Adding an HTTP Listener

Scenarios

You can add an HTTP listener if content identification is required. HTTP is a great fit for workloads such as web applications and mobile mini-games.

Notes and Constraints

• If the listener protocol is HTTP, the backend protocol is HTTP by default and cannot be changed.
• If you only select network load balancing (TCP/UDP) for your dedicated load balancer, you cannot add an HTTP listener to this load balancer.

Procedure

1. Go to the load balancer list page.
2. On the displayed page, locate the load balancer and click its name.
3. Under Listeners, click Add Listener. Configure the parameters based on Table 1.

   Table 1 Parameters for configuring an HTTP listener

   Parameter	Description
   Name	Specifies the listener name.
   Frontend Protocol	Specifies the protocol that will be used by the load balancer to receive requests from clients. Select HTTP.
   Frontend Port	Specifies the port that will be used by the load balancer to receive requests from clients. The port number ranges from 1 to 65535.
   Redirect	Specifies whether to enable redirection. If you have both HTTPS and HTTP listeners, you can use this function to redirect the requests from an HTTP listener to an HTTPS listener to ensure security. After the redirection is added for an HTTP listener, the backend server will return 301 Moved Permanently to the clients.
   Redirected To	Specifies the HTTPS listener to which requests are redirected if Redirect is enabled.
   Access Control	Specifies how access to the listener is controlled. For details, see What Is Access Control? The following options are available: All IP addresses Blacklist Whitelist
   IP Address Group	Specifies the IP address group associated with a whitelist or blacklist. If there is no IP address group, create one first. For more information, see IP Address Group.
   Transfer Client IP Address	Specifies whether to transmit IP addresses of the clients to backend servers. This function is enabled for dedicated load balancers by default and cannot be disabled.
   Advanced Forwarding	Specifies whether to enable the advanced forwarding policy. You can add advanced forwarding policies to HTTP or HTTPS listeners to forward requests to different backend server groups. For more information, see Advanced Forwarding.
   Advanced Settings
   HTTP Headers	You can enable the following options as needed. Transfer headers: Transfer Load Balancer EIP: transmits the EIP bound to the load balancer to backend servers through the X-Forwarded-ELB-IP header. Transfer Listener Port Number: transmits the port number used by the listener to backend servers through the X-Forwarded-Port header. Transfer Port Number in the Request: transmits the port number used by the client to backend servers through the X-Forwarded-For-Port header. Transfer Load Balancer ID: transmits the load balancer ID to backend servers through the X-Forwarded-ELB-ID header. Rewrite headers: Rewrite X-Forwarded-Host: rewrites the Host header of the client into the X-Forwarded-Host header and transmits it to the backend servers. Rewrite X-Forwarded-Proto: rewrites the listener protocol into the X-Forwarded-Proto header and transmits it to the backend servers. Rewrite X-Real-IP: rewrites the source IP address of the client into the X-Real-IP header and transmits it to the backend servers. For details, see HTTP Headers. NOTE: More HTTP headers are coming soon. See the available HTTP headers on the management console.
   Data Compression	Specifies whether to enable the data compression option. If you do not enable this option, files will not be compressed. Brotli can compress all files. Gzip can be configured to compress the following content types: text/xml text/plain text/css application/javascript application/x-javascript application/rss+xml application/atom+xml application/xml application/json. NOTE: This option is available in certain regions. You can see which regions support this option on the console.
   Idle Timeout (s)	Specifies the length of time for a connection to keep alive, in seconds. If no request is received within this period, the load balancer closes the connection and establishes a new one with the client when the next request arrives. The idle timeout duration ranges from 0 to 4000.
   Request Timeout (s)	Specifies the length of time (in seconds) that a load balancer is willing to wait for a client request to complete. The load balancer terminates the connection if a request takes too long to complete. The request timeout duration ranges from 1 to 300.
   Response Timeout (s)	Specifies the length of time (in seconds) after which the load balancer sends a 504 Gateway Timeout error to the client if the load balancer receives no response from the backend server after routing a request to the backend server and receives no response after attempting to route the same request to other backend servers. The response timeout duration ranges from 1 to 300. NOTE: If you have enabled sticky sessions and the backend server does not respond within the response timeout duration, the load balancer returns 504 Gateway Timeout to the clients.
   Maximum New Connections per AZ	Specifies the maximum number of new connections that a listener can handle per second in each AZ. The value ranges from 0 to 1000000. 0 indicates that the number is not limited. If the value is greater than the number defined in the load balancer specifications, the latter is used as the limit. NOTE: This option is available in certain regions. You can see which regions support this option on the console.
   Maximum Concurrent Connections per AZ	Specifies the maximum number of concurrent connections that a listener can handle per second in each AZ. The value ranges from 0 to 1000000. 0 indicates that the number is not limited. If the value is greater than the number defined in the load balancer specifications, the latter is used as the limit. Reducing the concurrent connection limit do not interrupt established connections. NOTE: This option is available in certain regions. You can see which regions support this option on the console.
   Tag	Adds tags to the listener. Each tag is a key-value pair, and the tag key is unique. NOTE: This option is available in certain regions. You can see which regions support this option on the console.
   Description	Provides supplementary information about the listener. You can enter a maximum of 255 characters.

4. Click Next: Configure Request Routing Policy.
   1. You are advised to select an existing backend server group.
   2. You can also click Create new to create a backend server group.
      1. Configure the backend server group based on Table 3.
      2. Click Next: Add Backend Server. Add backend servers and configure health check for the backend server group.

         For details about how to add backend servers, see Backend Server Overview. For the parameters required for configuring a health check, see Table 4.

5. Click Next: Confirm.
6. Confirm the configurations and click Submit.