Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. In part 1 of this series, we discussed the difficulties of managing a Kubernetes cluster, the challenges of conventional monitoring approaches in ephemeral environments, and what our goals should be as we think about how to approach Kubernetes monitoring. As we’ve seen, each pod in a StatefulSet gets assigned its. Open an issue in the GitHub Repository if you want to report a problem or suggest an improvement. Clients such as tools and libraries can retrieve this metadata. 2. StatefulSets vs. Unlike a Deployment, a StatefulSet. updateStrategy field, by waiting for each pod. We recommend making pods that reference volumes owned by a StatefulSet. ReplicaSet is a lower-level abstraction that provides basic scaling mechanisms. Kubernetes (K8s) is one of the popular open-source container orchestration systems for automating deployment, scaling, and management of containerized applications. The Reclaim Policy is used to determine the actions that need to be taken by the storage backend on deletion of the PV. 7 and later, the StatefulSet controller supports automated updates. 5 and becoming stable in 1. yamlDescription. It manages the deployment and scaling of a set of Pods and provides the guarantee about the ordering and uniqueness of these Pods. A bare metal deployment of the collector is simple to plan and execute: it’s a single binary that runs as a daemon on the host. Đây là bài thứ 9 trong series của mình, ở những bài trước chúng ta đã dùng Pod, ReplicaSet, Deployment để deploy một ứng dụng hoặc nhiều ứng dụng mà chạy chung một template để tăng performance. Creating a Service to Expose our Blog. The Deployment controller and Job controller are examples of controllers that come as part of Kubernetes itself ("built-in" controllers). They give Pods a stable identity and consistent ordering during scaling operations. StatefulSet is also a Controller but unlike Deployments, it doesn’t create ReplicaSet rather itself but creates. 9) is a Kubernetes resource used to manage stateful applications. Definitely leverage a persistent volume for database. Unlike a Deployment, a StatefulSet. It takes the statefulset name and the desired number of replicas as arguments. Here you can see how the Deployment itself runs a ReplicaSet that then runs 3 pods. Feedback. Using these replicas, we can have fast failover of the Kafka nodes and eliminate the I/O load during. While the pod is the basic deployment unit for containers, Kubernetes provides various resource objects for orchestrating multiple pod replicas. In Kubernetes, a Pod represents a set of running containers on your cluster. StatefulSet. StatefulSet is the workload API object used to manage stateful applications. Kubernetes Tutorial for Beginners. yaml kubectl apply -f service. 5 In the latest release, Kubernetes 1. g. This will expose ghost deployment on port 80 as ghost-blog-service. These pods are created from the same spec, but are not interchangeable: each has a persistent identifier that it maintains across any rescheduling. The state information and other resilient data for any given StatefulSet pod are stored in the persistent disks of the StatefulSet. Un controlador de Deployment proporciona actualizaciones declarativas para los Pods y los ReplicaSets. The support for autoscaling the statefulsets using HPA is added in kubernetes 1. Therefore, Kubernetes may, at any point, just kill one of your instances and redeploy it elsewhere on the cluster when necessary. Administrators use deployments to specify what they want to happen with their applications. Similar to deployments, StatefulSets manage pods with identical container specifications. 2. This ensures the highest data quality and completeness, and also allows the Collector to leverage the Prometheus ecosystem of exporters to scrape targets. A Kubernetes pod is a cluster deployment unit that typically contains one or more containers. We are going to use the Prometheus Operator to: Perform the initial installation and configuration of the full Kubernetes-Prometheus stack. Labels can be used to select objects and to find collections of. using ClusterIP services). Summary. We often say that for stateful apps you need to use StatefulSet and for stateless apps a Deployment. Get Full-Length High-Quality DevOps Tutorials for Free - Subscribe Now. Deployments: It is used for “stateless applications”. It can be used to manage three Kubernetes objects: Deployment, DaemonSet, and. Kubernetes Deployment vs StatefulSet. Learn how Kubernetes Deployments and StatefulSets are used to automatically provision applications, and which will work best for your use case. A StatefulSet is another Kubernetes controller that manages pods just like Deployments. You can use --help after the subcommand to get