Deploymentなど、StatefulSet以外のリソースを使う必要がある。Node Deployment: K8s DaemonSet achieves deploying multiple instances of an application in all nodes. StatefulSetの概要. I have been trying to debug a very odd delay in my K8S deployments. This tutorial provides an introduction to managing applications with StatefulSets. MySQL settings remain on insecure defaults to. Before you begin This task assumes you have an application running on your cluster represented by a StatefulSet. Now, if I add tolerations to my container configurations in a StatefulSet if will be common for all pods of my StatefulSet and would schedule all pods on a node with matching taint. For example, you can only have one Pod named myapp-1234 within the same namespace, but you can have one Pod and one Deployment that are each named. So we will add the namespace while deploying each component. 9. The StatefulSet controller provides each Pod with a unique hostname based on its ordinal index. Kubernetes (K8s) is one of the popular open-source container orchestration systems for automating deployment, scaling, and management of containerized applications. It is the default strategy when . In one terminal, watch the StatefulSet's Pods: Yes, Statefulset is the way to go if the pods need to have their identity defined in some way. When to use a ReplicaSet. conditions[1): unknown field "lastUpdateTime" in io. spec. A stateful application requires pods with a unique identity (for example, hostname). You can use statefulsets if you want fixed pod names for your application. A Pod's contents are always co-located and co-scheduled, and run in a. However, the order matters in a StatefulSet, and K8s will maintain that order when scaling up or down to ensure stability. It manages the deployment and scaling of a set of Pods, and provides guarantee about the ordering and uniqueness of these Pods. Every Kubernetes object also has a UID that is unique across your whole cluster. kubectl delete sts --cascade=orphan <name> to delete the StatefulSet and leave its pods. 目前看来有点本末倒置，不过不. Statefulsets. The new pod will automatically spin up with correct configuration. Object Names and IDs. The answer is in your first log: The StatefulSet "cassandra" is invalid: spec: Forbidden: updates to statefulset spec for fields other than 'replicas', 'template', and 'updateStrategy'. First, we run the service template : kubectl apply -f service. Kubectl autocomplete BASH source <(kubectl completion bash) # set up autocomplete in bash into the current shell, bash-completion package should be installed. This is great for stateless apps that we want online, ASAP. your state), so it cannot act as fast as Deployment (stateless) apps can. Manages the deployment and scaling of a set of Pods, and provides. It can appear that StatefulSet is a way to solve at most one instance in a situation with a network partition, but that is mostly in case of a stateful replicated application like e. PersistentVolumes. requires writes. Kubernetes Deployment vs. Using ConfigMap in StatefulSet. A StatefulSet is a controller that helps you deploy and scale groups of Kubernetes pods. What it boils down to is that Deployment will create Pods with spec taken from the template. This chart deploys Logstash as a statefulset. pods. ; A Persistent Volume (PV) to allocate storage space for the database. This document describes the concept of a StorageClass in Kubernetes. But still for the alertmanager statefulset, only 1 pod is getting restarted. env. To check the image deployed on these Pods, use the describe pods subcommand: kubectl describe pods. Understanding ReplicaSets It will trigger them all at once. This means that a Deployment can have as many active ReplicaSets as possible, and eventually the deployment controller will scale down all old ReplicaSets and scale up the newest one. The storage for a given Pod must either be provisioned by a PersistentVolume Provisioner based on the requested storage class, or pre-provisioned by an admin. Securely running workloads in Kubernetes can be difficult. Deployment vs StatefulSet. But each resource type. Deployments vs Daemonsets vs Statefulsets. Un StatefulSet es el objeto de la API workload que se usa para gestionar aplicaciones con estado. By interpreting the documentation, it seems that it depends on the event. Run a Stateless Application Using a Deployment; Run a Single-Instance Stateful Application; Run a Replicated Stateful Application; Scale a StatefulSet; Delete a StatefulSet; Force Delete StatefulSet Pods; Horizontal Pod Autoscaling; HorizontalPodAutoscaler Walkthrough; Specifying a Disruption Budget for your Application; Accessing