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Flows and ClusterFlows

See the Logging operator documentation for the full details on how to configure Flows and ClusterFlows.

See Rancher Integration with Logging Services: Troubleshooting for how to resolve memory problems with the logging buffer.


A Flow defines which logs to collect and filter and which output to send the logs to.

The Flow is a namespaced resource, which means logs will only be collected from the namespace that the Flow is deployed in.

Flows can be configured by filling out forms in the Rancher UI.

For more details about the Flow custom resource, see FlowSpec.


Match statements are used to select which containers to pull logs from.

You can specify match statements to select or exclude logs according to Kubernetes labels, container and host names. Match statements are evaluated in the order they are defined and processed only until the first matching select or exclude rule applies.

Matches can be configured by filling out the Flow or ClusterFlow forms in the Rancher UI.

For detailed examples on using the match statement, see the official documentation on log routing.


You can define one or more filters within a Flow. Filters can perform various actions on the logs, such as adding data, transforming the logs, or parsing values from the records. The filters in the Flow are applied in the same order they appear in the definition.

For a list of filters supported by the Logging operator, see the official documentation on Fluentd filters.

Filters need to be configured in YAML.


This Output will receive logs from the Flow. Because the Flow is a namespaced resource, the Output must reside in same namespace as the Flow.

Outputs can be referenced when filling out the Flow or ClusterFlow forms in the Rancher UI.


Matches, filters and Outputs are configured for ClusterFlows in the same way that they are configured for Flows. The key difference is that the ClusterFlow is scoped at the cluster level and can configure log collection across all namespaces.

ClusterFlows can be configured by filling out forms in the Rancher UI.

After ClusterFlow selects logs from all namespaces in the cluster, logs from the cluster will be collected and logged to the selected ClusterOutput.

YAML Example

The following example Flow transforms the log messages from the default namespace and sends them to an S3 Output:

kind: Flow
name: flow-sample
namespace: default
- parser:
remove_key_name_field: true
type: nginx
- tag_normaliser:
format: ${namespace_name}.${pod_name}.${container_name}
- s3-output
- select:
app: nginx