A Guide to Using Kubernetes for Microservices

Kubernetes is a powerful open-source container orchestration platform that helps automate the deployment, scaling, and management of containerized applications. It simplifies the process of deploying and running distributed applications at scale, making it an ideal tool for managing microservices. In fact, Kubernetes has become popular in recent years among organizations looking to build and deploy microservices due to its powerful features and active community. Combining Kubernetes with microservices can be a great way to leverage the power of both technologies for maximum efficiency and scalability.

In this guide, we'll go over the basics of using Kubernetes to build and deploy microservices. We'll cover setting up a Kubernetes cluster and creating and deploying a microservice. We'll also learn how to scale and load balance microservices, as well as how to monitor and perform logging in microservices. Finally, we’ll look at some best practices when it comes to deploying microservices on Kubernetes so you can get the most out of your setup.

Let's start by recapping the basics.

What Are Containers and Microservices?

A container is a lightweight, standalone, executable package that includes everything an application needs to run, including the code, runtime, system tools, libraries, and settings. It allows you to easily deploy and scale applications. Additionally, containers provide a consistent and isolated environment for applications to run, regardless of the underlying infrastructure.

Microservices is an architectural style that has revolutionized software development, allowing us to break down complex problems into smaller and more manageable chunks. This method consists of several independent services communicating through APIs, which creates a highly efficient application architecture.

In practice, microservices are often deployed in containers. This is because containers provide the isolation and consistency needed for microservices to run independently and communicate with one another. However, containerization isn't the only way to implement microservices. We can also deploy microservices on virtual machines or bare metal servers.

To sum up, containers are a way to package and distribute software, whereas microservices are an architectural pattern for building software applications. If you want to use containers to deploy and manage microservices, Kubernetes is a popular choice. Let's learn why in the next section.

Benefits of Using Kubernetes for Microservices

Kubernetes is the perfect tool to facilitate and govern microservices thanks to its ability to seamlessly deploy and manage containerized applications. Here are some benefits of using Kubernetes for microservices:

With the many benefits of this technique, it's no surprise why more developers are choosing to implement microservices with Kubernetes! To find out how you can do the same, read on.

Setting up a Kubernetes Cluster

Before you can deploy your microservices, you need to set up a Kubernetes cluster. A cluster is a group of nodes that run the Kubernetes control plane and the container runtime. There are many ways to set up a cluster, including

You can use the Kubernetes command line interface (CLI) to manage your cluster. The Kubernetes CLI, also known as kubectl, is a powerful tool for managing Kubernetes clusters. You can use it to deploy and manage applications on the cluster, inspect its state, and debug any issues that may arise. In order to use kubectl, you must first install it on your computer. You can find instructions to install kubectl here.

Once you've installed kubectl, you should be able to access the CLI by simply typing kubectl in your terminal. You can also check that it has been successfully installed by running the following command:

kubectl version --short

This should return the version of the Kubernetes CLI currently installed on your machine (as shown in the screenshot below).

Once you've completed the installation, there are a few basic commands that you should be familiar with. To view your current clusters and nodes, use the following command:

kubectl get nodes

This will list out all of the nodes in your cluster and their status. To view more detailed information about a node, use the following command:

kubectl describe node <node_name>

This will provide you with more detail, such as the IP address and hostname of the node.

You can also use kubectl to deploy applications on your cluster. To do this, you'll need to create a configuration file for your application. This configuration file should include details such as the number of replicas and the image to use for the pods.

Creating and Deploying a Microservice

Next, you'll need to create a project in Node.js by running the following command:

npm init -y

You'll also need to install the Express package to create a very simple microservice. To do this, run the following command:

npm install express --save

Below is some sample code for a simple microservice in Node.js.

// index.js
const express = require('express');
const app = express();

app.get('/', (req, res) => {
   res.send('Hello World!');
});

app.listen(3000, () => { console.log('Example app listening on port 3000!') });

The basic building block of a Kubernetes deployment is a pod, which is a group of one or more containers that run on a single node. To deploy the above microservice, you create a pod and a deployment, which is a higher-level resource that manages the life cycle of the pod.

