option to manage journald config with dropin

Differential Revision: D73479410

fbshipit-source-id: 7f8fb9adab4a9ca36a4640470ba98e9dbd90aa65

Author: wujj123456

cookbooks/fb_systemd/README.md

@@ -14,6 +14,7 @@ Attributes
 * node['fb_systemd']['udevd']['hwdb']
 * node['fb_systemd']['udevd']['rules']
 * node['fb_systemd']['journald']['config']
+* node['fb_systemd']['journald']['manage_config_with_dropin']
 * node['fb_systemd']['journal-gatewayd']['enable']
 * node['fb_systemd']['journal-remote']['enable']
 * node['fb_systemd']['journal-remote']['config']
@@ -273,6 +274,10 @@ configure journald to use the 'auto' storage (disk if the log directory exists,
 or ram otherwise, which is the default for most distros). You can change these
 settings and more through `node['fb_systemd']['journald']['config']`.
 
+If `node['fb_systemd']['journald']['manage_config_with_dropin']` is `true`, a
+dropin will be used to implement the journald config. If `false`, chef
+overwrites `/etc/systemd/journald.conf` directly.
+
 Refer to the
 [journald documentation](https://www.freedesktop.org/software/systemd/man/journald.conf.html)
 for more details on possible configurations.

cookbooks/fb_systemd/attributes/default.rb

@@ -92,6 +92,7 @@
     'config' => {
       'Storage' => 'auto',
     },
+    'manage_config_with_dropin' => false,
   },
   'journal-gatewayd' => {
     'enable' => false,

cookbooks/fb_systemd/recipes/journald.rb

@@ -18,7 +18,19 @@
 # limitations under the License.
 #
 
-template '/etc/systemd/journald.conf' do
+if node['fb_systemd']['journald']['manage_config_with_dropin']
+  directory '/etc/systemd/journald.conf.d' do
+    owner node.root_user
+    group node.root_group
+    mode '0644'
+    action :create
+  end
+  journald_conf = '/etc/systemd/journald.conf.d/90-chef.conf'
+else
+  journald_conf = '/etc/systemd/journald.conf'
+end
+
+template journald_conf do
   source 'systemd.conf.erb'
   owner node.root_user
   group node.root_group