Publish logs to Elasticsearch Using Fluentd


This page describes to how to configure a WebLogic domain to use Fluentd to send log information to Elasticsearch. Here’s the general mechanism for how this works:

  • fluentd runs as a separate container in the Administration Server and Managed Server pods
  • The log files reside on a volume that is shared between the weblogic-server and fluentd containers
  • fluentd tails the domain logs files and exports them to Elasticsearch
  • A ConfigMap contains the filter and format rules for exporting log records.

Create fluentd configuration

Create a ConfigMap named fluentd-config in the namespace of the domain. The ConfigMap contains the parsing rules and Elasticsearch configuration. Here’s an explanation of some elements defined in the ConfigMap:

  • The @type tail indicates that tail will be used to obtain updates to the log file
  • The path of the log file is obtained from the LOG_PATH environment variable that is defined in the fluentd container
  • The tag value of log records is obtained from the DOMAIN_UID environment variable that is defined in the fluentd container
  • The parse section defines how to interpret and tag each element of a log record
  • The match section contains the configuration information for connecting to Elasticsearch and defines the index name of each record to be the domainUID

Here is a sample configmap for fluentd configuration,

Click here to see sample configmap for fluentd configuration `fluentd_configmap.yaml`.

Create the ConfigMap using the following command

   $kubectl create -f fluentd_configmap.yaml 

Mount fluentd configuration - Configmap as volume in the WebLogic container.

Edit the domain definition and configure a volume for the ConfigMap containing the fluentd configuration.

   $kubectl edit domain -n wccns

Below sample yaml code add Configmap as volume,

- name: weblogic-domain-storage-volume
    claimName: wccinfra-domain-pvc
- configMap:
    defaultMode: 420
    name: fluentd-config
  name: fluentd-config-volume

Add fluentd container to WebLogic Server pods

Add a “fluentd container yaml” to the domain under serverPod: section that will run fluentd in the Administration Server and Managed Server pods.

Notice the container definition:

  • Defines a LOG_PATH environment variable that points to the log location of WebLogic servers.
  • Has volume mounts for the fluentd-config ConfigMap and the volume containing the domain logs.
   $kubectl edit domain -n wccns
Click here to see sample fluentd container yaml `fluentd container`.

Restart WebLogic Servers

To restart the servers, edit the domain and change serverStartPolicy to NEVER for the WebLogic servers to shutdown

   $kubectl edit domain -n wccns

After all the servers are shutdown edit domain again and set serverStartPolicy to IF_NEEDED for the servers to start again.

Create index pattern in Kibana

Create an index pattern “wccinfra*” in Kibana > Management. After the server starts, you will be able to see the log data in the Kibana dashboard,