部署、扩展、更新、删除都要有顺序 2. The . This page shows how to delete Pods which are part of a stateful set, and explains the considerations to keep in mind when doing so. StatefulSet is the workload API object used to manage stateful applications. 9. . As with StatefulSet creation, the StatefulSet controller created each Pod sequentially with respect to its ordinal index, and it waited for each Pod's predecessor to be Running and Ready before launching the subsequent Pod. The execution of a Pod depends on other ordinal index. To revert the deployment to the previous working version, use the rollout undo command: kubectl rollout undo statefulset/dbc1 -n mysql1 The output is similar to the following:Kubernetes Deployment vs StatefulSet: Which is Right for You? Kubernetes for Developers: Overview, Insights, and Tips. Deploy and Manages the stateless application. 2. 1 Answer. These pods are created from the same specification, but they are not interchangeable: each one has a persistent identifier maintained across any. One pod should be able to reach other pods with well-defined names. I was playing with k8s deployment - rolling update and it works really well. Of course, the scaling depends on the app you are deploying. 10 sidecar injection. 1 Like. The hostnames take the form of <statefulset name>-<ordinal index>. There were no major changes to the API Object, other than the community selected name, but we added the semantics of “at most one pod per index” for deployment of the Pods in. The StatefulSet controller provides each Pod with a unique hostname based on its ordinal index. StatefulSet is the workload API object used to manage stateful applications. When you revert the deployment of an upgraded binary version, the rollout process is reversed and a new set of Pods is deployed with the previous image version. Nevertheless, Kubernetes Operator does the same job. DaemonSets. (PV) controllers and architectures like DaemonSet and StatefulSet which remain in operation even when Kubernetes scales and provisions cluster resources and ensures. The manifest files do not have the namespace added to them. Even when there is a new rolling update, the statefulset still in the same state CrashLoopBackOff from the old rolling update. Meaning you can create a Replica set containing only one Pod specifying to run only one instance of that Pod. Nota: Los StatefulSets son estables (GA) en la versión 1. Deployment vs. In the previous blog we created a stateless application, deployed with K8s resource Deployment, which allows one to replicate the application, but where data is lost when Pods are restarted, meaning there were no data consistency. Like a Deployment, a StatefulSet manages Pods that are based on an identical container. field to . k8s. These are applications that can easily scale. How to Use kubectl rollout restart. Additionally, StatefulSet maintains a sticky. The following provides an example of deploying a single Kubernetes MySQL instance using Trident. You can define deployments to. StatefulSets are used when state has to be persisted. A StatefulSet is a Kubernetes API object for managing stateful application workloads. StatefulSetではこれを防ぐために、kubeletが落ちても新たにPodの自動起動をしない。 言い換えると、Podを手動で削除しない限り、新たなPodは起動されない。 Podを自動で起動してほしい場合. Your Deployment yaml should be like below: containers: - name: nginx image: nginx volumeMounts: - mountPath: /etc/nginx name: nginx-conf volumes: - name: nginx-conf configMap: name: nginx-conf items: - key:. For a typical Kubernetes Pod, it will be managed by a higher-level controller like a Deployment. Unlike a. Deploymentなど、StatefulSet以外のリソースを使う必要がある。Author: Matthew Cary (Google) Kubernetes v1. For example, if you create a StatefulSet named “my-statefulset” with three replicas, the pod names would be “my-statefulset-0”, “my-statefulset-1”, and “my-statefulset-2”. In a stateful containerized application, data must be persistent, retained and easy to access outside the application. io. It is an ordered and graceful deployment. Rolling Update Strategy. To decide how to handle updates, StatefulSets use an update strategy defined in spec: updateStrategy. This registry. One of the most powerful tools Kubernetes provides in this area are the securityContext settings that every Pod and Container manifest can leverage. The StatefulSet name is derived from the Elasticsearch resource name and the NodeSet name. Pods (and, by extension, containers) are, nevertheless, short-lived entities. Deploying a. g. 16. apps/web scaled deepak. But it differs from a Deployment in that it is more suited for stateful apps. Caching Systems: StatefulSets can be used to deploy caching systems in Kubernetes, as they provide stable network identities, persistent storage, and predictable deployment and scaling. Statefulset es un recurso que controla y gestiona en kubernetes uno o más Pods, pero entonces por qué no usar un Deployment te estarás preguntando?, entonces antes de continuar es mejor. If this is a serious project you should definitely change it to a statefulset. StatefulSet - manages/maintains stable hostname, network ID and persistent storage. 