K3s NodeOutOfDisk

What is K3s NodeOutOfDisk

Understanding K3s: A Lightweight Kubernetes Distribution

K3s is a lightweight Kubernetes distribution designed for resource-constrained environments and edge computing. It simplifies the deployment and management of Kubernetes clusters by reducing the overhead associated with traditional Kubernetes installations. K3s is particularly popular for IoT devices, ARM processors, and environments where quick setup and minimal resource usage are critical.

Identifying the NodeOutOfDisk Symptom

When a node in a K3s cluster runs out of disk space, it can lead to various operational issues. The most common symptom is the inability to schedule new pods on the affected node. Existing pods may also experience degraded performance or fail to operate correctly. The error message 'NodeOutOfDisk' is typically observed in the node's status or in the logs, indicating that the node has insufficient disk space to continue normal operations.

Exploring the NodeOutOfDisk Issue

The 'NodeOutOfDisk' issue arises when a node's available disk space falls below a critical threshold. Kubernetes nodes require sufficient disk space to store container images, logs, and other operational data. When disk space is exhausted, Kubernetes cannot allocate resources for new pods, and existing pods may be evicted or fail to start. This issue is particularly common in environments with limited storage capacity or where disk usage is not actively monitored.

Common Causes of Disk Space Exhaustion

Accumulation of container images and logs. Large volumes of data generated by applications. Insufficient initial disk allocation.

Steps to Resolve the NodeOutOfDisk Issue

To resolve the 'NodeOutOfDisk' issue, follow these steps to free up disk space or add additional storage:

Step 1: Identify Disk Usage

Use the following command to check disk usage on the affected node:

df -h

This command provides an overview of disk space usage, helping you identify which directories or files are consuming the most space.

Step 2: Clean Up Unused Docker Images

Remove unused Docker images to free up space:

docker image prune -a

This command deletes all unused images, freeing up disk space.

Step 3: Clear Unnecessary Logs

Check and clear logs that are no longer needed:

journalctl --vacuum-time=1d

This command removes logs older than one day, which can significantly reduce disk usage.

Step 4: Add Additional Storage

If disk space is still insufficient, consider adding additional storage to the node. This can be done by attaching a new disk or expanding existing storage volumes.

Further Reading and Resources

K3s Official Documentation Kubernetes Node Documentation Docker Image Pruning

By following these steps, you can effectively resolve the 'NodeOutOfDisk' issue and ensure your K3s cluster operates smoothly. Regular monitoring and maintenance of disk usage are recommended to prevent future occurrences.