Configure logs for Kubernetes 🔗

Note

See how to configure the Collector for Kubernetes at Configure Helm for Kubernetes and Advanced configuration for Kubernetes.

The Helm chart currently uses Fluentd for Kubernetes logs collection. Logs collected with Fluentd are sent through the Collector agent, which does all of the necessary metadata enrichment.

Add the following line to your configuration to use OpenTelemetry logs collection instead of Fluentd:

logsEngine: otel

The following are known limitations of native OpenTelemetry logs collection:

The service.name attribute is not automatically constructed in an Istio environment, which means that correlation between logs and traces does not work in Splunk Observability Cloud. Use Fluentd for logs collection if you deploy the Helm chart with autodetect.istio=true.
Journald logs cannot be natively collected by the Collector at this time.
Logs collection is not supported in GKE Autopilot at this time.
See also other rules and limitations for metrics and dimensions. For instance, you can have up to 36 dimensions per MTS, otherwise the data point is dropped.

Add log files from Kubernetes host machines or volumes 🔗

Add additional log files to be ingested from Kubernetes host machines and Kubernetes volumes by configuring agent.extraVolumes, agent.extraVolumeMounts, and logsCollection.extraFileLogs in the values.yaml file used to deploy the Collector for Kubernetes.

The following example shows how to add logs from Kubernetes host machines:

logsCollection:
  extraFileLogs:
    filelog/audit-log:
      include: [/var/log/kubernetes/apiserver/audit.log]
      start_at: beginning
      include_file_path: true
      include_file_name: false
      resource:
        com.splunk.source: /var/log/kubernetes/apiserver/audit.log
        host.name: 'EXPR(env("K8S_NODE_NAME"))'
        com.splunk.sourcetype: kube:apiserver-audit
agent:
  extraVolumeMounts:
    - name: audit-log
      mountPath: /var/log/kubernetes/apiserver
  extraVolumes:
    - name: audit-log
      hostPath:
        path: /var/log/kubernetes/apiserver

Process multi-line logs 🔗

The Splunk Distribution of OpenTelemetry Collector for Kubernetes supports parsing of multi-line logs to help read, understand, and troubleshoot the multi-line logs in a better way. Process multi-line logs by adding the following section to your values.yaml configuration:

logsCollection:
  containers:
    multilineConfigs:
      - namespaceName:
          value: default
        podName:
          value: buttercup-app-.*
          useRegexp: true
        containerName:
          value: server
          firstEntryRegex: ^[^\s].*

Use regex101 to find a golang regex that works for your format and specify it in the config file for the config option firstEntryRegex.

Collect journald events 🔗

The Splunk Distribution of OpenTelemetry Collector for Kubernetes can collect journald events from Kubernetes environment. Process journald events by adding the following section to your values.yaml configuration:

logsCollection:
  journald:
    enabled: true
    directory: /run/log/journal
    # List of service units to collect and configuration for each. Update the list as needed.
    units:
      - name: kubelet
        priority: info
      - name: docker
        priority: info
      - name: containerd
        priority: info
    # Optional: Route journald logs to a separate Splunk Index by specifying the index
    # value. Make sure the index exists in Splunk and is configured to receive HEC
    # traffic (not applicable to Observability Cloud).
    index: ""

Manage log ingestion using annotations 🔗

The following annotations for log ingestion management are supported:

Use the splunk.com/index annotation on pods and/or namespaces to indicate which Splunk platform indexes you want to send logs to. Pod annotation will take precedence over namespace annotation when both are annotated.
- For example, to send logs from the kube-system namespace to the k8s_events index, use the command:
```
kubectl annotate namespace kube-system splunk.com/index=k8s_events
```
Filter logs using pod and/or namespace annotations:
- If logsCollection.containers.useSplunkIncludeAnnotation is false (default value), set the splunk.com/exclude annotation to true on pods and/or namespaces to exclude their logs from being ingested.
- If logsCollection.containers.useSplunkIncludeAnnotation is true, set the splunk.com/include annotation to true on pods and/or namespaces to only ingest their logs. All other logs will be ignored.
Use the splunk.com/sourcetype annotation on a pod to overwrite the sourcetype field. If not set, it will default to kube:container:CONTAINER_NAME.

Review performance benchmarks 🔗

Some configurations used with the OpenTelemetry Collector (as set using the Collector for Kubernetes Helm chart) can have an impact on overall performance of log ingestion. The more receivers, processors, exporters, and extensions that are added to any of the pipelines, the greater the performance impact.

The Splunk Distribution of OpenTelemetry Collector for Kubernetes can exceed the default throughput of the HTTP Event Collector (HEC). To address capacity needs, monitor the HEC throughput and back pressure on the Collector for Kubernetes deployments and be prepared to add additional nodes as needed.

The following table provides a summary of performance benchmarks run internally:

Performance benchmarks 🔗
Log generator count	Event size (byte)	Agent CPU usage	Agent EPS
1	256	1.8	30,000
1	516	1.8	28,000
1	1024	1.8	24,000
5	256	3.2	54,000
7	256	3	52,000
10	256	3.2	53,000

The data pipelines for these test runs involved reading container logs as they are being written, then parsing filename for metadata, enriching it with Kubernetes metadata, reformatting the data structure, and sending logs (without compression) to the Splunk HEC endpoint.

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