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ReplicaSet YAML

Learn the ReplicaSet YAML structure.

ReplicaSet YAML

The ReplicaSet YAML is very similar to the Deployment's; only kind differs and there's no strategy field:

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: api
spec:
  replicas: 3
  selector:
    matchLabels:
      app: api
  template:
    metadata:
      labels:
        app: api
    spec:
      containers:
        - name: api
          image: api:1.0

ReplicationController

In old sources you may see ReplicationController (rc); it's the ReplicaSet's predecessor and supports only equality-based selectors. It isn't used in new configurations:

# old
kind: ReplicationController
spec:
  selector:
    app: api
# new
kind: ReplicaSet
spec:
  selector:
    matchLabels:
      app: api

Practice ReplicaSet YAML

Write a ReplicaSet YAML: name api, replicas: 3; selector and template label app: api; container named api, image api:1.0.

Starter code

terminal
# buraya yaz

Sample solution

terminal
apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: api
spec:
  replicas: 3
  selector:
    matchLabels:
      app: api
  template:
    metadata:
      labels:
        app: api
    spec:
      containers:
        - name: api
          image: api:1.0

Expected output

replicaset.apps/api created

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What is the ReplicaSet's apiVersion?

  • batch/v1
  • replicaset/v1
  • apps/v1 Correct answer
  • v1

Explanation: Deployment, ReplicaSet, StatefulSet and DaemonSet are in the apps group.

2 Write the object type.

Question 
apiVersion: apps/v1
kind: ____
Answer 
apiVersion: apps/v1
kind: ReplicaSet

Explanation: Type names are case-sensitive.

3 Match.

Term Meaning
ReplicaSet apps/v1
ReplicationController Old predecessor
matchLabels Label matching
template Pod mould

All lessons in Intermediate

1 What is Kubernetes?

  1. What is Kubernetes?
  2. Why Kubernetes?
  3. Cluster architecture
  4. Control plane
  5. Worker node
  6. Summary - What is Kubernetes

2 Minikube

  1. What is Minikube?
  2. Installing Minikube
  3. minikube start
  4. minikube status
  5. minikube dashboard
  6. Summary - Minikube

3 kubectl basics

  1. What is kubectl?
  2. kubectl get
  3. kubectl describe
  4. kubectl apply
  5. kubectl delete
  6. Summary - kubectl

4 Pod

  1. What is a Pod?
  2. Pod YAML
  3. Creating a Pod
  4. Pod status
  5. Multi-container Pod
  6. Summary - Pod

5 Deployment

  1. What is a Deployment?
  2. Deployment YAML
  3. Replica count
  4. Rolling update
  5. Rollback
  6. Summary - Deployment

6 ReplicaSet

  1. What is a ReplicaSet?
  2. ReplicaSet YAML
  3. ReplicaSet selector
  4. Scaling
  5. Self-healing
  6. Summary - ReplicaSet

7 Service

  1. What is a Service?
  2. ClusterIP
  3. NodePort
  4. LoadBalancer
  5. Service selector
  6. Summary - Service

8 ConfigMap

  1. What is a ConfigMap?
  2. ConfigMap YAML
  3. Environment variable
  4. Mounting as a volume
  5. kubectl create configmap
  6. Summary - ConfigMap

9 Secret

  1. What is a Secret?
  2. Secret types
  3. Secret YAML
  4. Mounting a Secret
  5. kubectl create secret
  6. Summary - Secret

10 Namespace

  1. What is a Namespace?
  2. kubectl get namespaces
  3. Creating a Namespace
  4. The -n flag
  5. Default Namespace
  6. Summary - Namespace

11 Labels and selectors

  1. What is a label?
  2. Adding labels
  3. Label selector
  4. kubectl get -l
  5. Equality and set selectors
  6. Summary - Labels

12 Project: Multi-tier app

  1. Project design
  2. Database Deployment
  3. Web Deployment
  4. ConfigMap and Secret
  5. Putting it together - multi-tier

13 Troubleshooting

  1. kubectl logs
  2. kubectl exec
  3. kubectl describe pod
  4. CrashLoopBackOff
  5. Pending Pod
  6. Summary - Troubleshooting

14 Intermediate final

  1. Challenge - Pod YAML
  2. Challenge - Deployment
  3. Challenge - Service
  4. Challenge - ConfigMap
  5. Challenge - Intermediate project