the. The StatefulSet manifest should feel familiar—it looks a lot like a Deployment manifest! Instead of the volume field under a Deployment’s template spec, we define a VolumeClaimTemplate under the overall StatefulSet spec to describe how the workload will consume storage. Choosing the right workload deployment type doesn't affect performance, but the StatefulSet does provide identity stickiness requirements. spec. This page shows you how to run a single-instance stateful application in Kubernetes using a PersistentVolume and a Deployment. StatefulSet. A DeploymentConfig (DC) in OpenShift is more or less equivalent to a Kubernetes Deployment, nowadays. It provides declarative updates for pods and their associated. spec. A key feature with StatefulSet is that they provide unique stable network identities for the instances. If the StatefulSet is scaled down to one replica, mysql-3 is guaranteed to exit first, followed by mysql-2. Parallel. (PV) controllers and architectures like DaemonSet and StatefulSet which remain in operation even when Kubernetes scales and provisions cluster resources and ensures. field to . The Replica set can contain one or more pods and each pod can have one or more instances. Authors: Mahamed Ali (Rackspace Technology) The Kubernetes project runs a community-owned image registry called registry. This means that the Deployment object can have as many active replica sets as possible, and eventually the deployment controller will scale down all old replica sets and scale up. apps/mongo created Click Check my progress to verify the objective. 2. Unlike a Deployment, a StatefulSet maintains a sticky identity for each of their Pods. Or just strip the name out to get the index at the end. For example, if you have 3 nodes, it will schedule 3. name of the ReplicaSet is part of the basis for naming those Pods. If the StatefulSet is scaled down to one replica, mysql-3 is guaranteed to exit first, followed by mysql-2. 04 Sep 2023 · 11 min read. 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. EKS is best suited for AWS, so it might be the best option if you are running Kubernetes on AWS. How to run stateful applications in Kubernetes. WEKA. Familiarity with volumes is suggested, in particular PersistentVolumeClaim and PersistentVolume. 每个pod都有自己存储，所以都用volumeClaimTemplates，为每个pod都生成一个自己的存储，保存自己的状态 3. We can now deploy the etcd cluster, which will be a StatefulSet with 3 replicas and two Services, one for internal peer communication between the instances as headless service and another for accessing the cluster externally through the API. Yes, Statefulset is the way to go if the pods need to have their identity defined in some way. Define a Stateful Set with PVC. A simple hack is to parse the hostname of the pod which is in the format of $ (statefulset name)-$ (ordinal). nodeAffinity field (if specified) is taken into consideration by the DaemonSet controller when evaluating the eligible nodes, but is replaced on the created Pod with the node. A StatefulSet is another Kubernetes controller that manages pods just like Deployments. Before you begin You need to have a Kubernetes cluster, and the kubectl. apps. Get Full-Length High-Quality DevOps Tutorials for Free - Subscribe Now. For example, you can only have one Pod named myapp-1234 within the same namespace, but you can have one Pod and one Deployment that are each named. This makes it easier to manage and maintain each component. Comme un Déploiement, un StatefulSet gère des Pods qui sont basés sur une même spécification de conteneur. To check the version, use the kubectl version command. To learn about how to configure probes in Kubernetes,. apps is the apiGroup for the deployment resource. The list of stateful charts using a StatefulSet: $ git grep -li 'kind: *StatefulSet' | awk -F '/' '{print $1}' cockroachdb concourse consul ipfs memcached minio mongodb-replicaset rethinkdbkubectl create -f ssd-storageclass. First, the (1) pod comes up, initialized, and then settles into a “ready” state. September 22, 2021 Topics: Cloud Volumes ONTAP Elementary 8 minute read Kubernetes What Is Kubernetes StatefulSet? A StatefulSet is a Kubernetes API object for managing stateful application workloads. name field. In contrast to that, the Pods deployed by StatefulSet component are NOT identical and deployment is more complex. When you’re deploying an application in Kubernetes, you have a few options to choose from. You can use --help after the subcommand to get additional info about possible parameters (for example: kubectl get nodes --help). So, for example, Kubernetes will only create example-statefulset-5 after example-statefulset-4 is up and running. Compare Kubernetes StatefulSet vs. 28. StatefulSet vs Deployment. StatefulSet で作成された Pod は、それぞれ単一の PV をマウントしています. The last section of the manifest defines our StatefulSet. On deployment level it is not possible, but there is an option to do this indirectly. g. status. $ kubectl apply -f statefulset. 