I'm trying to get all the deployments of a namespace to be restarted for implementation reasons.
I'm using "kubectl rollout -n restart deploy" and it works perfectly, but I'm not sure it that command causes downtime or if it works as the "rollout update", applying the restart one by one, keeping my services up.
Does anyone know?
In the documentation I can only find this:
Operation
Syntax
Description
rollout
kubectl rollout SUBCOMMAND [options]
Manage the rollout of a resource. Valid resource types include: deployments, daemonsets and statefulsets.
But I can't find details about the specific "rollout restart deploy".
I need to make sure it doesn't cause downtime. Right now is very hard to tell, because the restart process is very quick.
Update: I know that for one specific deployment (kubectl rollout restart deployment/name), it works as expected and doesn't cause downtime, but I need to apply it to all the namespace (without specifying the deployment) and that's the case I'm not sure about.
kubectl rollout restart deploy -n namespace1 will restart all deployments in specified namespace with zero downtime.
Restart command will work as follows:
After restart it will create new pods for a each deployments
Once new pods are up (running and ready) it will terminate old pods
Add readiness probes to your deployments to configure initial delays.
#pcsutar 's answer is almost correct. kubectl rollout restart $resourcetype $resourcename restarts your deployment, daemonset or stateful set according to the its update strategy. so if it is set to rollingUpdate it will behave exactly as the above answer:
After restart it will create new pods for a each deployments
Once new pods are up (running and ready) it will terminate old pods
Add readiness probes to your deployments to configure initial delays.
However, if the strategy for example is type: recreate all the currently running pods belonging to the deployment will be terminated before new pods will be spun up!
Related
I ran kubectl rollout restart deployment.
It created a new pod which is now stuck in Pending state because there are not enough resources to schedule it.
I can't increase the resources.
How do I delete the new pod?
please check if that pod has a Deployment controller (which should be recreating the pod), use:
kubectl get deployments
Then try to delete the Deployment with
Kubectl delete deployment DEPLOYMENT_NAME
Also, I would suggest to check resources allocation on GKE and its usage on your nodes with next command:
kubectl describe nodes | grep -A10 "Allocated resources"
And if you need more resources, try to activate GKE CA (cluster autoscaler) or in case you already have it enabled, then increase the number of nodes on Max value. You can also try to manually add a new node by manually resizing the Nodepool you are using.
I have a statefulset which constitutes of multiple pods. I have a use case where I need to invoke restart of the STS, I run this: kubectl rollout restart statefulset mysts
If I restart the statefulset at a time when one or more pods are in not-ready state, the restart action get queued up. Restart takes effect only after all the pods become ready. This could take long depending on the readiness threshold and the kind of issue the pod is facing.
Is there a way to force restart the statefulset, wherein I don't wait for pods to become ready? I don't want to terminate/delete the pods instead of restarting statefulset. A rolling restart works well for me as it helps avoid outage of the application.
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 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.
How to delete all the contents from a kubernetes node? Contents include deployments, replica sets etc. I tried to delete deplyoments seperately. But kubernetes recreates all the pods again. Is there there any ways to delete all the replica sets present in a node?
If you are testing things, the easiest way would be
kubectl delete deployment --all
Althougth if you are using minikube, the easiest would probably be delete the machine and start again with a fresh node
minikube delete
minikube start
If we are talking about a production cluster, Kubernetes has a built-in feature to drain a node of the cluster, removing all the objects from that node safely.
You can use kubectl drain to safely evict all of your pods from a node before you perform maintenance on the node. Safe evictions allow the pod’s containers to gracefully terminate and will respect the PodDisruptionBudgets you have specified.
Note: By default kubectl drain will ignore certain system pods on the node that cannot be killed; see the kubectl drain documentation for more details.
When kubectl drain returns successfully, that indicates that all of the pods (except the ones excluded as described in the previous paragraph) have been safely evicted (respecting the desired graceful termination period, and without violating any application-level disruption SLOs). It is then safe to bring down the node by powering down its physical machine or, if running on a cloud platform, deleting its virtual machine.
First, identify the name of the node you wish to drain. You can list all of the nodes in your cluster with
kubectl get nodes
Next, tell Kubernetes to drain the node:
kubectl drain <node name>
Once it returns (without giving an error), you can power down the node (or equivalently, if on a cloud platform, delete the virtual machine backing the node). drain waits for graceful termination. You should not operate on the machine until the command completes.
If you leave the node in the cluster during the maintenance operation, you need to run
kubectl uncordon <node name>
afterwards to tell Kubernetes that it can resume scheduling new pods onto the node.
Please, note that if there are any pods that are not managed by ReplicationController, ReplicaSet, DaemonSet, StatefulSet or Job, then drain will not delete any pods unless you use --force, as mentioned in the docs.
kubectl drain <node name> --force
minikube delete --all
in case you are using minikube
it will let you start a new clean cluster.
in case you run on Kubernetes :
kubectl delete pods,deployments -A --all
it will remove it from all namespaces, you can add more objects in the same command .
Kubenertes provides namespaces object for isolation and separation of concern. Therefore, It is recommended to apply all of the k8s resources objects (Deployment, ReplicaSet, Pods, Services and other) in a custom namespace.
Now If you want to remove all of the relevant and related k8s resources, you just need to delete the namespace which will remove all of these resources.
kubectl create namespace custom-namespace
kubectl create -f deployment.yaml --namespace=custom-namespace
kubectl delete namespaces custom-namespace
I have attached a link for further research.
Namespaces
I tried so many variations to delete old pods from tutorials, including everything here.
What finally worked for me was:
kubectl delete replicaset --all
Deleting them one at a time didn't seem to work; it was only with the --all flag that all pods were deleted without being recreated.