View flow logs in the Calico Whisker web console

note

This feature is tech preview. Tech preview features may be subject to significant changes before they become GA.

You can observe network traffic in your cluster by viewing flow logs in the Calico Whisker web console.

About flow logs in Calico Open Source

Tracking network activity in your cluster is essential for understanding how your applications communicate. Calico helps you see your network activity by processing your network connections and recording them in a digestible format called a flow log.

A flow log is an aggregation of connection data that matches the same set of criteria (i.e., source, destination, policies) across your cluster over a period of time. Flow logs don't record every single network connection that takes place in your cluster. Rather, they represent a type of network flow that occurs in your cluster. Imagine, for example, that your cluster has 1000 individual network connections that take place within 1 minute. It would be difficult to sort through those 1000 connections, and more difficult to understand what they mean. But the corresponding flow logs for that minute might turn those 1000 entries into 15 flow logs, each representing a distinct type of connection (pod A to pod B, public internet to pod C), but without the duplicate flow type entries. This way, you can understand the overall network activity without being overwhelmed by the sheer volume of data.

Using flow logs

Flow logs are useful for a variety of purposes, including:

• Network visibility. Understanding traffic patterns within the cluster, between namespaces, and to or from external services.
• Troubleshooting connectivity issues. If pods aren't communicating, flow logs can show if traffic is being denied by policy or if it's actually reaching the destination.
• Security. Detecting policy violations (unexpected deny logs), identifying anomalous traffic patterns (e.g., unusually high data transfer), and investigating potential security incidents.
• Policy validation. Confirming that network policies are working as intended (allowing expected traffic, denying forbidden traffic). This is especially useful for testing out staged network policies before moving them to production.

Calico Whisker

The Calico Whisker web console is a browser-based interface that shows you a stream of flow logs from your cluster in real time. While the console is open, it receives live data from a dedicated flow logs API (Goldmane). You can filter the stream to see only the logs for a particular policy, namespace, pod, or other criteria.

Figure 1. A view of the Calico Whisker web console showing flow logs in a Kubernetes cluster.

Flow log data types

The following table describes the flow log data types used by Calico Whisker.

Name	Datatype	Description
start_time	date	Start time of log collection in UNIX timestamp format.
end_time	date	End time of log collection in UNIX timestamp format.
action	keyword	- allow: Calico accepted the flow. - deny: Calico denied the flow.
bytes_in	long	Number of incoming bytes within the timeframe.
bytes_out	long	Number of outgoing bytes within the timeframe.
dest_name	keyword	Contains one of the following values: - Name of the destination pod. - Name of the pod that was aggregated or the endpoint is not a pod.
dest_namespace	keyword	Namespace of the destination endpoint. A - means the endpoint is not namespaced.
dest_port	long	Destination port. Not applicable for ICMP packets.
dest_labels	array of keywords	Labels applied to the destination pod.
reporter	keyword	- src: flow came from the source that initiated the connection. - dst: flow came from the destination that received the initial connection.
packets_in	long	Number of incoming packets within the timeframe.
packets_out	long	Number of outgoing packets within the timeframe.
protocol	keyword	Protocol.
policies	array of arrays	List of policies that interacted with this flow.
source_name	keyword	Contains one of the following values: - Name of the source pod. - Name of the pod that was aggregated or the endpoint is not a pod. Check source_name_aggr for more information, such as the name of the pod if it was aggregated.
source_namespace	keyword	Namespace of the source endpoint. A - means the endpoint is not namespaced.
source_labels	array of keywords	Labels applied to the source pod. A hyphen indicates aggregation.

View flow logs in the web console

You can quickly view flow logs by port forwarding the Calico Whisker web console to your workstation. By default, Whisker does not automatically expose an endpoint.

Prerequisites

• You have kubectl access to a Kubernetes cluster with Calico installed.
• Calico Whisker and the flow logs API are enabled on your cluster. For new installations, they're both enabled by default. If you upgraded from Calico Open Source 3.29 or earlier, you need to enable them manually.

Procedure

1. Port forward the Calico Whisker web console to your workstation:

   kubectl port-forward -n calico-system service/whisker 8081:8081
   Expected output

   Forwarding from 127.0.0.1:8081 -> 8081
   Forwarding from [::1]:8081 -> 8081

2. To open Calico Whisker, open your browser and go to localhost:8081. You may not see any flows at the beginning. But in a few moments, as the console receives data, you'll begin to see a list of flow logs.

Additional resources

• To use flow logs in your own scripts or applications, see Flow logs API.
• For more free observability tools, try Calico Cloud Free.
• How to get started with Calico Observability features blog.
• Click here to try Kubernetes observability in your browser right now.
• Learn everything about Calico Whisker from this video presentation.