2. Deployment vs Statefulset. Example code for HPA: Deployment is a resource to deploy a stateless application, if using a PVC, all replicas will be using the same Volume and none of it will have its own state. $ export MYSQLPOD. StatefulSet 是用来管理有状态应用的工作负载 API 对象。 StatefulSet 用来管理某 Pod 集合的部署和扩缩， 并为这些 Pod 提供持久存储和持久标识符。. –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. Objectives Create a PersistentVolume referencing a disk in your environment. 1 Answer. 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. Also, you will not have to create a PVCs in advance, and you will be able to scale it easily. Migrate to the apps/v1 API, available since v1. Deploying a. a cache or database cluster even though it may solve your specific situation as. But many times, due to some requirements, users make sure that the pods are deployed in order with persistent storage volume and. if the node becomes unreachable (e. kubectl basics. kubectl get deployment – List one or more deployments. Kubernetes Deployment is a resource that manages a set of identical pods. If there's heavy load, you can set up a HorizontalPodAutoscaler to. Kubernetes is a powerful container orchestration tool that provides a variety of resources. yaml storageclass. This article describes how to create, update, and delete StatefulSets, which are used to maintain the state of an application beyond a pod lifecycle in an Azure Kubernetes Serice deployment in AKS hybrid. replicas integer: Total number of non-terminated pods targeted by this deployment (their labels match the selector). yml Statefulset . api. Gestiona el despliegue y escalado de un conjunto de Pods, y garantiza el orden y unicidad de dichos Pods. StatefulSet has a lot of similar characteristics to a Deployment, and it's scaled like that, it has a pod spec like that, but it is different from Deployment. For simplicity, are we using Nginx as the pod image. Statefulsets. These pods are created from the same spec, but are not interchangeable: each has a persistent identifier that it maintains across any rescheduling. I have tested its working by autoscaling one of my Deployment. The manifest files do not have the namespace added to them. Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. Nota: Los StatefulSets son estables (GA) en la versión 1. Without dynamic provisioning, cluster administrators have to manually make calls to their cloud or storage provider to create new storage volumes, and then create PersistentVolume objects to represent them in Kubernetes. It should be UpdateStrategy. Run a Stateless Application Using a Deployment; Run a Single-Instance Stateful Application; Run a Replicated Stateful Application; Scale a StatefulSet; Delete a StatefulSet; Force Delete StatefulSet Pods; Horizontal Pod Autoscaling; HorizontalPodAutoscaler Walkthrough; Specifying a Disruption Budget for your. yaml You should receive the following output: service/mongo created statefulset. This task shows you how to delete a StatefulSet. 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. This article describes how to create, update, and delete StatefulSets, which are used to maintain the state of an application beyond a pod lifecycle in an Azure Kubernetes Serice deployment in AKS hybrid. The above command will create a ReplicaSet with three replicas and manage the lifecycle of the pods. spec. In this example: A Deployment named nginx-deployment is created, indicated by the . StatefulSet (stable-GA in k8s v1. It manages the. We are going to need the affinity/anti-affinity settings. You can see the metrics in line charts over a period of time under the Monitoring tab. Without dynamic provisioning, cluster administrators have to manually make calls to their cloud or storage provider to create new storage volumes, and then create PersistentVolume objects to represent them in Kubernetes. 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. field to . Each Pod in a StatefulSet derives its hostname from the name of the StatefulSet and the ordinal of the Pod. StatefulSet ensures that, at any time, there is at most one Pod with a given identity running in a cluster. Kubernetes StatefulSet is the workload API object used to manage stateful applications. 