1. Choosing the right workload deployment type doesn't affect performance, but the StatefulSet does provide identity stickiness requirements. The naming convention, network names, and storage persist as replicas are rescheduled with a StatefulSet. Step-1: Defining a Secret. kubectl rollout undo deployment/<deployment name> – Rollback a. io. statefulsets do ordinal scheduling; first pod 0, then pod 1, etc. spec: serviceAccountName: build-robot. Skipping a pod deployment in statefulset. Deployment and StatefulSet are two of the most popular and powerful features of Kubernetes. Kubernetes StatefulSet is the workload API object used to manage stateful applications. This is a simple YAML notation that maps two values certificates. spec): missing required field "serviceName" in io. That's it! With these two commands, you have launched all the components required to run an highly available and redundant MongoDB replica set. Pods follow a defined lifecycle, starting in the Pending phase, moving through Running if at least one of its primary containers starts OK, and then through either the Succeeded or Failed phases depending on whether any container in the Pod terminated in failure. Deployment; ReplicaSet; StatefulSet; DaemonSet; etc; From the Google Search, I found out that there are K8s Operators such. It can manage the scaling and deployment of a collection of. Note: Pods can only reference imagePullSecrets in their own namespace, so this. updateStrategy is left unspecified. It is resilient against node failures and ensures appropriate data archiving. Delete and Recreate. Warning FailedScheduling default-scheduler 0/4 nodes are available: 4 node(s) didn't find available persistent volumes to bind. The output of the describe command in this example is the following: Name: nginx-app1. yml. As this API is embedded in Pod's spec, you can use this feature in all the high-level workload APIs, such as Deployment, DaemonSet, StatefulSet, etc. StatefulSets are particularly useful when you have stateful applications, such as databases, that require stable network identities and persistent storage. The termination of Pods is performed in reverse {N-1. Use a text editor to create a YAML file: nano StatefulSet. yaml with the following: What will happen here is that on 6 nodes of the cluster we will run a Redis. Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. Not all stateful applications scale nicely. Logs stored persistently in storage, don't represent the state of the application. This topic was automatically closed 28 days after the. So yes, StatefulSet helps preserve the order and name of the pod, but what is it that it does extra (or different) that is advantageous over a regular Deployment with respect to volumes. StatefulSets. This is known as Quality of Service (QoS) class. Statefulset is generally used with a distributed applications that require each node to have a persistent state and the ability to configure an arbitrary number of nodes. Additionally, we are creating a Persistent Volume using the volumeClaimTemplate and using it in the StatefulSet to store the PostgreSQL data. A diferencia. This page shows how to run a replicated stateful application using a StatefulSet. There was…Introduction. For example, if you have a cluster of dual-core machines, a Pod with a request of. StatefulSetCondition] You should delete everything from the status field. We are creating a StatefulSet called postgresql-db with two pods (replicas: 2). In K8s, StatefulSets are a higher-level abstraction over pods that provide guarantees about the ordering and uniqueness of pods. pod-0 may need to synchronize all of its data with an external database vs. A HorizontalPodAutoscaler (HPA for short) automatically updates a workload resource (such as a Deployment or StatefulSet), with the aim of automatically scaling the workload to match demand. This page provides an overview of init containers: specialized containers that run before app containers in a Pod. PersistentVolumes and StatefulSets are the main approaches for running stateful applications in Kubernetes. labelSelector is used to find matching Pods. Then we run the command for the deployment template : kubectl apply -f demo-deployment. Deployment vs StatefulSet. What it boils down to is that Deployment will create Pods with spec taken from the template. Their purpose is to keep a set of identical pods running and upgrade them in a controlled way. First, do a git pull to ensure you’re working on the latest revision: $ git pull origin setup-semaphore. Pods created by a StatefulSet have predictable names (and hostnames), unlike those created by a ReplicaSet . A StatefulSet is a workload API object for managing stateful applications. A stateful application requires pods with a unique identity (for example, hostname). Read more about StatefulSet here. At this point, the Green Pods retire, and Blue becomes the new Green. StatefulSet. Also, you will not have to create a PVCs in advance, and you will be able to scale it easily. As developers, we learned a lot building these Operators. Kubernetes is a powerful container orchestration tool that provides a variety of resources for managing containerized applications. Hi keycloak community, the keycloak operator currently creates the workloads as deployment which means that the pods are replaced by a new ones when they are restarted. Helm is more complex to manage than Terraform and becomes a considerable responsibility in the K8s setup. E. Create a file called redis-sts. Comme un Déploiement, un StatefulSet gère des Pods qui sont basés sur une même spécification de conteneur. In this case, you can create “headless” services by specifying. See Writing a Deployment Spec for more details. kubectl basics. 