Quick Start for CLB

CLB supports TCP/UDP/HTTP/HTTPS protocols and provides flexible forwarding capabilities based on domain names and URL paths. This document describes how to quickly use IPv4 CLB.

Prerequisites

1. CLB is only responsible for forwarding traffic and does not have the ability to process requests. Therefore, you need to have CVM instances that handle user requests.
   In this example, only two CVM instances are required. You can also plan the number of CVMs yourself. In this example, CVM instances rs-1 and rs-2 has been created in the NCR region.
2. In this document, HTTP forwarding is used for example to illustrate that the corresponding Web server, such as Apache, Nginx, IIS, etc, must be deployed on the CVM.
   In the example, Apache is deployed on rs-1 to return an HTML page with Hello Tomcat! This is rs-1! and deployed on rs-2 to return an HTML page with Hello Tomcat! This is rs-2! in order to verify the results. For more information about CVM deployment, see Deployment of Java Web on Linux (CentOS) and Installment and Configuration of PHP on Windows.
3. Access the public network IP + path of the CVM. If the displayed result is the page you deployed, it means that the service has been deployed successfully.

   Note:

   In this example, the service return values deployed by the backend server are different and are only used for feature verification. In practice, to ensure that all users have a consistent experience, exactly the same services are usually deployed on the backend servers.

Create a CLB instance

1. log in to Converge Cloud CLB .
2. Select a region, click Create, and then enter the Cloud Load Balancer LB window.
3. Configure the CLB instance parameters. The configuration example in this document is shown in the figure. Configure according to the actual situation.

4. Click Confirm Activation. After the instance is successfully created, you can see the newly created instance in the list.

Create a CLB listener

The Load Balance Listener is responsible for the actual forwarding by specifying the protocol and port. In this document, the configuration of CLB forwarding the client's HTTP request is used as an example.

Configure HTTP listening protocol and port

1. Log in to the cloud console, click Cloud Products > Cloud Computing & Networking > Cloud Load Balancer to open the CLB console.
2. In the LB Instance List, find the created CLB instance clb-test and click the instance ID to open the CLB details page.
3. In the Basic Info module, you can click the edit icon after the name to modify the instance name.
4. In Listener Management, click Create under HTTP/HTTPS Listener to create a new Load Balance Listener.
   
5. In the dialog box that pops up, configure the following parameters, and click [Confirm] when done.

Configuring the forwarding rules for the listener

1. In "Listener Management", select the newly created listener Listener1, click +, and start adding rules.
   
2. In the forwarding rule dialog box that pops up, set basic configuration information such as domain name, URL path, and balancing method, and click next step: Health Check.
   • Domain name: the domain name used by your backend service. In this example, www.qcloudtest.com is used. Domain name supports wildcards. For details, see Configuration Instructions.
   • URL Path: the access path of your backend service. In this example, /image/ is used.
   • Select Polling by Weight for the balance mode.
     
3. Configuring health check: Enable health check, check whether the domain name uses default forwarding domain name and forwarding path, and click next step: Session Affinity.
   

4. Session Affinity: Enable session affinity, set the persistence time, and click Submit to complete the configuration of the listener forwarding rule.

   For more information about Load Balance Listener, see Load Balance Listener Overview.

   Note:

   • One listener (i.e. listening protocol: port) can be configured with multiple domain names, and one domain name can be configured with multiple URL paths. Select the listener or domain names and click the + sign to create a new rule.

• Session persistence: If the user disables session persistence and select round-robin scheduling, requests will be allocated to different backend servers in turn. If the user enables session persistence, or disables session persistence and selects IP Hash scheduling, requests will be continuously allocated to the same backend server.
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Binding Cloud Virtual Machine (CVM)

1. On the Listener Management page, select the triangle icon next to the newly created listener to expand Listener1. Select and expand the domain name and URL path in turn. The information of CVM bound to the URL path is displayed on the right side of the screen. Click Bind.
   

2. In the pop-up box, select the CVM instances rs-1 and rs-2 in the same region as the CLB. Set the CVM ports to 80 and the CVM weights to the default value 10.
   

3. Click OK to complete binding.

4. Expand the listener to the URL path dimensionality to view the bound CVM and its health check status. When the status is healthy, it means that the CVM can normally process the requests forwarded by the CLB.
   

   Note:

   One forwarding rule (listening protocol + port + domain name + URL path) can bind multiple ports of the same CVM. If the user deploys the same service in ports 80 and 81 of rs-1, the CLB supports the forwarding rules in the example binds ports 80 and 81 of rs-1 at the same time, and both ports will receive the request forwarded by CLB.

Verifying the CLB Service

After you configure CLB, you can verify whether the architecture is effective, that is, verify different backend CVMs are accessed through different domain names + URLs under a CLB instance, or, verify content-based routing feature.

Method 1: Configuring hosts to point the domain name to CLB

1. On a Windows system, go to the directory C:\Windows\System32\drivers\etc, modify the hosts file, and map the domain name to the VIP of the CLB instance.
   
2. To verify whether the hosts are configured successfully, you can run cmd and use the ping command to check whether the domain name is successfully bound to the VIP. If there is a data packet, the binding is successful.
3. Enter the access path http://www.qcloudtest.com/image/ in the browser to test the CLB service. As shown in the following figure, the request has been forwarded by CLB to the CVM rs-1, and the CVM processed and returned the request normally.
   
4. The round-robin scheduling algorithm of this listener is Weighted Round Robin, and the weights of the two CVMs are both 10. Refresh the browser and send the request again. You can see that this request has been forwarded by CLB to the CVM rs-2.
   

   Note:

   The / in image/ must be retained. It indicates that image is the default directory, not a file name.

Method 2: Configuring DNS to point the domain name to CLB

1. Log in to the cloud console and click Cloud Products > Domain Name Services > VPCDNS.
2. Click the Domain Name you purchased, click the Add Record button on the Domain DNS Management page, add an A record for the domain, and enter the following content:
   • Record type: A record.
   • Host record: This is the domain name prefix. In this example, to resolve all prefixes, set it to *.qcloudtest.com.
   • Record value: Enter the CLB IP address here.
   • Weight: Set this to its default value 100.
3. After addition, click OK.
   It takes some time for DNS to propagate the record across the Internet. To test whether the domain name is resolved normally, you can directly access the bound CNAME domain name (such as www.qcloudtest.com in this example) after the DNS record for a period of time to verify CLB.