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. Storage. To execute our deployment, we need a service to access the above deployment. But each resource type has unique benefits, drawbacks and use cases. Before you begin StatefulSets are only available in Kubernetes version 1. Deployment and StatefulSet are two of the most popular and powerful features of Kubernetes. spec. One of the more powerful features of a StatefulSet is the use of persistent. io. StatefulSet is the workload API object used to manage stateful applications. Furthermore, StatefulSet comes with the capability of running replicas with stable DNS name/entries that target each replica. To check your version of Kubernetes, run kubectl version. To demonstrate just how pervasive the problem is, one can compare the list of charts using a StatefulSet vs a Deployment. Các Pod của Statefuleset không hoàn toàn giống. Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec, but unlike a Deployment, a StatefulSet maintains a sticky. One of the more powerful features of a StatefulSet is the use of persistent. Pods deployed by Deployment are identical and interchangeable, created in random order with random hashes in their Pod names. schedulerName field of the DaemonSet. You should use a HorizontalPodAutoscaler (HPA for short): HPA automatically updates a workload resource (such as a Deployment or StatefulSet), with the aim of automatically scaling the workload to match demand. These pods are created from the same spec, but are not interchangeable: each has a persistent identifier that it maintains across any. A headless service is a service with a service IP, but instead of load-balancing it will return the IPs of our. You can run code in Pods, whether this is a code designed for a cloud. As Trident uses dynamic provisioning, we will specify a StorageClass, which must have been setup. Deployment vs Statefulset. It makes sense also as each Redis instance relies on a configuration file that keeps track of other cluster instances and their roles. In statefulsets each replica pod. When you have an app which requires persistence, you should create a stateful set instead of deployment. yaml You should receive the following output: service/mongo created statefulset. A replica set is a group of MongoDB deployments that maintain the same data set. It offers a framework to manage clusters of hosts running Linux containers,. These priorities does not only happens when a Node becomes unreachable, but at all times, e. The output of the describe command in this example is the following: Name: nginx-app1. 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 deployment process for Deployments is driven by a controller loop, in contrast to DeploymentConfigs which use deployer pods for every new rollout. StatefulSet. One pod should be able to reach other pods with well-defined names. When you use a StatefulSet, Kubernetes terminates Pods in the opposite order to their creation. The Hitchhiker’s Guide to the Galaxy is popular around Prefect. If you are deploying something completely custom and build the docker image. spec. Using a shell script we would call $ {HOSTNAME##*-} to get the index. yaml, we can run the following command to run both of them: kubectl apply -f mongo-statefulset. Deployment is a specialized term in the context of Kubernetes. A StatefulSet is a Kubernetes API object for managing stateful application workloads. They let you ensure that pods are scheduled in a specific order, that they have persistent storage volumes available, and that they have a persistent network ID that is maintained even when a pod shuts down or is rescheduled. template. StatefulSet. Then, the second pod (2) does likewise. Contrairement à un Deployment, un. Hosting. Dynamic volume provisioning allows storage volumes to be created on-demand. Each time a deployment is triggered, whether manually or automatically, a deployer pod manages the deployment (including scaling down the old replication controller, scaling up the new one, and running hooks). The Deployment object not only creates the pods but also ensures the correct. This controller provides stateful storage for persistent applications. StatefulSets manage the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of those Pods. A Kubernetes StorageClass is a Kubernetes storage mechanism that lets you dynamically provision persistent volumes (PV) in a Kubernetes cluster. Deployment and Scaling of StatefulSet. mourya ~ % kubectl get statefulset NAME READY AGE web 3/3 68s. For a rolling update, the Deployment's maxUnavailable will be in effect, even if the PodDisruptionBudget specifies a smaller value. One of the most powerful tools Kubernetes provides in this area are the securityContext settings that every Pod and Container manifest can leverage. The output shows that the Deployment has two Pods. 8 min read. The Stateful Set definition can reference a Service which gives the Pods of the Stateful Set their network identity. This name will become the basis for the ReplicaSets and Pods which are created later. But what is the best for this case ?. 