Kubernetes - Stateful Sets 🌟

Description 👀

Stateful sets are used to manage stateful applications. They are similar to deployments but they provide guarantees about the ordering and uniqueness of the pods they create. Stateful sets are useful for applications that require one or more of the following. Stable, unique network identifiers. Stable, persistent storage. Ordered, graceful deployment and scaling. Ordered, automated rolling updates.

Basic Commands 📝

• scale a stateful set

    kubectl scale statefulset <stateful-set-name> --replicas=<number-of-replicas>
  

Examples 🧩

• stateful set definition

    apiVersion: apps/v1
    kind: StatefulSet
    metadata:
        name: mysql
        labels:
            app: mysql
    spec:
        replicas: 3
        selector:
            matchLabels:
                app: mysql
        serviceName: mysql-h
        # causes the pods to be created in parallel, rather than sequentially. will maintain all of its other properties.
        podManagementPolicy: Parallel
        template:
            metadata:
                labels:
                    app: mysql
            spec:
                containers:
                  - name: mysql
                    image: mysql
  

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