Kubernetes Hands-on Lab #1 – Setting up 5-Node K8s Cluster

Estimated Reading Time: 4 minutes

 

Are you new to Kubernetes? Want to build your career in Kubernetes? Then Welcome ! You are at the right place. This blog post series brings you tutorials that help you get hands-on experience using Kubernetes. Here you will find a mix of labs and tutorials that will help you, no matter if you are a beginner, SysAdmin, IT Pro or Developer. Yes, you read it correct ! Its $0 learning platform. You don’t need any infrastructure. Most of the tutorials runs on Play with K8s Platform. This is a free browser based learning platform for you. Kubernetes tools like kubeadm, kompose & kubectl are already installed for you. All you need is to get started.

Kubernetes (often abbreviated to K8S), is a container orchestration platform for applications that run on containers. Kubernetes is an open-source system for automating deployment, scaling, and management of containerized applications. It groups containers that make up an application into logical units for easy management and discovery.

Kubernetes can speed up the development process by making easy, automated deployments, updates (rolling-update) and by managing our apps and services with almost zero downtime. It also provides self-healing. Kubernetes can detect and restart services when a process crashes inside the container. Any developer can package up applications and deploy them on Kubernetes with basic Docker knowledge.

At a minimum, Kubernetes can schedule and run application containers on clusters of physical or virtual machines. However, Kubernetes also allows developers to ‘cut the cord’ to physical and virtual machines, moving from a host-centric infrastructure to a container-centric infrastructure, which provides the full advantages and benefits inherent to containers. Kubernetes provides the infrastructure to build a truly container-centric development environment. K8s provides a rich set of features for container grouping, container orchestration, health checking, service discovery, load balancing, horizontal autoscaling, secrets & configuration management, storage orchestration, resource usage monitoring, CLI, and dashboard.

This is the first blog targeted at setting up 5-Node Kubernetes cluster. To get started with Kubernetes, follow the below steps:

Click on “Start” button to get access to PWK instances as shown below:

Click on Add Instances to setup first k8s node.

Cloning the Repository

git clone https://github.com/ajeetraina/kubernetes101/
cd kubernetes101/install

Bootstrapping the First Node Cluster

sh bootstrap.sh

Adding New K8s Cluster Node

Click on Add Instances to setup first k8s node cluster

Wait for 1 minute time till it gets completed.

Copy the command starting with kubeadm join ..... We will need it to be run on the worker node.

Setting up Worker Node

Click on “Add New Instance” and paste the last kubeadm command on this fresh new worker node.

[node2 ~]$ kubeadm join --token 4f924f.14eb7618a20d2ece 192.168.0.8:6443 --discovery-token-ca-cert-hash  sha256:a5c25aa4573e06a0c11b11df23c8f85c95bae36cbb07d5e7879d9341a3ec67b3```

You will see the below output:

[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
[preflight] Skipping pre-flight checks[discovery] Trying to connect to API Server "192.168.0.8:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://192.168.0.8:6443"
[discovery] Requesting info from "https://192.168.0.8:6443" again to validate TLS against the pinned public key
[discovery] Cluster info signature and contents are valid and TLS certificate validates against pinned roots, will use API Server "192.168.0.8:6443"[discovery] Successfully established connection with API Server "192.168.0.8:6443"
[bootstrap] Detected server version: v1.8.15
[bootstrap] The server supports the Certificates API (certificates.k8s.io/v1beta1)
Node join complete:
* Certificate signing request sent to master and response
  received.
* Kubelet informed of new secure connection details.

Run 'kubectl get nodes' on the master to see this machine join.
[node2 ~]$

Verifying Kubernetes Cluster

Run the below command on master node

[node1 ~]$ kubectl get nodes
NAME      STATUS    ROLES     AGE       VERSION
node1     Ready     master    15m       v1.10.2
node2     Ready     <none>    1m        v1.10.2
[node1 ~]$

Adding Worker Nodes

[node1 ~]$ kubectl get nodes
NAME      STATUS    ROLES     AGE       VERSION
node1     Ready     master    58m       v1.10.2
node2     Ready     <none>    57m       v1.10.2
node3     Ready     <none>    57m       v1.10.2
node4     Ready     <none>    57m       v1.10.2
node5     Ready     <none>    54s       v1.10.2
[node1 ]$ kubectl get po
No resources found.
[node1 ]$ kubectl get svc
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   1h
[node1 ]$

In the next blog series, I will showcase how to build a simple Nginx application on top of 5-Node Kubernetes cluster.

Kubernetes Hands-on Lab #2 – Running Our First Nginx Cluster

Kubernetes Hands-on Lab #3 – Deploy Istio Mesh on K8s Cluster

Test Drive Your First Istio Deployment using Play with Kubernetes Platform

Estimated Reading Time: 3 minutes

If you’re a Developer and have been spending lot of time in developing apps recently, you already understand a whole new set of challenges related to Microservice architecture. Although there has been a shift from bloated monolithic apps to small, focused Microservices to speed up implementation and to improve resiliency but the fact is  developers have to really worry about the challenges in integrating services in distributed systems which includes accountability for service discovery, load balancing, registration, fault tolerance, monitoring, routing, compliance and security.

Let us understand the challenges which Microservice bring to developers and operators in details. Consider a 1st Generation simple Service Mesh scenario. As shown below, Service (A) talks to Service (B). Instead of talking directly, the request gets routed through Nginx. The Nginx finds route in Consul (which is actually a service discovery tool) and automatic retries on HTTP 502’s happen.

 

But with the advent of growing number of microservices architecture, the below listed challenges arises for both developers as well as operation team which are discussed below –

  • How to enable these growing number of microservices to talk to each other?
  • How to enable these growing number of microservices to load-balance?
  • How to enable these growing number of microservices to provide role-based routing?
  • How to implement outgoing traffic on these microservices and test canary deployment?
  • How to manage complexity around these growing pieces of microservices?
  • How can operator implement fine-grained control of traffic behavior with rich-routing rules?
  • How shall one implement Traffic encryption, service-to-service authentication and strong identity assertions?

 

In nutshell, although you could put service discovery and retry logic into application or networking middleware but the fact is service discovery becomes tricky to get right.

Enter Istio’s Service Mesh

“Service Mesh” is one of the hottest buzzword of 2018. As its name suggest, it is a configurable infrastructure layer for a microservices app. It describes the network of microservices that make up applications and the interactions between them. It makes communication between service instances flexible, reliable, and fast. The mesh provides service discovery, load balancing, encryption, authentication and authorization, support for the circuit breaker pattern, and other capabilities.

Istio is a completely open source service mesh that layers transparently onto existing distributed applications. Istio v1.0 got announced last month and is ready for production. It is written completely in Go Language and is actually a platform, including APIs that let it integrate into any logging platform, or telemetry or policy system. This project adds a very tiny overhead to your system. It is being hosted on GitHub. Istio’s diverse feature set lets you successfully, and efficiently, run a distributed microservice architecture, and provides a uniform way to secure, connect, and monitor microservices.

Read the full story at Knowledgehut.