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A Deep Dive in Kubernetes Metrics

January 23, 2024 | 12 min read

In the rapidly evolving landscape of cloud computing, Kubernetes has emerged as a pivotal force in container orchestration, revolutionizing how applications are deployed, scaled, and managed. As Kubernetes environments grow in complexity, the challenges in efficiently managing resources, ensuring optimal performance, and maintaining system health become more challenging.

This article will look at the various Kubernetes metrics, their significance, and their use cases to optimize resource usage, identify problems, and implement auto-scaling techniques. Understanding these metrics is key to unlocking the full potential of your Kubernetes deployments.

What are the Benefits of Kubernetes Monitoring?

A Kubernetes cluster consists of two major types of nodes: Worker nodes and Control Plane nodes. The Worker nodes are nodes used to run containerized workloads.

The Control Plane nodes manage and maintain a record of clusters through centralized APIs and internal services.

Using a Kubernetes monitoring strategy for your clusters has numerous advantages, such as:

  • Reliability - Kubernetes can be unreliable due to its complexity and difficulty in determining the underlying source of problems, especially if they are cloud-based or implement a microservices architecture. Monitoring tools can provide you with visibility into your Kubernetes setup so you can identify potential problem areas and take corrective action.
  • Performance improvement - Monitoring tools enable you to choose your hardware configurations and run apps faster and more efficiently. This is made possible by knowing the ins and outs of a Kubernetes cluster.
  • Managing Costs - Monitoring tools are crucial to keeping track of the resources you use. They help you know the number of your operational nodes, especially if your Kubernetes apps are hosted on a cloud infrastructure.
  • Resource attribution - Monitoring tools help to identify which teams and groups have used particular resources. The essential consumption data for cost analysis and chargeback purposes is provided via Kubernetes monitoring.

Resource Metrics

Resource metrics are essential for monitoring the health and performance of Kubernetes objects. Some essential resource metrics include CPU, memory, network, and disk usage. These metrics can help identify resource bottlenecks and optimize resource allocation to improve application performance.

Resource metrics can be classified into:

  • Cluster Metrics
  • Pod Metrics
  • State Metrics
  • Container
  • Application Metrics

Kubernetes Cluster Metrics

Monitoring the health of your Kubernetes cluster is crucial to understand the issues that affect its health. You may find out how many resources the cluster uses and how many applications run on each cluster node. You can also learn about your nodes' capacity and effectiveness.

Some critical metrics to monitor include the following;

  • Node resource usage: Metrics like disk utilization, memory and CPU usage, and network bandwidth. These indicators help you decide whether to change the size and number of cluster nodes.
  • Node count: This metric can show you how the cluster is used and what resources the cloud provider is billing you for.
  • Active pods: This metric allows you to track the number of active pods and determine whether the number of active nodes is adequate to handle the workloads in the event of a node failure.

Kubernetes Pod Metrics

Monitoring a Kubernetes pod can be broken down into three components:

  • Kubernetes metrics: These metrics let you track how the orchestrator manages and deploys each pod. You may keep track of data like the difference between the actual and expected number of instances in a pod at any particular time. Additionally, you may monitor network metrics, verify the health of your pods, and view in-progress deployment.
  • Pod container metrics: These are mostly accessible by cAdvisor and exposed by Heapster, which asks each node about the running containers. Network, CPU, and memory utilization are significant metrics that can be compared to the allowable maximum usage.
  • Application-specific metrics: These metrics come with an application and are related to particular business rules. For instance, a database application will provide relational statistics and metrics on the condition of an index. In contrast, an e-commerce platform may display information on the number of online users and the money made over a specific period. The program directly exposes these metrics, and you may connect the app to a monitoring tool to keep a closer eye on them.

State Metrics

State metrics check the state of Kubernetes objects, nodes, pods, DaemonSets, and namespaces. An example of such a metric is the kube-state-metrics.

