I have created a Kubernetes cluster and one of instance in the cluster is inactive
I want to review the configured Kubernetes Engine cluster of an inactive configuration by which command should I check?
Should I use this "kubectl config get-contexts"?
or
kubectl config use-context and kubectl config view?
Am beginner to cloud please anyone explains?
The kubectl config get-context will not help you debug why the instance is failing. Basically it will just show you the list ot contexts. A context is a group of cluster access parameters. Each context contains a Kubernetes cluster, a user, and a namespace. The current context is the cluster that is currently the default for kubectl . On other hand the kubectl config view will just print you kubeconfig settings.
The best way to start is the Kubernestes official documentation. It provides a good basic steps for troubleshoouting your cluster. Some of the steps can be applied to GKE as well as the Kubeadm or Minikube clusters.
If you're using GKE, then you can read the nodes logs from Stackdriver. This document is excellent start when you want to check the logs directly in the log viewer.
If one of your instaces report NotReady after listing them with kubectl get nodes I suggest to ssh to that instances and check kubernetes components (kubelet and kube-proxy). You can view the GKE nodes from the instances page.
Kube Proxy logs:
/var/log/kube-proxy.log
If you want to check the kubelet logs, they're a unit in systemd in COS that can be accessed using jorunactl.
Kubelet logs:
sudo journalctl -u kubelet
For further debugging it is worth mentioning that that GKE master is a node inside a Google managed project and it is different from your cluster project.
For the detailed master logs you will have open a google support ticket. Here is more information about how GKE cluster architecture works, in case there's something related to the api-server.
Let me know if that was helpful.
You can run below command to check status of all the nodes of a kubernetes cluster. Pleases note if you are using GKE managed service you will not be able to see status of master nodes, you will only see status of worker nodes.
kubectl get nodes -o wide
kubectl describe node nodename
You can also run below command to check status of control plane components.
kubectl get componentstatus
You can use the below command to get list of all the nodes in GKE cluster:
kubectl get nodes -o wide
Once you have the list of nodes, you can describe the node to get the events"
kubectl describe node <Node-Name>
Based on the events you can debug the node.
Related
Kubectl describe nodes ?
like wise do we have any commands like mentioned below to describe cluster information ?
kubectl describe cluster
"Kubectl describe <api-resource_type> <api_resource_name> "command is used to describe a specific resources running in your kubernetes cluster, Actually you need to verify different components separately as a developer to check your pods, nodes services and other tools that you have applied/created.
If you are the cluster administrator and you are asking about useful command to check the actual kube-system configuration it depends on your k8s cluster type for example if you are using "kubeadm" package to initialize k8s cluster on premises you can check and change the default cluster configuration using this command :
kubeadm config print init-defaults
after initializing your cluster all main server configurations files a.k.a manifests are located here /etc/kubernetes/manifests (and they are Realtime updated, change anything and the cluster will redeploy it automatically)
Useful kubectl commands :
For cluster infos (api-server domain and dns) run:
kubectl cluster-info
Either ways you can list all api-resources and check it one by one using these commands
kuectl api-resources (list all api-resources names and types)
kubectl get <api_resource_name> (specific to your cluster)
kubectl explain <api_resource_name> (explain the resource object with docs link)
For extra infos you can add specific flags, examples:
kubectl get nodes -o wide
kubectl get pods -n <specific-name-space> -o wide
kubectl describe pods <pod_name>
...
For more informations about the kubectl command line check the kubectl_cheatsheet
I did an SSH on a worker node inside the cluster and I run kubectl in there. I created a PV, a PVC and a deployment. I read on the documentation that PV is a cluster-wide object. My question is what happens in this case? In other words, Does running kubectl inside a worker node has the same effect as running it from master node?
Short answer: yes. kubectl connects to the configured API server which controls the whole cluster.
I'm using digital ocean kubernetes cluster service and have deployed 9 nodes in cluster but when i'm trying to deploy kafka zookeeper pods few pods get deployed other remain in pending state. i've tried doing
kubectl describe pods podname -n namespace
it shows
its not getting assigned to any nodes
check if your deployment/statefulset might have some node Selectors and/or node/pod affinity that might prevent it from running .
also it would be helpful to see more parts of the pod decribe since it might give more details.
there is a message on your print screen about the PersistentVolume Claims so I would also check the status of the pvc objects to check if they are bound or not.
good luck
I need to create a shell-script which examine the cluster
Status.**
I saw that the kubectl describe-nodes provides lots of data
I can output it to json and then parse it but maybe it’s just overkill.
Is there a simple way to with kubectl command to get the status of the cluster ? just if its up / down
The least expensive way to check if you can reach the API server is kubectl version. In addition kubectl cluster-info gives you some more info.
In addition to Michael's answer, that would only tell you about the API server or master and internal services like KubeDns etc, but not the nodes.
It depends on your need and definition of "status" here. You could run kubectl cluster-info followed by kubectl get nodes and check the STATUS column for all nodes using parsing tools like awk, jq or kubectl's own -o jsonpath option to verify that all nodes are ready.
The below command would display the health of scheduler, controller and etcd
kubectl get cs
Command below lists Kubernetes core components like, etcd, controller, scheduler, kube-proxy, core-dns, network plugin. All those pods should be running to be sure that Kubernetes is healthy.
kubectl get pod -n kube-system
Finally deploy one front-end and back-end Pod and verify the inter-pod communication to ensure that cluster is up and working correctly.
Below are the commands to get cluster status based on requirements:
To get information regarding where your Kubernetes master is running at, CoreDNS is running at, kubernetes-dasboard is running at, use
kubectl cluster-info
To get detailed information to further debug and diagnose cluster problem, use kubectl cluster-info dump
To get only the health status for your node use, kubectl get componentstatus or kubectl get cs
*To show detailed information about a resource use kubectl describe node <node>
Is there any command in kubectl to get the data centre details,something like
kubectl get dc
It is not very clear what is 'datacenter' in your context. If you are referring to a cluster, then kubectl cluster-info or kubectl get nodes may be what you are looking for.
If 'datacenter' is 'all clusters that this kubectl is configured to access', then maybe kubectl config get-contexts or kubectl config get-clusters is what you are looking for. (a 'context' contains everything needed to address a single cluster: the cluster name, the access credentials and the default namespace).
Not sure what you mean with "data centre details" but the biggest addressable unit in Kubernetes ATM is a cluster. All relevant info about the context you're operating in can be viewed and updated via the kubectl config command, see also the docs.