additional info about possible parameters (for example: kubectl get nodes --help). This page shows how to run a replicated stateful application using a StatefulSet. Ordered, graceful deletion and termination. Sorted by: 21. It seems to support some of the same features of a ReplicationController - scale up/down and auto restart, but it's not clear if it supports rolling upgrades or autoscale. Welcome to a comprehensive journey into the heart of Kubernetes deployment strategies – StatefulSets and Stateless Deployments. Suppose you see the pods using the kubectl get pods command. They. This name will become the basis for the ReplicaSets and Pods which are created later. On-disk files in a Container are ephemeralStatefulSet is a Kubernetes controller used to deploy stateful apps. Kubernetes is Google’s open-source solution for running distributed workloads. externalTrafficPolicy: Local. Deployment with name backend is created indicated by metadata. Kubernetes StatefulSet is a resource that manages a set of identical stateful pods. StatefulSet. Each new pod in statefulset then have a new PV attached to. A Kubernetes StorageClass is a Kubernetes storage mechanism that lets you dynamically provision persistent volumes (PV) in a Kubernetes cluster. . One pod should be able to reach other pods with well-defined names. イメージ的にはPodTemplateを持つDeploymentにPVCも追加した感じ。. In Kubernetes, a Deployment is a workload resource object that lets you configure the lifecycle of pods in the cluster. 8 user guide shows how to create a deployment in. It provides ordered pod creation, stable network identities, and persistent storage for each pod in the set. We explore these features using Apache ZooKeeper and Apache Kafka StatefulSets and a Prometheus node exporter. StatefulSetの概要. Session affinity is achieved by enabling “sticky sessions,” allowing clients to go back to the same instance as often as possible, which helps. Not all stateful applications scale nicely. Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. This name will become the basis for the ReplicaSets and Pods which are created later. If the zk-0 and zk-1 Pods were deployed on the same node, and that node failed, the ZooKeeper ensemble couldn’t form a quorum to commit writes, and the ZooKeeper service would experience an outage until one of the Pods. io/hostname ). Author: Matthew Cary (Google) Kubernetes v1. a cache or database cluster even though it may solve your specific situation as. Statefulsets. 2 Answers. Author: Chris Henzie (Google) Last month's release of Kubernetes v1. Conclusion. Các Pod của Statefulset không thể được tạo hay xóa cùng lúc. It is particularly useful for managing databases, message brokers, and other stateful services. yml 4. The StatefulSet controller is responsible for creating, scaling and deleting members of the StatefulSet. For Kubernetes, however, we have a few options to pick from:The topologySpreadConstraints policy in the StatefulSet specification (c1-mysql. Why use StatefulSets. 1 Answer. I am trying to convert one Deployment to StatefulSet in Kubernetes. zk-hs. yml └── keycloak-statefulset. Kubernetes will automatically pick Docker as the default container runtime. The functions that this framework enables vary widely from one database deployment to another. To improve fault tolerance, instead, they should always be part of a Deployment, DaemonSet, ReplicaSet or StatefulSet. StatefulSets. I didn't really talk about (3) and (4) but that can also help with clusters as you can tell the first one to deploy to become the master and the next one find the first and treat it as master, etc. You make sure to bind a volume to your database container. ; StatefulSet - You specify a volumeClaimTemplates so that each replica pod gets a. Kubernetes Services: Pods exposed1 Answer. If you are unsure about whether to scale your StatefulSets, see StatefulSet concepts. default. kubectl get statefulset. The manifest files do not have the namespace added to them. io. Deploymentなど、StatefulSet以外のリソースを使う必要がある。 以下の記事がわかりやすい。 参考：KubernetesのStatefulSetを疑ってみたが濡れ衣だった. However, these features only resolve part of Pods distribution use cases: either place unlimited Pods to a. Author: Wei Huang (IBM), Aldo Culquicondor (Google) Managing Pods distribution across a cluster is hard. In the previous section, we described the Headless Service. After learning that we should have used a StatefulSet instead of a Deployment in order to be able to attach the same persistent volume to multiple pods and especially pods on different nodes, I tried changing our config accordingly. Deployment. kubectl scale statefulset: This command is used to scale the number of replicas for a statefulset in a Kubernetes cluster. metadata. yaml kubectl apply -f statefulset. Their purpose is to keep a set of identical pods running and upgrade them in a controlled way. StatefulSet. However, the administration of stateful applications and distributed systems on. Kubernetes StatefulSet is the workload API object used to manage stateful applications. StatefulSet is a Kubernetes controller that manages multiple pods that have unique identities, and are not interchangeable (unlike a regular Kubernetes Deployment, in which pods are stateless and. Por ejemplo, si creamos un StatefulSet con el nombre counter, se creará un pod con el nombre counter-0, y para múltiples réplicas de un StatefulSet, sus nombres se incrementarán. If Kubernetes is the new operating system, then a pod is the new process. Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. targetPort: 80. It gives the pods sequential names, starting with statefulsetname-0; and. There isn't really a supported way to do this cluster-wide. Overview of StatefulSets. To successfully deploy a MySQL instance on Kubernetes, create a series of YAML files that you will use to define the following Kubernetes objects:. Kubernetes is an open-source platform that automates the deployment, scaling, and management of containerized applications. Next Steps. Here, we dive deeper into using this API object to manage stateful applications. See Writing a Deployment Spec for more details. default. . The Kubernetes manifest above is also deploying an Nginx application except for this time, you’ll see a few new pieces including: The kind is now StatefulSet; There are volumes; Mount paths exist to store the data; Let’s talk about the Deployment spec and StatefulSet differences. Deploying a MongoDB Database: Here is an example of how to deploy a MongoDB database using a StatefulSet in Kubernetes. a cache or database cluster even though it may solve your specific situation as. The reference to the resource this ScaledObject is configured for. I'm using Logstash on Kubernetes and use the official Helm chart at this link. This post talks about recent updates to the DaemonSet and StatefulSet API objects for Kubernetes. . Manages the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods. Thanks for the feedback. The Deployment creates a ReplicaSet that creates three replicated Pods, indicated by the. 3 Gi of memory. Create a ConfigMap YAML file in a. We can expose our application to the internet with the following command: $ kubectl expose deployment ghost-blog --type="LoadBalancer" --name=ghost-blog-service --port=80 --target-port=2368. The strategy used is determined by the spec. The cluster state in Kubernetes is defined by resource definitions, written as manifest files, that specify the internal behavior of the cluster. Deployment vs. Using a statefulset also ensures that. Editor’s note: this post is part of a series of in-depth articles on what's new in Kubernetes 1. This is a simple example of the above one. Kubernetes defines many different resources and Controllers that manage them. Before understanding StatefulSets, you must understand Kubernetes Deployment. there are a few things you can do with a DeploymentConfig (around triggers) that you can't do. The stable hostname is generated from the name of the StatefulSet and the ordinal number of the pod in the set. Stateful app (1 instance) On the diagram above we can see a StatefulSet that generates a Pod which mounts a disk provided by the PVC/PV pair. metadata. Deploy the workloads on kubernetes. Additionally, we are creating a Persistent Volume using the volumeClaimTemplate and using it in the StatefulSet to store the PostgreSQL data. In Kubernetes, one method of managing these actions is by using StatefulSets. Use kubectl apply -f <directory>. Editor's note: today's post is by Janet Kuo and Kenneth Owens, Software Engineers at Google. In this example: A Deployment named nginx-deployment is created, indicated by the . Click Services, and then click Add Service. yamlI get many questions about Kubernetes and persistence. StatefulSet (stable-GA in k8s v1. Kubernetes maintains these pods regardless of whether pods are scheduled. your peers. Statefulsets and Operators are not that similar. 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. Just as a node is a compute resource used by the cluster, a PV is a storage resource. This page shows how to run a replicated stateful application using a StatefulSet. A local persistent volume serves as a. StatefulSet is used to manage stateful applications: It manages the deployment and scaling of a set of Pods. 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. In this example, we will create a PostgreSQL deployment as a StatefulSet with a persistent storage volume. These pods are created from the same spec, but are not interchangeable: each has a persistent identifier that it maintains across any rescheduling. Podname and Identity. Prometheus servers. Represents the latest available observations of a statefulset’s current state. zk-hs. Manual configuration of Postgres on Kubernetes allows you to fine-tune your deployment configuration. 