I have a deployment A where replica count is set to 1 and in Pod Disruption budget minAvailable is also set to 1. Upon describing PDB, it shows ALLOWED DISRUPTIONS as 0 but the problem is when I do kubectl drain node-1 --dry-run , the output still shows the above deployment pod evicted. Is it like dry run does not show errors ? I am using Kubernetes 1.19
Related
This question is about logging/monitoring.
I'm running a 3 node cluster on AKS, with 3 orgs, Dev, Test and Prod. The chart worked fine in Dev, but the same chart keeps getting killed by Kubernetes in Test, and it keeps getting recreated, and re-killed. Is there a way to extract details on why this is happening? All I see when I describe the pod is Reason: Killed
Please tell me more details on this or can give some suggestions. Thanks!
List Events sorted by timestamp
kubectl get events --sort-by=.metadata.creationTimestamp
There might be various reasons for it to be killed, e.g. not sufficient resources or failed liveness probe.
For SonarQube there is a liveness and readiness probe configured so it might fail. Also as described in helm's chart values:
If an ingress path other than the root (/) is defined, it should be reflected here
A trailing "/" must be included
You can also check if there are sufficient resources on node:
check what node are pods running on: kubectl get pods -test and
then run kubectl describe node <node-name> to check if there is no
disk/ memory pressure.
You can also run kubectl logs <pod-name> and kubectl describe pod <pod-name> that might give you some insight of kill reason.
Kubernetes nodes are getting unscheduled while i initiate the drain or cordon but the pods which is available on the node are not getting moved to different node immediately ?
i mean, these pods are not created by daemonset.
So, how come, Application running pod can make 100% available when a node getting faulty or with some issues ?
any inputs ?
command used :
To drain / cordon to make the node unavailable:
kubectl drain node1
kubectl cordon node1
To check the node status :
kubectl get nodes
To check the pod status before / after cordon or drain :
kubectl get pods -o wide
kubectl describe pod <pod-name>
Surprising part is , even node is unavailable, the pod status showing always running. :-)
Pods by itself doesn't migrate to another node.
You can use workload resources to create and manage multiple Pods for you. A controller for the resource handles replication and rollout and automatic healing in case of Pod failure. For example, if a Node fails, a controller notices that Pods on that Node have stopped working and creates a replacement Pod. The scheduler places the replacement Pod onto a healthy Node.
Some examples of controllers are:
deployment
daemonset
statefulsets
Check this link to more information.
I am trying to use Kubernetes Deployment , i would like to know whether this is same as kubectl apply -f deployment.yaml or does this wait for the deployments to be up and running . because when i used kubernetes deployment to create a basic pod which i know will not work, i got this error
Error: Waiting for rollout to finish: 0 of 1 updated replicas are available...
Is this just giving me the error from kubernetes or the entire terraform script fails because of this?
According to the documentation
A Deployment ensures that a specified number of pod “replicas” are running at any one time. In other words, a Deployment makes sure that a pod or homogeneous set of pods are always up and available. If there are too many pods, it will kill some. If there are too few, the Deployment will start more.
So, It will wait to ensure number of expected replicas are up
I'm looking to update manually with the command kubectl autoscale my maximum number of replicas for auto scaling.
however each time I run the command it creates a new hpa that fails to launch the pod why I don't know at all:(
Do you have an idea how i can update manually with kubectl my HPA ?
https://gist.github.com/zyriuse75/e75a75dc447eeef9e8530f974b19c28a
I think you are mixing two topics here, one is manually scale a pod (you can do it through a deployment applying kubectl scale deploy {mydeploy} --replicas={#repl}). In the other hand you have HPA (Horizontal Pod AutoScaler), in order to do this (HPA) you should have configured any app metrics provider system
e.g:
metrics server
https://github.com/kubernetes/kubernetes/tree/master/cluster/addons/metrics-server
heapster (deprecated) https://github.com/kubernetes-retired/heapster
then you can create a HPA to handle your autoscaling, you can get more info on this link https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/
Once created you can patch your HPA or deleted it and create it again
kubectl delete hpa hpa-pod -n ns-svc-cas
kubectl autoscale hpa-pod --min={#number} --max={#number} -n ns-svc-cas
easiest way
I have 3 nodes in kubernetes cluster. I create a daemonset and deployed it in all the 3 devices. This daemonset created 3 pods and they were successfully running. But for some reasons, one of the pod failed.
I need to know how can we restart this pod without affecting other pods in the daemon set, also without creating any other daemon set deployment?
Thanks
kubectl delete pod <podname> it will delete this one pod and Deployment/StatefulSet/ReplicaSet/DaemonSet will reschedule a new one in its place
There are other possibilities to acheive what you want:
Just use rollout command
kubectl rollout restart deployment mydeploy
You can set some environment variable which will force your deployment pods to restart:
kubectl set env deployment mydeploy DEPLOY_DATE="$(date)"
You can scale your deployment to zero, and then back to some positive value
kubectl scale deployment mydeploy --replicas=0
kubectl scale deployment mydeploy --replicas=1
Just for others reading this...
A better solution (IMHO) is to implement a liveness probe that will force the pod to restart the container if it fails the probe test.
This is a great feature K8s offers out of the box. This is auto healing.
Also look into the pod lifecycle docs.
kubectl -n <namespace> delete pods --field-selector=status.phase=Failed
I think the above command is quite useful when you want to restart 1 or more failed pods :D
And we don't need to care about name of the failed pod.