> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Demo Service Definition and Registration > Learn to register, test, and deregister a service in Consul while observing changes in the UI. In this lesson, you’ll learn how to register a service in Consul, watch it appear in the UI, test it without a health check, and finally deregister it. Our environment consists of two Consul servers and one web client node (`web-server-01`). ## Verify Cluster Membership On one of the Consul servers (`consul-node-a`), confirm that all nodes have joined the cluster: ```bash theme={null} [ec2-user@consul-node-a ~]$ consul members Node Address Status Type Build Protocol DC Segment consul-node-a 10.0.101.110:8301 alive server 1.9.3+ent 2 us-east-1 consul-node-b 10.0.101.248:8301 alive server 1.9.3+ent 2 us-east-1 web-server-01 10.0.101.177:8301 alive client 1.9.3+ent 2 us-east-1 ``` Switch to the web client node (`web-server-01`) to define and register your service. You can watch these changes propagate instantly in the Consul UI: ![The image shows a terminal window and a web browser displaying a Consul interface with a list of nodes, including "consul-node-a," "consul-node-b," and "web-server-01."](https://kodekloud.com/kk-media/image/upload/v1752877894/notes-assets/images/HashiCorp-Certified-Consul-Associate-Certification-Demo-Service-Definition-and-Registration/consul-interface-terminal-browser-nodes.jpg) ## Service Definition File On `web-server-01`, create a JSON file to describe your service: ```bash theme={null} [ec2-user@ip-10-0-101-177 ~]$ vi service.json ``` Add the following content: ```json theme={null} { "ID": "web-server-01", "Name": "front-end-eCommerce", "Tags": ["v7.05", "production"], "Address": "10.0.101.177", "Port": 80 } ``` The `service.json` file follows Consul’s service definition schema. You can extend it later with health checks under the `"Check"` block. ### Service Definition Fields | Field | Description | Example | | ------- | --------------------------------- | --------------------- | | ID | Unique identifier for the service | `web-server-01` | | Name | Logical name of the service | `front-end-eCommerce` | | Tags | Metadata labels | `v7.05`, `production` | | Address | Service IP address | `10.0.101.177` | | Port | Listening port | `80` | ## Register the Service Register your service definition with Consul: ```bash theme={null} [ec2-user@ip-10-0-101-177 ~]$ consul services register service.json Registered service: front-end-eCommerce ``` In the Consul UI, the new service appears under **Services** with a healthy status: ![The image shows a web interface for managing services, specifically displaying details for a service named "front-end-eCommerce" with a healthy status for "web-server-01." It includes options for searching and filtering by health status.](https://kodekloud.com/kk-media/image/upload/v1752877895/notes-assets/images/HashiCorp-Certified-Consul-Associate-Certification-Demo-Service-Definition-and-Registration/web-interface-managing-services-frontend-ecommerce.jpg) Meanwhile, Apache is serving its default test page: ![The image shows a default Apache HTTP server test page, indicating the server is installed but not yet configured with content.](https://kodekloud.com/kk-media/image/upload/v1752877896/notes-assets/images/HashiCorp-Certified-Consul-Associate-Certification-Demo-Service-Definition-and-Registration/apache-http-server-test-page.jpg) ## Testing Without a Health Check Stop the Apache HTTP server: ```bash theme={null} [ec2-user@ip-10-0-101-177 ~]$ sudo systemctl stop httpd ``` Reloading the test page in your browser times out, but in Consul, the `front-end-eCommerce` service still shows as `passing` because no application-level health check is defined. Without a defined health check, Consul cannot detect application failures. Always configure checks to get accurate health status! Restore the default page by restarting Apache: ```bash theme={null} [ec2-user@ip-10-0-101-177 ~]$ sudo systemctl start httpd ``` ## Deregister the Service To remove the service from Consul: ```bash theme={null} [ec2-user@ip-10-0-101-177 ~]$ consul services deregister service.json Deregistered service: web-server-01 ``` You can also deregister services via the Consul UI or the HTTP API by specifying the service ID. The `front-end-eCommerce` entry disappears from the Consul UI. ## Links and References * [Consul Service Definition Documentation](https://www.consul.io/docs/agent/services) * [Consul HTTP API: Service Registration](https://www.consul.io/api-docs/agent/service) * [Consul UI Guide](https://www.consul.io/docs/gui)