9. Due to this issue¹ automatic rollback in case of failed upgrade is not possible. A StatefulSet is the Kubernetes controller used to run the stateful application as containers (Pods) in the Kubernetes cluster. By default, Kubernetes runs one instance for each Pod you create. svc. On an update the existing Pods will get deleted and recreated. The most basic difference is that you would get ability to persist pod level state with statefulsets. Just like StatefulSets, Kubernetes Deployments let you define the state of the application, and the Deployment’s controller is responsible for maintaining this state. Use label selectors for get and delete operations instead of specific object names. The example topology has a single primary server and multiple replicas, using asynchronous row-based replication. Here we use an image that will run the Nginx web server: kubectl. Totally agree with you i have been thinking about this recently as well, yes as a part of Kubernetes 1. Remember that you can choose any namespace of your choice here. StatefulSet Kubernetes | Understand what StatefulSet in Kubernetes is and how it worksUsing StatefulSet in practice 🙅🏼♀️ Deployment (default mode) The default method - the Deployment mode, will be used here. Storage classes can define properties of storage systems. The StatefulSet guarantees stable network identity for each instance. template field of the YAML configuration. However, even when using the same name for the volume claim as before, it seems to be creating an. g. These priorities does not only happens when a Node becomes unreachable, but at all times, e. Kubernetes has become the de-facto orchestration tool and initially it was supporting stateless applications, but stateful (data-driven) applications are very common and are critical to almost all the businesses. In most cases, users ignore how their pods are scheduled. A StatefulSet ensures ordered, predictable deployment and scaling of stateful applications. This blog post will discuss how this feature can be used. For a StatefulSet with N replicas, when Pods are being deployed, they are created sequentially, in order from {0. This creates a physical and logical grouping of your applications in Cluster. Cloud Observability recommends running the OpenTelemetry Collector with the Prometheus receiver to ingest infrastructure metrics. StatefulSets vs. A StatefulSet manages Pods that are based on an identical container spec. In Elasticsearch, for example, indexes are broken up into shards. 5. Kubernetes Deployment is a resource that manages a set of identical pods. Manages the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods. If you don’t specify the namespace, it gets deployed in the default namespace. Unlike a Deployment, a StatefulSet maintains a sticky, persistent identity for each of their Pods. This comes at a cost of slow scale ups and. pod-1 can only read a subset of the data and write to a. I read a bit about Deployment vs StatefulSet in Kubernetes. 1. The Deployment creates a ReplicaSet that creates three replicated Pods, indicated by the. If you are writing data on one MySQL Pod, do not replicate the same data on another MySQL Pod if the Pod is restarted. #Deployment vs. It is an ordered. By interpreting the documentation, it seems that it depends on the event. Operators are software extensions to Kubernetes that make use of custom resources to manage applications and their components. You should read about Kubernetes autoscaling - HPA. Now, I have a task to introduce persistence for RabbitMq. This means that each Pod in a StatefulSet has a stable network identity and persistent storage, which are essential for. 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. Likewise, StatefulSets are a great choice for assigning unique. Scaling a StatefulSet refers to increasing or decreasing the number of replicas. Its main purpose. Ordinal Index. Unlike a Deployment, a StatefulSet. metadata. The volume (PVC) is shared across the pods. type: LoadBalancer. kubectl create -f statefulset. Các Pod của Statefulset không thể được tạo hay xóa cùng lúc. Let's look at the top 4 Kubernetes DaemonSet Alternatives you can use. Then, the second pod (2) does likewise. The update strategy is configured using the updateStrategy field. I’d suggest you have 3 Kubernetes Nodes with at least 4GB of RAM and 10GB of storage. Migrating stateful applications from deployment to statefulset is one of the best way to start getting feedback from users. Ordered, graceful deletion and termination. Podname and Identity. It creates a selector that matches to matchLabels. Unlike