In contrast to classical deployment managers like systemd or pm2Kubernetes does not provide a simple restart my application command.
Consider configuring a rolling update strategy before doing this if you are updating a production application that should have minimal downtime.
Be sure to fill in the actual name of your deployment here. Credits for the original solution idea to pstadler on GitHub. Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website.
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How to force restarting all Pods in a Kubernetes Deployment
But opting out of some of these cookies may have an effect on your browsing experience. Necessary Always Enabled. Non-necessary Non-necessary.This is part 2 of our journey to implementing a zero downtime update of our Kubernetes cluster. In part 1 of the serieswe laid out the problem and the challenges of naively draining our nodes in the cluster.
In this post, we will cover how to tackle one of those problems: gracefully shutting down the Pods. By default, kubectl drain will evict pods in a way to honor the pod lifecycle. What this means in practice is that it will respect the following flow:. Based on this flow, you can leverage preStop hooks and signal handling in your application pods to gracefully shutdown your application so that it can "clean up" before it is ultimately terminated.Load Testing Kubernetes: How to Optimize Your Cluster Resource Allocation in Production [I]
For example, if you have a worker process streaming tasks from a queue, you can have your application trap the TERM signal to indicate that the application should stop accepting new work, and stop running after all current work has finished. Or, if you are running an application which can't be modified to trap the TERM signal a third party app for examplethen you can use the preStop hook to implement the custom API that the service provides for graceful shut down of the application.
In our example, Nginx does not gracefully handle the TERM signal by default, causing existing requests being serviced to fail. Therefore, we will instead rely on a preStop hook to gracefully stop Nginx.
We will modify our resource to add a lifecycle clause to the container spec. The lifecycle clause looks like this:. Note that since the command will gracefully stop the Nginx process and the pod, the TERM signal essentially becomes a noop. This should be nested under the Nginx container spec.
When we include this, the full config for the Deployment looks as follows:. The graceful shutdown of the Pod ensures Nginx is stopped in a way to service the existing traffic before shutting down. However, you may observe that despite best intentions, the Nginx container continues to receive traffic after shutting down, causing downtime in your service. For the sake of this example, we will assume that the node had received traffic from a client.
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This will spawn a worker thread in the application to service the request. We will indicate this thread with the circle on the pod container. Suppose that at this point, a cluster operator decides to perform maintenance on Node 1. As part of this, the operator runs the command kubectl drain node-1causing the kubelet process on the node to execute the preStop hook, starting a graceful shutdown of the Nginx process:.
Because nginx is still servicing the original request, it does not immediately terminate. However, when nginx starts a graceful shutdown, it errors and rejects additional traffic that comes to it. At this point, suppose a new server request comes into our service. Since the pod is still registered with the service, the pod can still receive the traffic. If it does, this will return an error because the nginx server is shutting down:.
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To complete the sequence, eventually nginx will finish processing the original request, which will terminate the pod and the node will finish draining:. In this example, when the application pod receives the traffic after the shutdown sequence is initiate, the first client will receive a response from the server.
I have a pod testxn5jn with 2 containers.
I'd like to restart one of them called container-test. Is it possible to restart a single container within a pod and how? If not, how do I restart the pod? Not through kubectlalthough depending on the setup of your cluster you can "cheat" and docker kill the-sha-goes-herewhich will cause kubelet to restart the "failed" container assuming, of course, the restart policy for the Pod says that is what it should do.
That depends on how the Pod was created, but based on the Pod name you provided, it appears to be under the oversight of a ReplicaSet, so you can just kubectl delete pod testxn5jn and kubernetes will create a new one in its place the new Pod will have a different name, so do not expect kubectl get pods to return testxn5jn ever again.
There are cases when you want to restart a specific container instead of deleting the pod and letting Kubernetes recreate it. Both pod and container are ephemeral, try to use the following command to stop the specific container and the k8s cluster will restart a new container. All other processes will be children of process 1, and will be terminated after process 1 exits. See the kill manpage for other signals you can send.