3. Elasticsearch nodes have the same name as the Pod they are running on. StatefulSet and Deployment both aim to maximise availability, however StatefulSet is constrained by its inability to. 5 In the latest release, Kubernetes 1. This document describes the concept of a StorageClass in Kubernetes. I'll try removing some parts of the alertmanager deployment to identify the issue. If. The most common use for a StatefulSet is to be able to make a link between its Pods and their persistent storage. A Kubernetes Deployment YAML specifies the configuration for a Deployment object—this is a Kubernetes object that can create and update a set of identical pods. Autoscaling is a process that dynamically scales up or down any components of your architecture. Statefulset is generally used with a distributed applications that require each node to have a persistent state and the ability to configure an arbitrary. io. A StatefulSet is a workload API object for managing stateful applications. 2. In the process, Karpenter will interpret the requirements of the pods that need to be scheduled and provision nodes that allow for these affinity rules to be met in an optimal way. The deployment process for Deployment objects is driven by a controller loop, in contrast to DeploymentConfig objects which use deployer pods for every new rollout. StatefulSet. fluentd-elasticsearch namespace: kube-system labels: k8s-app: fluentd-logging spec: selector: matchLabels: name. Overview of StatefulSets. 14: kubectl edit pvc <name> for each PVC in the StatefulSet, to increase its capacity. 3. Issue is only with statefulset. Deployment manages creating Pods by means of ReplicaSets. Login to the MySQL pod and Verify: kubectl exec -it mysql-0 -- mysql -u root -p. StatefulSets are designed to run stateful applications in Kubernetes with dedicated persistent storage. Many different settings impact Kubernetes API security, requiring significant knowledge to implement correctly. Version the ConfigMap. You can also use a preexisting disk in a StatefulSet. Note that you must manually create 3 deployments as you can't have a service point to a single pod in a deployment. This naming is consistent, so you. To update a StatefulSet, you can use kubectl, the Kubernetes API, or the GKE Workloads menu in the Google Cloud console. e. It can span multiple Kubernetes clusters under the same monitoring umbrella. Note that this is the default update strategy, but it’s a good practice to declare it. The number of required nodes of our cluster. At this point, the Green Pods retire, and Blue becomes the new Green. However, the administration of stateful applications and distributed systems on Kubernetes is a broad, complex topic. In this article. unknown. – 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. 安定したネットワーク識別子. This is the resource KEDA will scale up/down and setup an HPA for, based on the triggers defined in triggers:. Deployment. StatefulSets are designed to run stateful applications in Kubernetes with dedicated persistent storage. By Chris Tozzi Published: 16 Nov 2022 StatefulSets. Where the reclaim policy is Delete, the expectation is that the storage backend releases the storage resource that. StatefulSet. I agree with you. 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 que veas las diferencias entre Stateful y Stateless en una. Deployment and StatefulSet are two of the most popular and powerful features of Kubernetes. 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. Deployments in k8s do not keep state in their Pods by assuming the application is stateless. When a deployment is created, Kubernetes builds pods to host application. The user can specify a different scheduler for the Pods of the DaemonSet, by setting the . Since my REST WebService endpoints work only on Active node, the service requests work via K8S Service resource only when the request is getting routed to the POD with app in Active role. Refer to the StatefulSet (redis-cluster. 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. updateStrategy is left unspecified. 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:StatefulSet and deployment controllers. vim redis-statefulset. When you use envFrom, all the key-value pairs in the referenced ConfigMap or Secret are set as. 