the average Kubernetes pods, pods within a StatefulSet have a unique index and a stable network identity that is published through a Headless Service. For a typical Kubernetes Pod, it will be managed by a higher-level controller like a Deployment. kubectl get pods. In Kubernetes, scheduling refers to making sure that Pods are matched to Nodes so that the kubelet can run them. This means that each pod has its own IP address, making. Keycloak URL. A. kubectl is the command line interface (CLI) that allows you to manage Kubernetes clusters. StatefulSets are particularly useful when you have stateful applications, such as databases, that require stable network identities and persistent storage. Note: While ReplicaSets can be used, Kubernetes recommends using Deployments. These can be used to make sure that a pod. Deployments and ReplicationControllers are meant for stateless usage and are rather lightweight. While Kubernetes StatefulSet offers a host of options to manage stateful applications. The updateStrategy field accepts one of the following value. It is not advisable to run multiple replicas of the same release of pihole using a deployment because of the same shared underlying storage; It is, however, possible to run multiple different releases of pihole (e. Here is what the above statefulset does: Set 3 replicas. Rolling Update Strategy. 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. Seperti halnya Deployment,. cluster. io/zone). Al igual que un Deployment, un StatefulSet gestiona Pods que se basan en una especificación idéntica de contenedor. Take Assessment. 26 introduced a new, alpha-level feature for StatefulSets that controls the ordinal numbering of Pod replicas. If you run a single instance database server, that would fit the above example. Deploying Stateful Applications is not staright forward as Stateless Applications. updateStrategy field of the StatefulSet API Object. We handle web applications on a growing bare metal k8s deployment, mostly attached to a pvc in rwo access mode (file storage). If your application needs to be brought up in a specific order, use statefulset. The hostnames take the form <statefulset name>-<ordinal index>. StatefulSets will represent the set of pods with different (unique), persistent identities, and elastic hostnames (stable). Manages the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods. But it differs from a Deployment in that it is more suited for stateful apps. Deployment with Node Selector. For any other case, it’s recommended that you use a Deployment. A StatefulSet works like a Deployment, but it maintains the identity of each of its pods. 27, this feature is now beta. Like a Deployment, a StatefulSet. There seems to be general confusion as to when you should use a Deployment with a PVC and when you should use a StatefulSet with a PVC. In other words, shared volume. Deploying it as a statefulset works very similar to a deployment. $ kubectl create ns redis $ kubectl apply -f redis-service. We will then deploy a Kafka StatefulSet which uses our ZooKeeper cluster and also has Portworx volumes with 3 replicas. It tries to ensure that the specified number of Pods from ordinal 0 through N-1 are alive and ready. Recreate Strategy. io/hostname" to deploy the redis cluster so that no two instances are located on the same host You can simply define three replicas of specific pod and define particular pod configuration file, egg. Name Stays the Same. Apr 6, 2020 at 8:53. StatefulSet represents a set of pods with consistent identities. Read: Kubernetes vs Docker Swarm. Main difference (besides that one is using ReplicationController and the other using ReplicaSet as you rightly pointed out) is that. We create a 02-kafka. In Kubernetes, you configure dynamic provisioning by creating a StorageClass. This ensures the highest data quality and completeness, and also allows the Collector to leverage the Prometheus ecosystem of exporters to scrape targets. Manages the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods. In this exhaustive blog post, we will unravel these strategies layer by layer, backed by real-world scenarios and meticulously explained code examples. Thats said, this is an easier solution, and that let you easier scale up to more replicas: When using StatefulSet and PersistentVolumeClaim, use the volumeClaimTemplates: field in the StatefulSet instead. Azure Pipelines has two tasks for working with Kubernetes: KubernetesManifest task: bake and deploy manifests to Kubernetes clusters with Helm, Kompose, or. It provides features such as rolling updates, rollbacks, and scaling of the number of. default. also during upgrades and. In this documentation you will learn how HPA works, how to use it, what is. 1. Comme un Déploiement, un StatefulSet gère des Pods qui sont basés sur une même spécification de conteneur. StatefulSets are used when state has to be persisted. 