Welcome to Day 11 of our #30DaysOfKubernetes journey! Today, we dive into the intricate world of Kubernetes networking, an essential aspect of managing containers in a cluster. Kubernetes networking ensures that your containers can communicate within the cluster and with the outside world. Let’s unravel the complexities of networking in Kubernetes.
Objectives
By the end of this day, you will:
Understand the basics of how pods and containers can communicate within the same pod and node.
Explore the critical role of Service objects in Kubernetes networking.
Gain insights into different Service types, including ClusterIP, NodePort, LoadBalancer, and ExternalName.
Things to know about accessing pods or containers in some scenarios:
- Multiple containers within the pod access each other through a loopback address(localhost).
- The cluster provides communication between multiple pods.
- To access your application from outside of the cluster, you need a Services object in Kubernetes.
- You can also use the Services object to publish services only for access within the cluster.
Access containers within the same pod
apiVersion: v1
kind: Pod
metadata:
name: day10
labels:
env: testing
department: DevOps
spec:
containers:
- name: container1
image: nginx
- name: container2
image: ubuntu
command: ["/bin/bash", "-c", "while true; do echo This is Day07 of 30DaysOfKubernetes; sleep 5 ; done"]
ports:
- containerPort: 80
kubectl exec day07 -it -c container2 — /bin/bash
Update the packages and install the curl
Run the below command.
curl localhost:80
Access containers within the same Node.
apiVersion: v1
kind: Pod
metadata:
name: day10-pod1
labels:
env: testing
department: DevOps
spec:
containers:
- name: container1
image: nginx
ports:
- containerPort: 80
apiVersion: v1
kind: Pod
metadata:
name: day10-pod2
labels:
env: testing
department: DevOps
spec:
containers:
- name: container2
image: httpd
ports:
- containerPort: 80
Service Object in Kubernetes
To configure Networking for deployed applications on pods and containers, we use Service objects.
There are four main types of Kubernetes Services:
- ClusterIP: As the name suggests, With the help of this Service. Kubernetes expose the service within the cluster which means the service or application won’t be accessible outside of the cluster. You can view the Service YML file and see how to use this service.
apiVersion: v1
kind: Service
metadata:
name: httpd-service
spec:
ports:
- port: 80
targetPort: 80
selector:
name: DevOps
type: ClusterIP
2. NodePort: This is the next stage of the ClusterIP where you want to deploy your application or service that should be accessible to the world without any interruption. In this Service, the node port exposes the service or application through the static port on each node’s IP. You can view the Service YML file and see how to use this service.
apiVersion: v1
kind: Service
metadata:
name: httpd-service
spec:
ports:
- port: 80
targetPort: 80
selector:
name: DevOps
type: NodePort
3. LoadBalancer: Load balancers are used to distribute the traffic between the multiple pods. With the help of this service object, the services will be exposed via the cloud’s load balancer. You can view the Service YML file and see how to use this service.
apiVersion: v1
kind: Service
metadata:
name: svc-lb
spec:
type: LoadBalancer
selector:
tag: DevOps
ports:
- name: port-lb
protocol: TCP
port: 80
targetPort: 80
4. ExternalName: This is a similar object service to ClusterIP but it does have DNS CName instead of Selectors and labels. In other words, services will be mapped to a DNS name. You can view the Service YML file and see how to use this service.
apiVersion: v1
kind: Service
metadata:
name: k8-service
namespace: dev
spec:
type: ExternalName
externalName: k8.learning.com
Conclusion
Understanding Kubernetes networking is crucial for managing containers effectively. With knowledge of how to access containers within the same pod and the versatility of Service objects, you’re well on your way to becoming a Kubernetes networking expert.
Stay tuned for more exciting Kubernetes insights in our #30DaysOfKubernetes journey!
Want to Know About Challenge?
If you’re eager to learn more and join our challenge through the GitHub Repository, stay tuned for the upcoming posts. Follow for more exciting insights into the world of Kubernetes!
GitHub Repository: https://github.com/AmanPathak-DevOps/30DaysOfKubernetes
#Kubernetes #ReplicationController #ReplicaSet #ContainerOrchestration #DevOps #K8sLearning
See you on Day 11 as we unravel more Kubernetes mysteries!
Stay connected on LinkedIn: LinkedIn Profile
Stay up-to-date with GitHub: GitHub Profile
Feel free to reach out to me, if you have any other queries.
Happy Learning
