Kubernetes: a monitoring guide

Today’s post is by Jean-Mathieu Saponaro, Research & Analytics Engineer at Datadog, discussing what Kubernetes changes for monitoring, and how you can prepare to properly monitor a containerized infrastructure orchestrated by Kubernetes.

Container technologies are taking the infrastructure world by storm. While containers solve or simplify infrastructure management processes, they also introduce significant complexity in terms of orchestration. That’s where Kubernetes comes to our rescue. Just like a conductor directs an orchestra, Kubernetes oversees our ensemble of containers—starting, stopping, creating, and destroying them automatically to keep our applications humming along.

Kubernetes makes managing a containerized infrastructure much easier by creating levels of abstractions such as pods and services. We no longer have to worry about where applications are running or if they have enough resources to work properly. But that doesn’t change the fact that, in order to ensure good performance, we need to monitor our applications, the containers running them, and Kubernetes itself.

Rethinking monitoring for the Kubernetes era

Just as containers have completely transformed how we think about running services on virtual machines, Kubernetes has changed the way we interact with containers. The good news is that with proper monitoring, the abstraction levels inherent to Kubernetes provide a comprehensive view of your infrastructure, even if the containers and applications are constantly moving. But Kubernetes monitoring requires us to rethink and reorient our strategies, since it differs from monitoring traditional hosts such as VMs or physical machines in several ways.

Tags and labels become essential
With containers and their orchestration completely managed by Kubernetes, labels are now the only way we have to interact with pods and containers. That’s why they are absolutely crucial for monitoring since all metrics and events will be sliced and diced using labels across the different layers of your infrastructure. Defining your labels with a logical and easy-to-understand schema is essential so your metrics will be as useful as possible.

There are now more components to monitor

In traditional, host-centric infrastructure, we were used to monitoring only two layers: applications and the hosts running them. Now with containers in the middle and Kubernetes itself needing to be monitored, there are four different components to monitor and collect metrics from.

Applications are constantly moving
Kubernetes schedules applications dynamically based on scheduling policy, so you don’t always know where applications are running. But they still need to be monitored. That’s why using a monitoring system or tool with service discovery is a must. It will automatically adapt metric collection to moving containers so applications can be continuously monitored without interruption.

Be prepared for distributed clusters

Kubernetes has the ability to distribute containerized applications across multiple data centers and potentially different cloud providers. That means metrics must be collected and aggregated among all these different sources. 

For more details about all these new monitoring challenges inherent to Kubernetes and how to overcome them, we recently published an in-depth Kubernetes monitoring guide. Part 1 of the series covers how to adapt your monitoring strategies to the Kubernetes era.

Metrics to monitor

Whether you use Heapster data or a monitoring tool integrating with Kubernetes and its different APIs, there are several key types of metrics that need to be closely tracked:

• Running pods and their deployments
• Usual resource metrics such as CPU, memory usage, and disk I/O
• Container-native metrics
• Application metrics for which a service discovery feature in your monitoring tool is essential 

All these metrics should be aggregated using Kubernetes labels and correlated with events from Kubernetes and container technologies.

Part 2 of our series on Kubernetes monitoring guides you through all the data that needs to be collected and tracked.

Collecting these metrics

Whether you want to track these key performance metrics by combining Heapster, a storage backend, and a graphing tool, or by integrating a monitoring tool with the different components of your infrastructure, Part 3, about Kubernetes metric collection, has you covered.

Anchors aweigh!

Using Kubernetes drastically simplifies container management. But it requires us to rethink our monitoring strategies on several fronts, and to make sure all the key metrics from the different components are properly collected, aggregated, and tracked. We hope our monitoring guide will help you to effectively monitor your Kubernetes clusters. Feedback and suggestions are more than welcome.

--Jean-Mathieu Saponaro, Research & Analytics Engineer, Datadog

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