The whole reason for having kubernetes is so it manages the containers for you so you don't have to care so much about the lifecyle of the containers in the pod. Since you have a deployment setup that uses replica set. You can delete the pod using kubectl delete pod testxn5jn and kubernetes will manage the creation of a new pod with the 2 containers without any downtime.
Trying to manually restart single containers in pods negates the whole benefits of kubernetes. All the above answers have mentioned deleting the pod We use a pretty convenient command line to force re-deployment of fresh images on integration pod.
We noticed that our alpine containers all run their "sustaining" command on PID 5. The container restarts automatically. In my case when I changed the application config, I had to reboot the container which was used in a sidecar pattern, I would kill the PID for the spring boot application which is owned by the docker user.
Learn more. Restart container within pod Ask Question. Asked 2 years, 7 months ago. Active 6 months ago. Viewed k times.
The pod was created using a deployment. Active Oldest Votes. Is it possible to restart a single container Not through kubectlalthough depending on the setup of your cluster you can "cheat" and docker kill the-sha-goes-herewhich will cause kubelet to restart the "failed" container assuming, of course, the restart policy for the Pod says that is what it should do how do I restart the pod That depends on how the Pod was created, but based on the Pod name you provided, it appears to be under the oversight of a ReplicaSet, so you can just kubectl delete pod testxn5jn and kubernetes will create a new one in its place the new Pod will have a different name, so do not expect kubectl get pods to return testxn5jn ever again.
If I can do this: docker kill the-sha-goes-herethen why not do docker container restart the-sha-goes-here instead?Edit This Page. Set which Kubernetes cluster kubectl communicates with and modifies configuration information. See Authenticating Across Clusters with kubeconfig documentation for detailed config file information. It creates and updates resources in a cluster through running kubectl apply. This is the recommended way of managing Kubernetes applications on production.
See Kubectl Book. The file extension. List all supported resource types along with their shortnames, API groupwhether they are namespacedand Kind :. To output details to your terminal window in a specific format, add the -o or --output flag to a supported kubectl command. Kubectl verbosity is controlled with the -v or --v flags followed by an integer representing the log level.
General Kubernetes logging conventions and the associated log levels are described here.
Gracefully Shutting Down Pods in a Kubernetes Cluster
Also kubectl Usage Conventions to understand how to use it in reusable scripts. See more community kubectl cheatsheets. Thanks for the feedback.
If you have a specific, answerable question about how to use Kubernetes, ask it on Stack Overflow. Open an issue in the GitHub repo if you want to report a problem or suggest an improvement. This page is an overview of the kubectl command. Will cause a service outage. Create an Issue Edit This Page. Output in the plain-text format with any additional information, and for pods, the node name is included. Useful steady state information about the service and important log messages that may correlate to significant changes in the system.
This is the recommended default log level for most systems.Edit This Page. This page shows how to delete Pods which are part of a stateful set Manages the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods. The StatefulSet controller is responsible for creating, scaling and deleting members of the StatefulSet.
It tries to ensure that the specified number of Pods from ordinal 0 through N-1 are alive and ready. StatefulSet ensures that, at any time, there is at most one Pod with a given identity running in a cluster. This is referred to as at most one semantics provided by a StatefulSet.
Manual force deletion should be undertaken with caution, as it has the potential to violate the at most one semantics inherent to StatefulSet. StatefulSets may be used to run distributed and clustered applications which have a need for a stable network identity and stable storage.
These applications often have configuration which relies on an ensemble of a fixed number of members with fixed identities. Having multiple members with the same identity can be disastrous and may lead to data loss e. For the above to lead to graceful termination, the Pod must not specify a pod. TerminationGracePeriodSeconds of 0. The practice of setting a pod. Graceful deletion is safe and will ensure that the Pod shuts down gracefully before the kubelet deletes the name from the apiserver.
Kubernetes versions 1. Pods may also enter these states when the user attempts graceful deletion of a Pod on an unreachable Node. The only ways in which a Pod in such a state can be removed from the apiserver are as follows:.