Other elements that state metrics can monitor include:

  • Persistent Volumes (PVs): These are storage resources designated on the cluster and can be accessed as continuous storage for any pod that needs it. Throughout their lifespan, PVs remain attached to a specific pod. The PV is reclaimed once the pod no longer needs it. When reclamation attempts fail, indicating a persistent storage problem, you can find out by monitoring PVs.
  • Disk pressure: Disk pressure happens when a node consumes disk space too quickly or in excess. A programmable threshold is used to define disk pressure. By monitoring this metric, you can determine whether the application needs more disk space or if the disk fills up early and unexpectedly.
  • Crash loop: occurs when a pod launches, crashes, and then becomes caught in a cycle of repeatedly attempting to launch without success. The application cannot function while a crash loop takes place. A pod misconfiguration, a crashing program inside the pod, or a deployment problem could cause it. Debugging a crash loop can be challenging since many potential outcomes exist. To promptly minimize or execute emergency actions that keep the program operational, you must learn about the accident as soon as possible.
  • Jobs: are components designed to run pods temporarily for a limited time. After the pods have completed their work, the job can turn them off. However, sometimes, jobs fall short of fulfilling their intended purpose. This might occur as a result of a node crashing or rebooting. It could also be the outcome of resource depletion. You can find out whether your application is not accessible by keeping track of job failures. If successfully run, the job can shut down the pods after they've finished performing their tasks.

Container Metrics

Monitoring container metrics ensures containers properly utilize the cluster resources. These metrics can help you detect pods stuck in a CrashLoopBackoff and monitor your resource utilization and limits.

Some of the critical container metrics to monitor include the following:

  • Container CPU utilization: Find out how much of your containers' CPU resources are being used compared to the pod restrictions you've set.
  • Container memory consumption: Learn how much memory your containers are using compared to the pod restrictions you've set.
  • Network utilization: determine the bandwidth utilized and the number of data packets sent and received.

Application Metrics

These metrics can help you monitor the availability and performance of pod applications. The application's business scope is what determines the type of metrics provided. Some essential application metrics include:

  • Application availability: This can assist you in gauging the application's uptime and response times. You may evaluate the best user experience and performance using this metric.
  • Application health and performance: You can learn about performance problems, latency, responsiveness, and other user experience problems by monitoring the health and performance of your application. This measure might highlight application layer issues that need to be corrected

Custom Metrics

Equally crucial for tracking application performance are custom metrics. These measurements can shed light on performance measures that are exclusive to an application, like request latency, error rates, and throughput. You can find performance problems and improve application performance by tracking these indicators.

  • Demand Latency: The time it takes for an application to process a request is known as request latency. An application that experiences high request latency may be overloaded and need more resources.
  • Error Rates: Error rates quantify the proportion of unsuccessful requests. High error rates are a sign that an application is having problems and may need more resources.
  • Throughput: The quantity of requests an application responds to over time is measured by throughput. A well-performing application may not need more resources if it has a high throughput.

Kubernetes Metrics Tools

Kubernetes provides several tools for monitoring and analyzing metrics, including Prometheus, Grafana, and Kubernetes Dashboard. These tools assist in visualizing and analyzing metrics data, setting up alerts, and implementing auto-scaling strategies based on metric thresholds.

  • Prometheus: Prometheus is an open-source system that collects metrics data from Kubernetes objects and stores it in a time-series database. Prometheus provides a powerful query language that can be used to analyze metrics data and create custom alerts.
  • Grafana: Grafana is an open-source visualization tool enabling users to create dashboards that display metrics data from Prometheus. Grafana offers an extensive range of visualization options and the ability to make custom alerts depending on metric thresholds.
  • Kubernetes Dashboard: Kubernetes Dashboard is a web-based user interface that provides a graphical view of Kubernetes objects and their associated metrics. With Kubernetes Dashboard, you can monitor the health and performance of Kubernetes objects and diagnose upcoming issues.

Kubernetes Metrics Matter

Deployed software applications require constant monitoring and optimization to maintain good user interaction with the application. This is where Kubernetes metrics come in. Kubernetes provides developers with tools like Prometheus, Telepresence, Grafana, and the Kubernetes Dashboard to monitor and optimize Kubernetes objects and applications' performance. These tools can assist you in visualizing and analyzing metrics data, setting alarms, and implementing auto-scaling techniques depending on metric thresholds. Now that you have a solid understanding of how Kubernetes metrics work, what to look out for, and the tools that can help you along the way, it’s time to get started!