, newval| oldval } # rubocop:disable Lint/UnusedBlockArgument
         end
       )

templates/client-inline.conf.erb

@@ -12,7 +12,17 @@ resolv-retry infinite
 nobind
 persist-key
 persist-tun
-comp-lzo
+<% if @compression -%>
+compress <%= @compression %>
+<% end %>
+<% 
+%w(cipher tls-cipher auth keysize link-mtu).each do |conf| 
+  if node['openvpn']['config'][conf]
+%><%= "#{conf} #{node['openvpn']['config'][conf]}" %>
+<%
+  end
+end 
+-%>
 verb 3
 <ca>
 <%= @ca -%>

templates/client.conf.erb

@@ -15,8 +15,18 @@ persist-tun
 ca ca.crt
 cert <%= @client_cn %>.crt
 key <%= @client_cn %>.key
-comp-lzo
+<% if @compression -%>
+<%= @compression %>
+<% end %>
+<% 
+%w(cipher tls-cipher auth keysize link-mtu).each do |conf| 
+  if node['openvpn']['config'][conf]
+%><%= "#{conf} #{node['openvpn']['config'][conf]}" %>
+<%
+  end
+end 
+-%>
 verb 3
-<% if node['openvpn']['server_verification'] %>
+<% if node['openvpn']['server_verification'] -%>
 <%= node['openvpn']['server_verification'] %>
-<% end %>
+<% end -%>