STatefulSet Typical applications list - unix1998/technical_notes GitHub Wiki

StatefulSets are designed for applications that require stable, unique network identifiers and persistent storage. While databases are the most common use case, there are several other applications that benefit from the features of StatefulSets. Here are some examples:

1. Databases

• MySQL
• PostgreSQL
• Cassandra
• MongoDB
• Redis (when persistence is required)

2. Distributed Systems

• Zookeeper: Often used for configuration management, synchronization, and naming registry.
• Etcd: A key-value store used for configuration management and service discovery.
• Consul: A service mesh solution providing service discovery, configuration, and segmentation.

3. Big Data and Analytics

• Hadoop HDFS (Hadoop Distributed File System): Used for scalable, distributed storage.
• Elasticsearch: A search and analytics engine, often used for log and event data.
• Kafka: A distributed streaming platform that requires persistent storage for log data.

4. Messaging Systems

• RabbitMQ: A message broker that requires persistent storage to ensure message delivery and reliability.

5. Content Management Systems

• WordPress (when configured with a persistent backend like MySQL)

6. Continuous Integration/Continuous Deployment (CI/CD) Tools

• Jenkins (when Jenkins data persistence is required)

7. Monitoring and Logging Systems

• Prometheus: A monitoring system that can benefit from persistent storage to retain historical metrics data.

Example of a StatefulSet YAML

Here’s an example of a StatefulSet configuration for a MySQL database:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  serviceName: "mysql"
  replicas: 3
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:5.7
        ports:
        - containerPort: 3306
          name: mysql
        volumeMounts:
        - name: mysql-persistent-storage
          mountPath: /var/lib/mysql
  volumeClaimTemplates:
  - metadata:
      name: mysql-persistent-storage
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 1Gi

Why Use StatefulSet?

StatefulSets are beneficial for these applications because they provide:

• Stable Network Identities: Each pod in a StatefulSet has a unique, stable hostname, which is crucial for clustered applications.
• Stable Storage: Each pod can have its own persistent storage, which is not affected by the lifecycle of the pod.
• Ordered, Graceful Deployment and Scaling: Pods are created, deleted, or scaled in a defined order, ensuring the correct initialization and shutdown sequence.

In summary, while databases are a primary use case, any stateful application that requires stable identities and persistent storage can benefit from using StatefulSets.