Forwarding Policy (Shared Load Balancers)

Scenarios

You can add forwarding policies to HTTP or HTTPS listeners to forward requests to different backend server groups based on domain names or URLs.

This is suited for applications that are deployed on multiple backend servers and provide multiple types of services such as videos, images, audios, and texts.

A forwarding policy consists of a forwarding rule and an action.

• There are two types of forwarding rules: domain name and URL.
• The only supported action is to forward requests to a backend server group.

Constraints and Limitations

• Forwarding policies can be added only to HTTP and HTTPS listeners.
• When you add a forwarding policy, note the following:
  • Each URL path must exist on the backend server. If the path does not exist, the backend server will return 404 Not Found.
  • A URL path cannot be configured for two forwarding policies.
  • In the regular expression match, the characters are matched sequentially, and matching ends when any rule is successfully matched. Matching rules cannot overlap with each other.
• After you add a forwarding policy, the load balancer forwards requests based on the specified domain name or URL:
  • If the domain name or URL in a request matches that specified in the forwarding policy, the request is forwarded to the backend server group you select or create when you add the forwarding policy.
  • If the domain name or URL in a request does not match that specified in the forwarding policy, the request is forwarded to the default backend server group of the listener.

If you add a forwarding policy that is the same as an existing one, there will be a conflict. Even if you delete the existing forwarding policy, the newly-added forwarding policy is still in the Faulty state. Delete the newly-added forwarding policy and add a different one.

Adding a Forwarding Policy

1. Log in to the management console.
2. In the upper left corner of the page, click and select the desired region and project.
3. Hover on in the upper left corner to display Service List and choose Network > Elastic Load Balancing.
4. Locate the load balancer and click its name.
5. Click Listeners, locate the listener, and click its name.
6. Click Add on the right of Forwarding Policies.
7. In the Add Forwarding Policy dialog box, configure the parameters based on Table 1.
8. Click OK.

   Alternatively, locate the load balancer in the load balancer list and click the name of the listener in the Listener column. In the Listeners area, click Add on the right of Forwarding Policies and then add a forwarding policy.

URL Matching Example

The following table lists how a URL is matched, and Figure 1 shows how a request is forwarded to a backend server group.

Modifying a Forwarding Policy

1. Log in to the management console.
2. In the upper left corner of the page, click and select the desired region and project.
3. Hover on in the upper left corner to display Service List and choose Network > Elastic Load Balancing.
4. Locate the load balancer and click its name.
5. Click Listeners, locate the listener, and click its name.
6. Click Forwarding Policies.
7. Locate the forwarding policy and click on the right of its name.
8. In the Modify Forwarding Policy dialog box, modify the parameters and click OK.

Deleting a Forwarding Policy

1. Log in to the management console.
2. In the upper left corner of the page, click and select the desired region and project.
3. Hover on in the upper left corner to display Service List and choose Network > Elastic Load Balancing.
4. Locate the load balancer and click its name.
5. Click Listeners, locate the listener, and click its name.
6. Click Forwarding Policies.
7. Locate the forwarding policy and click on the right of its name.
8. Click Yes.