15 PDBs support custom controllers where the scale subresource is enabled. To check your version of Kubernetes, run kubectl version. It automates the deployment, provisioning, management, and orchestration of Elasticsearch on Kubernetes. Deploy Istio and validate its installation. In Kubernetes, a HorizontalPodAutoscaler automatically updates a workload resource (such as a Deployment or StatefulSet), with the aim of automatically scaling the workload to match demand. When the pod fails and stops logging, the kubectl logs -f mypod will terminate and then the shell will immediately execute kubectl describe pod mypod, (hopefully) letting you catch the state of the failing pod before it is recreated. Several other StatefulSet features also apply to this example: StatefulSet: StatefulSet is similar to deployments but with advantages such as persistent storage, unique network identifier, and graceful deployment and scaling. Kubernetes Storage allows containerized applications to access storage resources seamlessly, without being aware of the containers consuming the data. 1. Deployment Strategy: There are two strategies available in the Kubernetes Deployment. While StatefulSet is used for stateful applications like databases, Deployment component is used to deploy stateless applications. yml Statefulset . How to run stateful applications in Kubernetes. A DaemonSet is a unique kind of resource that K8s assigns to a pod for each Kubernetes node in the cluster. StatefulSet. StatefulSets, DaemonSets, and Deployments are different ways to deploy pods in Kubernetes. Editor’s note: this post is part of a series of in-depth articles on what's new in Kubernetes 1. mourya ~ % kubectl get statefulset NAME READY AGE web 0/0 33s deepak. Pod Management. It also guarantees the uniqueness and ordering of the pods. I'm using Logstash on Kubernetes and use the official Helm chart at this link. Create namespace, storageclass, Google compute Disk and persistentvolumes. StatefulSet pods have a unique identity that is comprised of an ordinal, a stable network identity, and stable storage. It is responsible for the deploying, scaling of a set of Pods, and guarantees the ordering and uniqueness of these Pods. StatefulSet. So much useful for Secrets authoring. Updates are versioned and you can revert to any previously known state of a Deployment. Making an app stateless make it much easier to run as a distributed system e. Each new pod in statefulset then have a new PV attached to them to. Learn how to run stateful applications on Kubernetes, understand how pods work in a StatefulSet, and see how to create a StatefulSet. Deployment controllers are suitable for managing stateless applications. It is rather unlikely that you will ever need to create Pods directly for a production use-case. gcr. The possible QoS classes are Guaranteed, Burstable, and. StatefulSet(stable-GA in k8s v1. Deployments and ReplicationControllers are meant for stateless usage and are rather lightweight. Finally, we will visualize and monitor all our data in. Helm Cons. This tutorial provides an introduction to managing applications with StatefulSets . They are listed below. This comes at a cost of slow scale ups and scale downs for. The Replica set can contain one or more pods and each pod can have one or more instances. ValidationError(StatefulSet. kubernetes. Using volumeClaimTemplates, each replica will get a unique PersistentVolumeClaim with statefulset whereas all replicas would share the PersistentVolumeClaim with a deployment. On the 3rd of April 2023, the old registry k8s. Kubernetes Deployment vs StatefulSet: Which is Right for You?A different kinds of replicas in the Deployment's Status can be described as follows:. The most basic difference is that you would get ability to persist pod level state with statefulsets. 23 introduced a new, alpha-level policy for StatefulSets that controls the lifetime of PersistentVolumeClaims (PVCs) generated from the StatefulSet spec template for cases when they should be deleted automatically when the StatefulSet is deleted or pods in the StatefulSet are scaled. But there are several online resources that gives you the differences between using a deployment vs statefulset for databases. Update our deployment process to deploy on both clusters, and redeploy all our applications deployed in the first deployment. These priorities does not only happens when a Node becomes unreachable, but at all times, e. podManagementPolicy. StatefulSet Deployments provide: Stable, unique network identifiers: Each pod in a StatefulSet is given a hostname that is based on the application name and increment. Expose MySQL to other pods in the cluster at a known DNS. イメージ的にはPodTemplateを持つDeploymentにPVCも追加した感. DeploymentはRollingUpdateとParallelの2つのストラテジーがあります。