The recommended best practice is to use the first or second approach. If a Node is confirmed to be dead e. If the Node is suffering from a network partition, then try to resolve this or wait for it to resolve. When the partition heals, the kubelet will complete the deletion of the Pod and free up its name in the apiserver.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Already on GitHub? Sign in to your account. It we be helpful to have an option to clear the counter and the history of the pod without deleting it.
We use liveness and readiness as well probe in all our apps self healing. Liveness probe does restart the pod when failed and increment the restart counter and adjust the date. The problem is when an app can crash or does not answer to liveness probe at time and be killed the restart counter is incremented.
This is not so easy to monitor the frequency of restarts or perhaps for cosmetic reason I want the restart count of all my pod to be 0.
The only way for the moment is to delete the pod, then a new one is schedule and my output looks pretty again. I'm monitoring the same things and running into the same issue as ut0mt8. For normal pods quickest way hack is to delete the pod.
But this doesn't work for the 'kube-scheduler', as the same pod name is used. Now, the question is on how to do it, when I do etcdctl ls on my cluster etcd v3it only shows me the flannel keys.
By default etcdctl is acting in v2 api, so when not specifying the protocol you only show flannel key cause flannel continue to speak in v2. To view v3 entries you can try something like :. I'd also love this feature. It may not be the intention of the metric, but it comes accross a lot like port error counters on switches do.
A common ops pattern in that is to see a problem, diagnose, fix it, then clear the error counters so you can see if something is wrong next time you look.
Issues go stale after 90d of inactivity. Stale issues rot after an additional 30d of inactivity and eventually close. Should we implement this with a new kubectl command? Edit: we could also use kubectl patch validation function is here.
Same here, after a long weekend with major outages, I'm spending the morning deleting pods in order to clear out our alerts from our monitoring system that are based on the restart counter sysdig.
This feature would save our devops team and on-call personnel time and effortsand keep our system more stable not having to delete pods.
Would love this! Would a PR be accepted based on Nodraak 's suggestion? Would love to see this too. Are there any arguments against realizing this - apart from the effort? I suspect, as pods are by definition mortal in Kubernetes model, this feature is unfortunately just low prio. But, yes, considering how many of us deliberately kill pods in order just to reset useful restart counter, some good soul might eventually step up and implement this much wanted feature.
In the meantime we can continue wasting electricity and polute Mother Earth with needless CPU cycles, just to get that simple but important counter back to zero. Actually, an environment issue.Edit This Page. This page shows how to configure process namespace sharing for a pod. When process namespace sharing is enabled, processes in a container are visible to all other containers in that pod.
You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using Minikubeor you can use one of these Kubernetes playgrounds:.
Your Kubernetes server must be at or later than version v1. To check the version, enter kubectl version. Process Namespace Sharing is a beta feature that is enabled by default. Process Namespace Sharing is enabled using the shareProcessNamespace field of v1. For example:. You can signal processes in other containers.
Pods share many resources so it makes sense they would also share a process namespace. The container process no longer has PID 1. Some container images refuse to start without PID 1 for example, containers using systemd or run commands like kill -HUP 1 to signal the container process. In pods with a shared process namespace, kill -HUP 1 will signal the pod sandbox.
Processes are visible to other containers in the pod. These are protected only by regular Unix permissions. This makes debugging easier, but it also means that filesystem secrets are protected only by filesystem permissions. Thanks for the feedback. If you have a specific, answerable question about how to use Kubernetes, ask it on Stack Overflow.
Open an issue in the GitHub repo if you want to report a problem or suggest an improvement. Kubernetes v1. The version you are currently viewing is a static snapshot. For up-to-date documentation, see the latest version. Code is well tested. Enabling the feature is considered safe. Enabled by default.
Support for the overall feature will not be dropped, though details may change. When this happens, we will provide instructions for migrating to the next version. This may require deleting, editing, and re-creating API objects. The editing process may require some thought. This may require downtime for applications that rely on the feature.
Recommended for only non-business-critical uses because of potential for incompatible changes in subsequent releases. If you have multiple clusters that can be upgraded independently, you may be able to relax this restriction.
Please do try our beta features and give feedback on them! After they exit beta, it may not be practical for us to make more changes. Create an Issue Edit This Page.