How To Host Tomcat In Kubernetes?

A popular technique for deploying Java-based web applications that can be scaled using containers is to host Apache Tomcat on a Kubernetes server. You can scale and manage containerized apps with the aid of Kubernetes.

What Is Tomcat?

Apache Tomcat server: Apache Tomcat is a web container. It allows the users to run Servlet and JAVA Server Pages that are based on the web applications. It can be used as an HTTP server. The performance of the Tomcat server is not as good as the designated web server. It can be used as a separate product with its internal Web server. It can also be used as mutually with the other Web-servers which include Apache, Microsoft Internet Information Server, and Microsoft Personal Web-server.

Why To Host Tomcat On Kubernetes?

There are various benefits to running Tomcat on Kubernetes when it comes to delivering and maintaining Java-based web applications. The following are some advantages of Tomcat hosting on Kubernetes:

• Container Orchestration
• Scalability
• Resource Management
• Isolation and Encapsulation
• Declarative Configuration

Step-by-Step Guide To Setup Tomcat On Kubernetes Cluster

Step 1: Create Namespace

You have two options for hosting Tomcat: either make your namespace or use the Kubernetes cluster's default namespace. I was in the process of establishing my namespace, which I wanted to use for deploying my application.

Create a namespace using the command

kubectl create namespace <namespace-name>

kubectl create namespace tomcat-ps

Create a namespace using the YAML

apiVersion: v1
kind: Namespace
metadata:
  name: tomcat-ps
  labels:
    team: prod-team

Step 2: Create Tomcat pod

Creating a Tomcat pod in Kubernetes involves defining a YAML configuration file that describes the pod's specifications. Below are the steps and an explanation for creating a simple Tomcat pod:

apiVersion: v1
kind: Pod
metadata:
  name: tomcatapp
  namespace: tomcat-ps
  labels:
    app: tomcatapp
spec:
  containers:
  - name: tomcat
    image: tomcat:latest  # image
    ports:
    - containerPort: 8080

Explanation of the YAML:

• apiVersion: Specifies the Kubernetes API version being used.
• kind: Indicates the type of resource being created, in this case, a Pod.
• metadata: Contains metadata about the Pod, including its name.
• spec: Describes the specification of the Pod.
• containers: Defines the containers running in the Pod.
• name: Specifies the name of the container.
• image: Specifies the Docker image to use for the Tomcat container (in this case, tomcat:latest).
• ports: Specifies the ports to expose on the container.

Step 3: Create NodePort Service for tomcat

To expose the Tomcat pod using a NodePort service in Kubernetes, you'll need to create a service configuration file. Below are the steps to create a NodePort service for the Tomcat pod:

apiVersion: v1
kind: Service
metadata:
  name: tomcatappsvc
  namespace: tomcat-ps
spec:
  type: NodePort
  selector:
    app: tomcatapp
  ports:
  - port: 80
    targetPort: 8080

Kubernetes allows us to mention the service and pod yaml in single file.

Explanation of each section:

• apiVersion: v1: Specifies the Kubernetes API version being used. In this case, it's version 1.
• kind: Service: Indicates the type of resource being created, which is a Service. A Service in Kubernetes provides a way to expose a set of Pods as a network service.
• metadata: Contains metadata about the service, including its name (tomcatappsvc) and the namespace (tomcat-ps) in which it should be created.
• spec: Describes the specification of the service, defining its behavior and how it should route traffic to the associated Pods.
• type: NodePort: Specifies the type of service. In this case, it's a NodePort service. NodePort services make a specific port on each node in the cluster accessible externally. The service will be reachable on a randomly assigned port within a specified range (usually 30000-32767).
• selector: Identifies the Pods that this service will route traffic to. In this example, it selects Pods with the label app: tomcatapp. This label is used to match the service with the corresponding Pods.
• ports: Specifies the ports to expose on the service.
• port: 80: Defines the port on the service itself. In this case, it's port 80, the standard port for HTTP traffic.
• targetPort: 8080: Specifies the port on the Pods to which traffic should be forwarded. In this example, it's port 8080, which is a common port for Tomcat applications.

In summary, this Service configuration (tomcatappsvc) creates a NodePort service in the tomcat-ps namespace. The service will route external traffic on port 80 to the Pods with the label app: tomcatapp on port 8080. Ensure that your Tomcat Pods have the specified label (app: tomcatapp) so that they are correctly associated with this service.

Step 4: List every pod in the namespace you defined by applying the yaml file in Kubernetes.

For that use the following command.

kubectl get all -n <namespace>

Namespace you have created: List all the pods in it.

kubectl get all -n tomcat-ps

The screenshot above shows that the Tomcat pod is now operating on port "32014".

Step 5: Accessthe Tomcat from the internet.

http://IPaddress:<port number>