Streaming app logs with Fluentd

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Fluentd is an open source log collector that allows you to implement unified logging layers. With Fluentd, you can stream app logs to different back ends or services like Elasticsearch, HDFS and Amazon S3. This topic explains how to integrate Fluentd with Cloud Foundry apps.

Step 1: Create a Cloud Foundry syslog drain for Fluentd

1. In Cloud Foundry, create a syslog drain user-provided service instance as described in Using third-party log management services.

2. Choose one or more apps whose logs you want to drain to Fluentd through the service.

3. Bind each app to the service instance, and restart the app.

4. Note the GUID for each app, the IP address of the Loggregator host, and the port number for the service.

5. Locate the port number in the syslog URL. For example:

   syslog://logs.example.com:5140

Step 2: Set up Fluentd for Cloud Foundry

To continue, you must have an active Fluentd instance running. If you do not have an active Fluentd instance, see the Fluentd documentation for more details. If you use cf to deploy your fluentd instances, you have to use tcp routing.

Fluentd comes with native support for syslog protocol. To set up Fluentd for Cloud Foundry, configure the syslog input of Fluentd as follows.

1. In your main Fluentd configuration file, add the following source entry:

   <source>
     @type syslog
     port 8080
     bind 0.0.0.0
     tag cf.app
     message_length_limit 99990
     frame_type octet_count
     <transport tcp>
     </transport>
     <parse>
       message_format rfc5424
     </parse>
   </source>
   

2. Restart the Fluentd service.

The Fluentd syslog input plug-in supports tls and tcp options. You must use the same transport that Cloud Foundry is using.

Fluentd starts listening for syslog message on port 8080 and tagging the messages with cf.app, which can be used later for data routing. For more details about the full setup for the service, see Config File.

To use an Elasticsearch or Amazon S3 back end, see the Fluentd documentation.