You can also update the object's resource requests and limits, labels, and annotations. In the same blog we used PersistentVolumeClaim for dynamic provisioning of PersistentVolume, but we used. With this alpha feature, Kubernetes allows you to restrict volume access to a single pod. Minikube is a tool used to run a single-node Kubernetes cluster locally. apiVersion: apps/v1 kind: StatefulSet metadata: name: web # this will be used as prefix in pod name spec: serviceName: "nginx" replicas: 2 # specify number of pods that should be running selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: k8s. kubectl create namespace database. This is great for stateless apps that we want online, ASAP. StatefulSet est l'objet de l'API de charge de travail utilisé pour gérer des applications avec état (stateful). In your case each deployment is having same PersistentVolumeClaim (that is ReadWriteOnly and can't be mounted on second request), while with volumeClaimTemplates you get different one provisioned per. statefulsets do ordinal scheduling; first pod 0, then pod 1, etc. A pod is the smallest deployable unit in Kubernetes which has a collection of containers. if the node becomes unreachable (e. apps/mongo created Click Check my progress to verify the objective. This controller provides stateful storage for persistent applications. In contrast to that, the Pods deployed by StatefulSet component are NOT identical and deployment is more complex. Community. But many times, due to some requirements, users make sure that the pods are deployed in order with persistent storage volume and. Like a Deployment, a StatefulSet manages Pods based on an identical container specification. Step-7: Checking the environment variable. Run a Stateless Application Using a Deployment; Run a Single-Instance Stateful Application; Run a Replicated Stateful Application; Scale a StatefulSet; Delete a. For example, you define how many replicas ( pods) of your app you want to run in the. A Replicaset is a K8s object, a set of Pod templates that describe a set of Pod replicas. StatefulSet is the workload API object used to manage stateful applications. Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. Kubernetes deployments vs. Deployment vs StatefulSet component. This page shows you how to run a single-instance stateful application in Kubernetes using a PersistentVolume and a Deployment. This document describes the concept of a StorageClass in Kubernetes. using ClusterIP services). FROM K8s Docs -> Sometimes you don’t need or want load-balancing and a single service IP. 23 version is introducing some new and updated functionality, such as Pod Security Admission, Dual-stack IPv4/IPv6 Networking, Kubelet Container Runtime Interface, the general availability of Generic Inline Volume, and much more. 15）不支持这一属性，只有StatefulSet才有，因此不得不使用后者。. StatefulSet and deployment controllers. It starts the pods in a specific order (ascending numerically). 2. Scaling Down. Cloud Observability recommends running the OpenTelemetry Collector with the Prometheus receiver to ingest infrastructure metrics. Storage classes can define properties of storage systems. StatefulSet vs. 2. I need a StatefulSet instead. pod-1 can only read a subset of the data and write to a. This blog describes the two features namely minReadySeconds for StatefulSets and maxSurge for DaemonSets that SIG Apps is happy to graduate to stable in Kubernetes 1. Issue is only with statefulset. When it comes to Kubernetes, you can scale: 1. As with all other Kubernetes API objects, a ReplicaSet needs the apiVersion, kind, and metadata fields. service没有ClusterIP，是headlessservice，所以无法负载均衡，返回的都是pod名，所以pod名字都. But even when i got reclaimPolicy:. As a pod can have one or more containers. One pod should be able to reach other pods with well-defined names. StatefulSets. kubectl basics. Kubernetes (K8s) is one of the popular open-source container orchestration systems for automating deployment, scaling, and management of containerized applications. Furthermore assigning more CPU requests to a pod does not automatically mean that the container/application will. io/ssd created Deploy etcd cluster. While Kubernetes is built to support clusters with up to 5,000 nodes orchestrating a maximum of 300,000 containers, Nomad can scale clusters exceeding 10,000 nodes in production, and surpassed the benchmark for the two million container challenge. Related Resources. But however, before statefulsets were introduced into k8s many of our database applications were deployed using PVC, it also has lot of overhead. yaml file, you will find a snippet around how we are deploying a stateful application. Create a MySQL Deployment. But unlike a regular deployment, it allows you to specify the order and dependencies of the deployment to. Kubernetes or K8s is an open-source orchestration system for containerized applications that helps in automating software deployment, management and scaling. So by passing this flag to kubectl delete the Pods that are managed by. The metadata in an annotation can be small or large, structured or unstructured, and can. En esta entrada vamos a tratar sobre aplicaciones Stateful en Kubernetes – Statefulset, el cual es un tipo de recurso que nos ofrece Kubernetes. Deployment. Pods created as part of a StatefulSet are given persistent. 