Adds some information about using in a Docker container

Fixes #61

Signed-off-by: Ed Robinson <[email protected]>

Author: errm

README.md

@@ -98,9 +98,6 @@ _Required_
 
 A tag that will be added to events generated by this input.
 
-### Example
-
-For an example of a full working setup including the plugin, [take a look at](https://github.com/assemblyline/fluentd)
 
 ## Filter Plugin Configuration
 
@@ -184,11 +181,38 @@ Typically you would not be able to this, so another way is to configure your log
 
 Another strategy would be to use a plugin like [fluent-plugin-concat](https://github.com/fluent-plugins-nursery/fluent-plugin-concat) to combine multi line logs into a single event, this is more tricky though because you need to be able to identify the first and last lines of a multi line message with a regex.
 
+> ### How can I use this plugin inside of a docker container ?
+
+* Install the [systemd dependencies](#dependencies) if required
+* You can use an [offical fluentd docker](https://github.com/fluent/fluentd-docker-image) image as a base, (choose the debian based version, as alpine linux doesn't support systemd).
+* Bind mount `/var/log/journal` into your container.
+
+### Example
+
+For an example of a full working setup including the plugin, take a look at [the fluentd kubernetes daemonset](https://github.com/fluent/fluentd-kubernetes-daemonset)
 
 ## Dependencies
 
 This plugin depends on libsystemd
 
+On Debian or Ubuntu you might need to install the libsystemd0 package:
+
+```
+apt-get install libsystemd0
+```
+
+On CentOS or RHEL you might need to install the systemd package:
+
+```
+yum install -y systemd
+```
+
+If you want to do this in a CentOS docker image you might first need to remove the `fakesystemd` package.
+
+```
+yum remove -y fakesystemd
+```
+
 ## Running the tests
 
 To run the tests with docker on several distros simply run `rake`