When a Node in a Kubernetes cluster crashes or shuts down, it enters the ‘NotReady‘ state in which it can’t be used to run Pods and all stateful Pods running on it become unavailable.
Common reasons of the ‘NotReady‘ error include a lack of resources on the Node, connectivity issue between the Node and the Control Plane, or an error related to a kube-proxy or kubelet.
This note shows how to troubleshoot the Kubernetes Node ‘NotReady‘ state. (more…)
When you deploy an application in a Kubernetes cluster, you usually set some labels on the Pods e.g. app=my-app.
These labels can be used as a wildcard for selecting a group of Pods for deletion.
This short note shows how to perform a wildcard deletion of Pods in Kubernetes. (more…)
Kubernetes events are automatically created when resources have state changes, errors or other messages that should be broadcasted to the system.
These events (logs) are very helpful for debugging issues in a Kubernetes cluster.
In this note i will show how to get events from a specific Node in the Kubernetes cluster using the kubectl command. (more…)
A Pod is a group of one or more containers with shared storage, network and lifecycle and is the basic deployable unit in Kubernetes.
Each Pod is scheduled on the same Node, and remains there until termination or deletion.
In this note i will show how to get Pods running on a specific Node using the kubectl command. (more…)
Out of the box, there is a Namespace called ‘default‘ in a Kubernetes cluster.
By default, the kubectl command interacts with this ‘default‘ Namespace, but it can be changed to any other Namespace.
In this note i will show how to set the default Namespace in Kubernetes. (more…)
Imagine the situation, when you are starting a Deployment of some application on a Kubernetes cluster by running, for example, the kubectl create deployment command.
Then you execute the kubectl get pods command to list the Pods, but it returns “No resource found“, that means the Deployment hasn’t created any Pods.
Below i will show you how to start troubleshooting when the Deployment is not creating the Pods on a Kubernetes cluster. (more…)
Minikube is a single-node Kubernetes cluster that can be installed on macOS, Linux and Windows.
It lets you to try out Kubernetes locally on your personal computer or use it for daily development work.
In this note i will show how to install Minikube & Kubectl on Windows and deploy a first “Hello Minikube” application on a local Kubernetes cluster. (more…)
During the first attempt to start Minikube you may receive the following error: “This computer doesn’t have VT-X/AMD-v enabled“.
This error may occur even if virtualization is enabled in BIOS and you don’t have any issues with creating and running the virtual machines on your computer.
This note shows a fast workaround of the error: “This computer doesn’t have VT-X/AMD-v enabled“. (more…)
While troubleshooting Kubernetes-related issues it is useful to know how to increase the verbosity level of the main debugging tool – the kubectl command.
The verbosity of the kubectl command is controlled by the -v or --v flags followed by an integer from 0 to 9 that represents the log level.
In this note i will show how to increase the verbosity level of the kubectl command, that is extremely useful for debugging of the Kubernetes-related issues. (more…)
kubectl apply command is used to manage applications by creating and updating Kubernetes resources declared in configuration files.
In addition to possibly to manage resources through individual files, there is a way to apply all the YAML files in a folder.
In this short note i will show how to use the kubectl apply command to apply all files in a directory. (more…)