2) you configure your Deployment component to use that secret using a specific imagePullSecrets attribute. The StatefulSet controller provides each Pod with a unique hostname based on its ordinal index. In robotics and automation, a control loop is a non-terminating loop that regulates the state of a system. 1 Answer. When a StatefulSet's . Replicas in a StatefulSet follow a graceful, sequential approach to deployment, scale, upgrade, and termination. This ensures it’ll be postgres-2 that’s destroyed first. I'm trying to define a shared persistent volume in k8s between two different deployments, and I've encountered some issues: I have 2 pods for each deployment and between the deployments I'm trying to configure a shared volume - that mean that if I create a txt file in deplyment1/pod1 and I take a look in deplyment1/pod2 - I can't see the file. Comme un Déploiement, un StatefulSet gère des Pods qui sont basés sur une même spécification de conteneur. Deleting and/or scaling a StatefulSet down will not delete the volumes associated with the. 1. Example-2: Define runAsUser for container. Using volumeClaimTemplates, each replica will get a unique PersistentVolumeClaim with statefulset whereas all replicas would share the PersistentVolumeClaim with a deployment. Here is what the above statefulset does: Set 3 replicas. First, we will create a. apps. DaemonSet. Do the traffic switch. Therefore the StatefulSet controller creates three Pods with their hostnames set to zookeeper-0, zookeeper-1, and zookeeper-3. A StatefulSet is a controller for stateful applications, such as databases, and manages the deployment and scaling of pods. StatefulSet. k8s. It demonstrates how to create, delete, scale, and update. One of the more powerful features of a StatefulSet is the use of persistent. Something like: apiVersion: extensions/v1beta1 kind: Deployment metadata: name: my-deployment spec: template: # Below is the podSpec. 10 how you can do it, where. When you create a StatefulSet deployment (but this is true also for Deployment), let's say with 3 pods, Kubernetes register in CoreDNS three DNS names: IP-with-dashes. The problem is : a Pod will not be re-created after the Node failure (like a reboot). StatefulSets vs. If you need to scale to (very) large clusters, and handle more traffic than a "small" StatefulSet can handle, use a Daemonset. Question. Behind the scenes, the Deployment object creates ReplicaSets to run the required instances. Because the replicas field of the zk StatefulSet is set to 3, the Set's controller creates three Pods with their hostnames set to zk-0, zk-1, and zk-2. It is clearly explained in the documentation under Deleting the Statefulset: Deleting a StatefulSet through kubectl will scale it down to 0, thereby deleting all pods that are a part of it. yaml We need to create a Stateful yaml file for deploying MongoDB on Kubernetes. StatefulSets are Kubernetes objects used to consistently deploy stateful application components. For a StatefulSet with N replicas, each Pod in the StatefulSet will be assigned an integer ordinal, from 0 up through N-1, that is unique over the Set. StatefulSets. Deployment or ReplicaSet may be better suited to your stateless needs. system (system) Closed March 11, 2022, 6:44am 3. Unlike a Deployment, a StatefulSet maintains a sticky identity for each of their Pods. This controller runs Jobs -- components of a Kubernetes workload that execute specific tasks -- according to. 安定したネットワーク識別子. Ordering: Kubernetes StatefulSet ensures that each pod is created in a specific order, while Deployment does not. 9) is a Kubernetes resource used to manage stateful applications. 