安定したネットワーク識別子. This contains fields that maybe updated both. The three most common are: Rolling update strategy: Minimizes downtime at the cost of update speed. yaml file, you will find a snippet around how we are deploying a stateful application. kubectl get pods NAME READY. Note: This is not a production configuration. ** Notes. A Kubernetes secret for storing the database password. Also, you will not have to create a PVCs in advance, and you will be able to scale it easily. Deployments offer declarative configuration to automate Pod updates and scaling. This page shows how to run a replicated stateful application using a StatefulSet. Kubernetes Deployment. You can also update the object's resource requests and limits, labels, and annotations. 1 Like. 1 Answer. ValidationError(StatefulSet. All of the other parts are ready and we will just plug in the engine and we will be ready to hit the road. Kubernetes persistent volumes (PVs) are a unit of storage provided by an administrator as part of a Kubernetes cluster. Ordering: Kubernetes StatefulSet ensures that each pod is created in a specific order, while Deployment does not. k8s. This is referred to as at most. g. Các Pod của Deployment cũng có thể bị xóa theo thứ tự bất kỳ, hoặc xóa đồng thời nhiều Pod (trong trường hợp scale down deployment) Statefulset. Note: The command field corresponds to entrypoint in some container runtimes. Each new pod in statefulset then have a new PV attached to. The StatefulSet will not even scale until all the required pods are running, so if one dies, it recreates the pod before. 9. For example, to create and check a service configuration for an Nginx application, use the following: kubectl expose deployment/nginx-app1. 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. type is set to RollingUpdate, the. StatefulSet(stable-GA in k8s v1. Deploy and Manages the stateless application. This is required by RabbitMQ for clustering, and as mentioned in the Kubernetes documentation, has to be created before the Stateful Set. Editor's note: today's post is by Janet Kuo and Kenneth Owens, Software Engineers at Google. Different classes might map to quality-of-service levels, or to backup policies, or to arbitrary. Some of the key features of StatefulSets are as follows: 1. Kind of like a watch dog. Pods created as part of a StatefulSet are given persistent identifiers that they retain even when they’re rescheduled. If you don’t specify the namespace, it gets deployed in the default namespace. Deploying a Stateful Application Using Kubernetes Statefulset. mourya ~ % kubectl get statefulset NAME READY AGE web 0/0 33s deepak. Unlike a Deployment, a StatefulSet maintains a. replicas field. The new pods are scheduled on eligible nodes (they may not run on the same nodes as the original pods). 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”. Pods are deployed in {0. Both Deployment and StatefulSet try to maximize the availability - but StatefulSet cannot sacrifice data consistency (e. What I am looking for is to fix a node for an individual pod of a StatefulSet. Let’s look at the StatefulSet, step-by-step. The actual Pod creation is handled by the StatefulSet controller in Kubernetes. Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. Create Some Data. While they have similar goals of managing the lifecycle of a containerized application, they are very different in how they go about it. 1. For example, liveness probes could catch a deadlock, where an application is running, but unable to make progress. In Persistent Volume Claims under Storage, you can see the ClickHouse Cluster components are using persistent volumes. 2. You have few fields which can't be used in statefulset. In this example, we’ve defined a StatefulSet named “my-statefulset” with a headless service named “my-statefulset-headless”. StatefulSets. The user can specify a different scheduler for the Pods of the DaemonSet, by setting the . apps/web scaled deepak. I have tested its working by autoscaling one of my Deployment. Then we run the command for the deployment template : kubectl apply -f demo-deployment. Kubernetes (K8s) es un orquestador de contenedores de código abierto orientado a automatizar la implementación, escalado y administración de aplicaciones en contenedores Docker o CRI-O. However, the order matters in a StatefulSet, and K8s will maintain that order when scaling up or down to ensure stability. However, while Elasticsearch uses terms like cluster and node, which are also used in Kubernetes, their meaning is slightly different. This logic is mandatory in.