How to use the command 'k9s' (with examples)

K9s is a terminal-based interface for managing Kubernetes clusters. It allows users to navigate and control their Kubernetes resources with ease, using a slick, text-based UI. Its primary strength lies in simplifying Kubernetes management tasks by offering an easier and more efficient way to interact with complex cluster environments directly from the command line.

Use case 1: Manage a cluster using a kubeconfig context

Code:

k9s --context kubeconfig_context_name

Motivation: When managing Kubernetes clusters, it is common to deal with multiple clusters from different cloud providers or environments (development, staging, production). Each of these clusters is referred to as a “context” in your kubeconfig file. Having a tool like K9s that can easily switch between these contexts is highly beneficial for developers and administrators who work across numerous projects and need a streamlined method to access and manage their clusters. Using the specific context, you can ensure that the operations you perform are applied to the correct cluster, thereby minimizing the risk of accidentally executing commands on the wrong cluster.

Explanation:

• k9s: Launches the K9s application.
• --context kubeconfig_context_name: This argument specifies the context for the Kubernetes cluster configuration stored in your kubeconfig file. By setting this, K9s will target the specified context, which essentially points to a specific Kubernetes cluster and namespace configuration.

Example Output: Upon executing the command, K9s launches in the terminal with the user interface focused on the cluster specified by the context. You will see a dashboard presenting a high-level view of cluster resources, including pods, deployments, namespaces, nodes, and more, all belonging to the specified context.

Use case 2: Manage a cluster in read-only mode

Code:

k9s --readonly --cluster cluster_name

Motivation: Read-only access is essential for situations where users need to audit cluster states, view resource allocations, or conduct monitoring without the risk of altering any configuration or state. This mode is particularly useful for operations teams overseeing production environments where stability must be maintained, or for new team members who are learning about cluster dynamics without having the ability to introduce unintended changes.

Explanation:

• k9s: Initiates the K9s application interface.
• --readonly: This flag ensures that all potentially destructive commands are disabled. Users cannot perform any operations that modify the cluster state, guaranteeing a safe viewing environment.
• --cluster cluster_name: This specifies the target Kubernetes cluster to be accessed in read-only mode.

Example Output: The terminal interface will display information about the cluster, but interactive features for modifying resources will be disabled or unavailable, ensuring that no accidental changes can occur while still allowing full visibility of the cluster’s current state and configurations.

Use case 3: Manage a cluster using a given Kubernetes namespace

Code:

k9s --namespace kubernetes_namespace --cluster cluster_name

Motivation: Namespaces in Kubernetes provide an excellent way to partition cluster resources and separate concerns within the same cluster. When working in environments where multiple teams or projects run concurrently, focusing K9s on a specific namespace can help find relevant resources quickly without wading through the clutter of unrelated resources. This helps enhance productivity and provides a cleaner view tailored to the needs of specific tasks or projects.

Explanation:

• k9s: Starts the K9s terminal application.
• --namespace kubernetes_namespace: This option focuses the K9s interface on the specified namespace, filtering out resources that belong to other namespaces.
• --cluster cluster_name: This designates the desired cluster to manage or inspect, ensuring operations are correctly directed.

Example Output: When the command is run, K9s presents resources that only belong to the specified namespace within the selected cluster, offering a streamlined view that simplifies navigation and management tasks within that namespace alone.

Use case 4: Manage a cluster launching K9s in the pod view and enable debug logging

Code:

k9s --command pod --logLevel debug --cluster cluster_name

Motivation: Deep-diving into pod activities and debugging is frequent during the development and maintenance of cloud-native applications. Pods are fundamental units in Kubernetes, and being able to understand their behavior, logs, and errors is crucial. Enabling debug logging while focused on the pod view allows greater insight into potential issues. This setup is vital when troubleshooting or diagnosing the root cause of service problems in real-time.

Explanation:

• k9s: Initiates the K9s environment.
• --command pod: Directs K9s to immediately open in the pod view, which displays an in-depth list and details of pods currently running in the cluster.
• --logLevel debug: This ensures that more verbose logging is enabled, capturing detailed activity, requests, and rates inside K9s to assist with thorough diagnostics.
• --cluster cluster_name: Specifies the exact cluster being managed and monitored.

Example Output: The result will be a detailed pod-centric view within the K9s interface, accompanied by comprehensive logging output, which is particularly useful for developers or operators who need to understand the nuanced behavior of pods or diagnose complex issues within their applications.

Conclusion:

K9s is a robust tool that enhances Kubernetes cluster management efficiency by offering various modes and views to suit different administrative and development needs. From context management to namespace-focused oversight and debugging capabilities, K9s can cater to diverse workflows and technical scenarios, making it an indispensable tool for cloud-native operations.