5, we’ve moved the feature formerly known as PetSet into beta as StatefulSet. In order not to alter or use the default one I want to create service account and mount certificate into the pods of a deployment. Kubernetes proporciona un recurso base llamado Pod (cápsula). Kubernetes StatefulSet simply explained | Deployment vs StatefulSet. PersistentVolumes. For simplicity, are we using Nginx as the pod image. StatefulSets. By baking K8s. service没有ClusterIP，是headlessservice，所以无法负载均衡，返回的都是pod名，所以pod名字都. StatefulSet is a workload API object designed to assist in managing stateful applications. g. e. イメージ的にはPodTemplateを持つDeploymentにPVCも追加した感じ。. Our Mongodb Setup will be as follows : 1x Config Server (k8s deployment type: “StatefulSet”)Stateful Applications in Kubernetes. Specifying minReadySeconds slows down a rollout of a StatefulSet, when using a RollingUpdate value in . We are now in the interesting part of this meal. It is important to remember that you cannot set requests that are larger than resources provided by your nodes. Kubernetes users don’t need to worry about how pods are scheduled—they can deploy pods sequentially, attach them to persistent storage volumes, and each pod maintains its own persistent network ID. StatefulSet ensures that, at any time, there is at most one Pod with a given identity running in a cluster. The upgrade process is as follows: Creation of the new cluster inside the same Virtual Private Cloud (VPC) Bootstrap of cluster. Deployments with three replicas all schedule simultaneously. Deployment vs Statefulset. In my understanding JGroups Cluster is designed to work with stable node identities like they are provided by statefulset. If you don’t have a Deployment or StatefulSet managing your pods, you can delete the existing pods and let Kubernetes recreate them with the same configuration. However, the order matters in a StatefulSet, and K8s will maintain that order when scaling up or down to ensure stability. StatefulSet is a Kubernetes controller used to deploy stateful apps. Get Full-Length High-Quality DevOps Tutorials for Free - Subscribe Now. StatefulSets. The solution(s) : Use a StatefulSet, ReplicaSet or DaemonSet to ensure the Pod creation after a Node failure. On an update the existing Pods will get deleted and recreated. Note: This is not a production configuration. StatefulSets maintain the state of applications beyond an individual pod lifecycle. 1 Answer. Deploying workloads as StatefulSet helps provide features like unique. if the node becomes unreachable (e. Latest Deployment Generation: kube_deployment_metadata_generation: Sequence number representing the latest generation of a Deployment. The Reclaim Policy is used to determine the actions that need to be taken by the storage backend on deletion of the PV. Also, you will not have to create a PVCs in advance, and you will be able to scale it easily. a cache or database cluster even though it may solve your specific situation as. yaml. Logs stored persistently in storage, don't represent the state of the application. network issue), for Deployment, a new Pod will be created on a different node (to follow your desired 1 replica), but for StatefulSet it will make sure to terminate the existing Pod before creating a new, so that there are never more than 1 (when you have 1 as desired number of replicas). Now, I have a task to. Scaling a StatefulSet refers to increasing or decreasing the number of replicas. Authors: Mahamed Ali (Rackspace Technology) The Kubernetes project runs a community-owned image registry called registry. 2. Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. StatefulSets handle the deployment and scaling of sets of Kubernetes pods, providing guarantees about their uniqueness and ordering. StatefulSetSpecPic from k8s. yaml kubectl apply -f mongo-statefulset. service. Deploying a MongoDB Database: Here is an example of how to deploy a MongoDB database using a StatefulSet in Kubernetes. This is important because many stateful applications have data initialization routines to perform, masters to elect, and quorum to achieve. Deployments vs Daemonsets vs Statefulsets. pods. If you look at web_stateful. A good example of an application that could use a Deployment is a web server or a microservice. Description. spec. StatefulSet and Deployment both aim to maximise availability, however StatefulSet is constrained by its inability to. php with a username/password that it. e. StatefulSetには以下のような特徴がある。. Each individual deployment is represented as a replication controller. It uses a template to describe what each Pod must contain. Pods deployed by Deployment are identical and interchangeable, created in random order with random hashes in their Pod names. moury~ % kubectl scale statefulset web --replicas=3 statefulset. If. Then, the second pod (2) does likewise. When you’re deploying an application in Kubernetes, you have a few options to choose from. Scaling down a Deployment removes arbitrary Pods, which could include the primary node in your database system. Before going for statefulset we should understand the concept of stateful and stateless applications Yes, Statefulset is the way to go if the pods need to have their identity defined in some way. Instead, it returns the IP addresses of the pods associated with it directly to the DNS system, allowing clients to connect to individual pods directly. Here is the quote from a relevant section from the docs: Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. Conclusion. To ensure high availability of the application, we need to maximize the uptime of the core PHP application, the underlying storage layer backing the file system, and the. This application is a replicated MySQL database. It demonstrates how to create, delete, scale, and update the Pods of StatefulSets.