As the question shows, I have very low knowledge about kubernetes. Following a tutorial, I made a Kubernetes cluster to run a web app on a local server using Minikube. I have applied the kubernetes components and they are running but the Web-Server does not respond to HTTP requests. My problem is that all the system that I have created is like a black box for me and I have literally no idea how to open it and see where the problem is. Can you explain how I can debug such implementaions in a wise way. Thanks.
use a tool like https://github.com/kubernetes/kubernetes-dashboard
You can install kubectl and kubernetes-dashboard in a k8s cluster (https://kubernetes.io/docs/tasks/tools/install-kubectl/), and then use the kubectl command to query information about a pod or container, or use the kubernetes-dashboard web UI to query information about the cluster.
For more information, please refer to https://kubernetes.io/
kubectl get pods
will show you all your pods and their status. A quick check to make sure that all is at least running.
If there are pods that are unhealthy, then
kubectl describe pod <pod name>
will give some more information.. eg image not found etc
kubectl log <pod name> --all
is often the next step , use -f to follow the logs as you exercise your api.
It is possible to link up images running in a pod with most ide debuggers, but instructions will differ depending on language and ide used...
Related
I have deployed a k8s service, however its not showing any pods. This is what I see
kubectl get deployments
It should create on the default namespace
kubectl get nodes (this shows me nothing)
How do I troubleshoot a failed deployment. The test-control-plane is the one deployed by kind this is the k8s one I'm using.
kubectl get nodes
If above command is not showing anything which mean there is no Nodes in your cluster so where your workload will run ?
You need to have at least one worker node in K8s cluster so deployment can schedule the POD on it and run the application.
You can check worker node using same command
kubectl get nodes
You can debug more and check the reason of issue further using
kubectl describe deployment <name of your deployment>
To find out what really went wrong, first follow the steps described in Harsh Manvar in his answer. Perhaps obtaining that information can help you find the problem. If not, check the logs of your deployment. Try to list your pods and see which ones did not boot properly, then check their logs.
You can also use the kubectl describe on pods to see in more detail what went wrong. Since you are using kind, I include a list of known errors for you.
You can also see this visual guide on troubleshooting Kubernetes deployments and 5 Tips for Troubleshooting Kubernetes Deployments.
Am actually new to kubernetes, but as now am good with the terms such as deployment, pods etc.
Well i was trying an example of HPA (Horizontal pod autoscaler), and as prerequisite metrics-servers is already integrated, but after all those things am not able to see HPA working as expected
enter image description here
When execute below cmd-
Kubectl get hpa
Unknown in the target, although i have tried all my luck referring online forum but didn't got any break through
Any help would be really appreciated
Thank you
I was getting same issue, fixed after adding cpu requests in my pod defination. Below points can be the reason in most of the cases
Metric server is not installed in your kubernates cluster, you can check with command
(kubectl get deploy,svc -n kube-system | egrep metrics-server)
Check if you have provided resources for deployment/sts/pod definations
If I look at my logs in GCP logs, I see for instance that I got a request that gave 500
log_message: "Method: some_cloud_goo.Endpoint failed: INTERNAL_SERVER_ERROR"
I would like to quickly go to that pod and do a kubectl logs on it. But I did not find a way to do this.
I am fairly new to k8s and GKE, any way to traceback the pod that handled that request?
You could run command "kubectl get pods " on each node to check the status of all pods and could figure out accordingly by running for detail description of an error " kubectl describe pod pod-name"
As mentioned in #Neelam answer, you can can get the pod names with the command kubectl get pods -A and log into all your pods to find the error.
Or, alternatively, you could deploy a custom monitoring system like Elastic GKE Logging available in GCP github Click-to-deploy.
See here to install from MarketPlace with few clicks.
It is a free alternative to have a complete monitoring system and you can filter your logs in Kibana dashboard after deployed.
I am having a IBM cloud powered kubernetes cluster. That cluster currently have only 1 node.
I verified running the command kubectl get nodes.
There are few servers which are running in that node. I want to restart one of those server.
How can I get into the node and perform a restart for the required server?
I tried ssh, but this link says it cannot be done directly.
Seems like your main questions are:
"how to restart a pod", "how to ssh to a entity in which my service is running" and "how to see if I deleted a Pod".
First of all, most of this questions are already answered on StackOverflow. Second of all you need to get familiar with Kubernetes basic terminology and how things work in here. You can do that in any Kubernetes introduction or in documentation.
Answering the questions:
1) About restarting you can find information here. Or if you have running deployment, deleting a pod will result in pod recreation.
2) you can use kubectl execas described here:
kubectl exec -ti pod_name sh(or bash)
3) to see your pods, run kubectl get pods after you run kubectl delete pod name -n namespace you can run kubectl get pods -w to see changing status of deleted pod and new one being spawned. Or you will notice that there is a new pod running but with different NAME.
I have installed a K8S cluster on laptop using Kubeadm and VirtualBox. It seems a bit odd that the cluster has to be up and running to see the documentation as shown below.
praveensripati#praveen-ubuntu:~$ kubectl explain pods
Unable to connect to the server: dial tcp 192.168.0.31:6443: connect: no route to host
Any workaround for this?
See "kubectl explain — #HeptioProTip"
Behind the scenes, kubectl just made an API request to my Kubernetes cluster, grabbed the current Swagger documentation of the API version running in the cluster, and output the documentation and object types.
Try kubectl help as an offline alternative, but that won't be as complete (limite to kubectl itself).
So the rather sobering news is that AFAIK there's not out-of-the box way how to do it, though you could totally write a kubectl plugin (it has become rather trivial now in 1.12). But for now, the best I can offer is the following:
# figure out which endpoint kubectl uses to retrieve docs:
$ kubectl -v9 explain pods
# from above I learn that in my case it's apparently
# https://192.168.64.11:8443/openapi/v2 so let's curl that:
$ curl -k https://192.168.64.11:8443/openapi/v2 > resources-docs.json
From here you can, for example, use jq to query for the descriptions. It's not as nice as a proper explain, but kinda is a good enough workaround until someone writes an docs offline query kubectl plugin.
The 'explain' documentation lives in the kube-apiserver and its resource definitions. Hence the need to connect to it through kubectl explain to get any docs. This is different from the standard very basic cli help from kubectl where it's in the kubectl Golang code.
So no workaround really other than setting up a dummy Kubernetes cluster and have kubectl point to it. Please note that CRDs help might not be available since they live in the deployed CRDs themselves.