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. 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). Deploying a Kafka Broker. 0. It is easy to set up and helps minimize your management burden. ; A Persistent Volume. Learn more in the detailed guide to Kubernetes Statefulset. Each with their own semantics. StatefulSet is a controller in Kubernetes that allows users to manage pods the same as the deployments. StatefulSet is the workload API object used to manage stateful applications. One reason is that your coredns or kube-dns use dnsPolicy: Default and not the default dnsPolicy: ClusterFirst so changing it cluster-wide might affect your coredns/kube-dns pods. yml ├── keycloak-service. Deploy PostgreSQL by Creating Configuration from Scratch. The problem is : a Pod will not be re-created after the Node failure (like a reboot). It manages the lifecycle of pods and provides a way to scale and maintain the desired state of the application. You can also run EKS on Outposts for on-premises workloads. Statefulset. Namespace in Kubernetes is intended to work as the separation between scope & functionalities of System. StatefulSets. StatefulSet was released in the Kubernetes 1. 1. StatefulSetには以下のような特徴がある。. The StatefulSet guarantees that a given network identity will always map to the same storage identity. If you have a specific, answerable question about how to use Kubernetes, ask it on Stack Overflow. This is where PersistentVolumes come into. 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. You can use kubectl to deploy applications, inspect and manage cluster. Manages the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods. 9. Kubernetes provides a basic resource called Pod. StatefulSets are Kubernetes objects used to consistently deploy stateful application components. Feedback. Introduction Managing storage is a distinct problem from managing compute instances. Kubernetes (K8s)is an open-source container orchestration system. Kubernetes provides Deployments for managing application orchestration. We will create the “ redis ” namespace then apply the file. But what is the best for this case ? E. It tries to ensure that the specified number of Pods from ordinal 0 through N-1 are alive and ready. Identities are defined as: Network: A single stable DNS and hostname. ; A Persistent Volume (PV) to allocate storage space for the database. It provisions the application pods in an order. Manages the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods. If the zk-0 and zk-1 Pods were deployed on the same node, and that node failed, the ZooKeeper ensemble couldn’t form a quorum to commit writes, and the ZooKeeper service would experience an outage until one of the Pods. When you use a StatefulSet, Kubernetes terminates Pods in the opposite order to their creation. Pods in StatefulSets are not interchangeable: each. In this post, we will list and describe each commonly used category or component of Kubernetes (K8S) with appropriate kubectl commands for quick reference! kubectl is a Kubernetes command-line tool that allows you to run commands against Kubernetes clusters. yml, and . 5 In the latest release, Kubernetes 1. A more complex use case is to run several identical replicas of a replicated service, such as web servers. io/hostname operator: In values: - docker-desktop SC kind: StorageClass apiVersion: storage. The difference between StatefulSets and Deployments reflects the divide between stateful and stateless systems. template field of the YAML configuration. A StatefulSet is a controller that helps you deploy and scale groups of Kubernetes pods. Ordinals can start from arbitrary non-negative numbers. For example, you define how many replicas ( pods) of your app you want to run in the deployment. When pods run as part of a StatefulSet, Kubernetes keeps state data in the persistent storage volumes of the StatefulSet, even if the pods shut down. Author: Peter Schuurman (Google) Kubernetes v1. This page shows how to create a Kubernetes Service object that exposes an external IP address. They each have their own sticky identity, which they. Can I do it with Deployment?I don't see any problem with this. Lines beginning with a '#' will be ignored, # and an empty file will abort the edit. The last section of the manifest defines our StatefulSet. The podAntiAffinity policy enforces the constraint that Pods are required to not be placed on the same GKE cluster node ( kubernetes. Just like StatefulSets, Kubernetes Deployments let you define the state of the application, and the Deployment’s controller is responsible for maintaining this state. It seems that the service is used for 2 purposes: expose the deployment to the outside world (e.