To create a pod, you need to create a pod definition in a file called a pod manifest. The pod manifest is a YAML file that specifies the container image, ports, and environment variables for the pod. Here's an example of a pod manifest for the above microservice:

apiVersion: v1
kind: Pod
metadata:
  name: my-web-service
spec:
  containers:
     - name: my-web-service
       image: node:10-alpine
       ports:
         - containerPort: 8080

Once you've created the pod manifest, you can use kubectl to create the pod on the cluster:

kubectl apply -f my-web-service.yaml

After the pod is created, you can use the following command to check the status of the pod:

kubectl get pods

Finally, use the following command to see the logs:

kubectl logs my-web-service

Once you have a pod running, you can create a deployment to manage the life cycle of the pod. A deployment ensures that the desired number of replicas of the pod are running at all times and provides features like rolling updates and rollbacks.

Scaling and Load Balancing Kubernetes Microservices

One of the benefits of using Kubernetes for microservices is the ability to easily scale and load balance your services. To scale a deployment, you can use the following command increase or decrease the number of replicas:

kubectl scale deployment my-web-service --replicas=<no. of replicas>

Service discovery is an important aspect of microservices architecture. It allows microservices to discover and communicate with each other. Kubernetes provides built-in service discovery through its service object, which allows microservices to discover each other by name.

The 12-Factor Methodology

The Twelve-Factor App methodology is a set of guidelines for designing and developing cloud-friendly applications and services. This methodology helps to ensure that services are built in a cloud-friendly way, which can lead to improved performance, scalability, and resilience. When building microservices on Kubernetes, it's important to keep these principles in mind.

1. Codebase: You should always track the microservice code in a version control system, such as Git, and deploy it from there. This makes it easy to roll back changes if necessary and maintain a history of your codebase.
2. Dependencies: You should have a manifest, such as a package.json or POM file, for declaring all dependencies, such as libraries and frameworks, so that you can easily install and update them.
3. Config: You should store configuration in the environment rather than in the code. That way, you can easily change it without changing the code itself.
4. Backing services: Any resources that the twelve-factor microservice uses, such as databases or message queues, should be treated as attached resources. This means that you can easily detach and replace them without affecting the running code.
5. Build, release, run: You should build the microservice using a repeatable and automated build process so that you can release it at any time. Once built, the microservice is deployed into an execution environment, such as a container, and run there.
6. Processes: The twelve-factor application is divided into small, self-contained processes that can be easily started, stopped, and restarted as needed. This makes it easy to scale the application up or down as needed.
7. Port binding: You should design the microservice to run on a certain port so that you can access it easily. This makes it easy to run multiple instances of the app on the same server.
8. Concurrency: You should design the microservice to run concurrently so that it can take advantage of modern computing resources. This means that different parts of the app can be run at the same time on different cores or machines.
9. Disposability: You should design the microservice so you can quickly start or stop it. This makes it easy to deploy new versions or roll back changes if necessary.
10. Dev/prod parity: The twelve-factor microservices have the same environment in development as in production. This makes it easier to catch errors early and avoid surprises when deploying to production.
11. Logs: The twelve-factor microservices treat logs as event streams. This makes it easy to aggregate and process them for monitoring and analysis.
12. Admin processes: The twelve-factor microservices have a separate process for running administrative tasks, such as database migrations. This keeps the app itself clean and focused on its core functionality.

Kubernetes supports the Twelve-Factor App methodology by allowing for automatic scaling and load balancing of microservices, providing built-in service discovery, and allowing for easy configuration management.

Additionally, Kubernetes enables a robust and graceful shutdown of microservices, allowing for quick start-up and maximum robustness. It also allows microservices to be exposed via port binding, making them accessible to other processes, and scaling them out via the process model.

Conclusion to Using Kubernetes for Microservices

Kubernetes is a powerful tool for deploying and managing microservices. By using Kubernetes, you can easily scale and load balance your microservices, implement service discovery, and ensure that your microservices adhere to the principles of the Twelve-Factor App. Kubernetes also provides a platform-agnostic way to manage containerized applications. This makes it easy to deploy and scale applications across different environments. With this guide, you should have a good understanding of how to structure and deploy microservices on Kubernetes, and how to take advantage of its powerful features to build a robust and scalable microservices architecture.

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This post was written by Tarun Telang. Tarun is a software engineering leader with over 16 years of experience in the software industry with some of the world’s most renowned software development firms like Microsoft, Oracle, BlackBerry, and SAP. His areas of expertise include Java, web, mobile, and cloud. He’s also experienced in managing software projects using Agile and Test Driven Development methodologies.