- Published on
Microservices with Java, Kubernetes, Microk8s, and Kong Gateway with a simple User Management Application
- Authors
- Name
- Gary Huynh
- @gary_atruedev
Alright, my friend, fasten your seatbelt and prepare for an epic adventure through the realms of Java, Kubernetes, microk8s, and Kong Gateway. Together, we'll conquer the world of microservices and user management! Let's dive right in.
๐ Related Learning Paths
Before we start, you might want to check out these foundational topics:
- ๐ Java Security Series - Essential for securing your microservices
- ๐งน Java Clean Code Principles - Write maintainable microservice code
- ๐ Real-time Notifications with Kafka - Add event-driven communication
- ๐ฏ Exception Handling in Spring Boot - Handle errors gracefully
First, let's meet our three trusty services: employee management
, employee promotion
, and employee resignation
. We'll implement them using the powerful Spring Boot
framework.
- Employee Management Service:
@RestController
@RequestMapping("/employees")
public class EmployeeManagementController {
@GetMapping("/{id}")
public ResponseEntity<Employee> getEmployeeById(@PathVariable String id) {
// Logic to fetch employee details from the database
Employee employee = employeeService.getEmployeeById(id);
if (employee == null) {
return ResponseEntity.notFound().build();
}
return ResponseEntity.ok(employee);
}
@PostMapping
public ResponseEntity<Employee> createEmployee(@RequestBody Employee employee) {
// Logic to create a new employee in the database
Employee createdEmployee = employeeService.createEmployee(employee);
return ResponseEntity.status(HttpStatus.CREATED).body(createdEmployee);
}
// Additional methods for updating and deleting employees
}
- Employee Promotion Service:
@RestController
@RequestMapping("/promotions")
public class EmployeePromotionController {
@PostMapping("/{id}")
public ResponseEntity<Employee> promoteEmployee(@PathVariable String id) {
// Logic to promote an employee in the database
Employee promotedEmployee = employeeService.promoteEmployee(id);
if (promotedEmployee == null) {
return ResponseEntity.notFound().build();
}
return ResponseEntity.ok(promotedEmployee);
}
// Additional methods for managing promotions
}
- Employee Resignation Service:
@RestController
@RequestMapping("/resignations")
public class EmployeeResignationController {
@PostMapping("/{id}")
public ResponseEntity<String> handleResignation(@PathVariable String id) {
// Logic to handle employee resignation
// Send resignation notification, update employee status, etc.
return ResponseEntity.ok("Resignation handled successfully");
}
// Additional methods for managing resignations
}
These delightful code snippets demonstrate the implementation of our three services using Spring Boot's magic. Each service has its own controller with carefully crafted endpoints and business logic.
Now, let's move on to the deployment stage. We'll utilize the lightweight microk8s
for our local Kubernetes cluster
. Here's what you need to do:
-
Install
microk8s
: Follow the official microk8s documentation to install and configure it on your machine. -
Create
YAML manifests
for the services: Declare the deployment and service configurations for each service in separate YAML files. Here's an example for the Employee Management Service:
apiVersion: apps/v1
kind: Deployment
metadata:
name: employee-management
spec:
replicas: 1
selector:
matchLabels:
app: employee-management
template:
metadata:
labels:
app: employee-management
spec:
containers:
- name: employee
-management
image: your-employee-management-image:tag
ports:
- containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
name: employee-management
spec:
selector:
app: employee-management
ports:
- protocol: TCP
port: 80
targetPort: 8080
- Apply the YAML files: Use the
kubectl apply -f <filename>
command to apply the YAML files and deploy the services tomicrok8s
. Repeat this step for each service.
kubectl apply -f employee-management.yaml
kubectl apply -f employee-promotion.yaml
kubectl apply -f employee-resignation.yaml
Fantastic! Our microservices
are now happily running in the microk8s cluster
.
But wait, there's more! Let's take our API management
to the next level by integrating Kong Gateway
. Follow these steps:
-
Install
Kong Gateway
: Refer to the Kong Gateway documentation for installation instructions tailored to your environment. -
Declare Kong as the
Ingress Controller
: In yourKubernetes
manifest file (e.g.,kong.yaml
), define Kong as theingress controller
.
apiVersion: apps/v1
kind: Deployment
metadata:
name: kong-proxy
spec:
replicas: 1
selector:
matchLabels:
app: kong-proxy
template:
metadata:
labels:
app: kong-proxy
spec:
containers:
- name: kong-proxy
image: kong:latest
ports:
- containerPort: 8000
- containerPort: 8443
- containerPort: 8001
- containerPort: 8444
- Create
Kong Services and Routes
: Define Kong services and routes for each of our user management services. These configurations tell Konghow to map incoming requests to the corresponding services
.
apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
name: employee-management-plugin
config:
service_id: <employee-management-service-id>
plugin: key-auth
---
apiVersion: configuration.konghq.com/v1
kind: KongIngress
metadata:
name: employee-management-ingress
spec:
rules:
- http:
paths:
- path: /employees
method: GET
backend:
serviceName: employee-management
servicePort: 80
- path: /employees
method: POST
backend:
serviceName: employee-management
servicePort: 80
# Add more paths for other operations
---
# Repeat the above sections for employee-promotion and employee-resignation
- Apply Kong configurations: Deploy the Kong configurations to your microk8s cluster using the
kubectl apply -f <filename>
command.
kubectl apply -f kong.yaml
kubectl apply -f kong-services.yaml
Marvelous! Our services are now integrated with Kong Gateway
, providing advanced API management capabilities.
To access your services through Kong, utilize Kong's proxy URL
. For example, if Kong is exposed at http://localhost:8000
, you can access the employee management service at http://localhost:8000/employees
.
Congratulations, my Java-savvy friend! You've successfully mastered microservices with Java, Kubernetes, microk8s, and Kong Gateway. Now, go forth, explore the endless possibilities of microservice architectures, and may your laughter be as infinite as your coding prowess!
๐ Next Steps & Related Topics
Continue Your Microservices Journey:
- ๐ Implement CDC with Debezium and Kafka - Capture database changes in real-time
- ๐ Add Real-time Notifications - Build event-driven features
- ๐๏ธ System Architecture Best Practices - Learn from Sam Newman's insights
Strengthen Your Foundation:
- ๐ก๏ธ Secure Your Microservices - Implement SSL/TLS
- ๐งช Write Better Tests - API testing strategies
- ๐ง Master CI/CD - Automate your deployments
Level Up Your Skills:
- ๐ง Manage Stress in Complex Projects - Stay healthy while building
- ๐ค Boost Productivity with AI - Modern development tools
- ๐ Java Security Fundamentals - Complete 16-part series
Remember: Microservices are powerful but complex. Take time to understand each component before scaling up!