How to do Persistence based on Cookie Value on F5

In F5 BIG-IP, you can create an iRule to implement universal persistence based on the value of a cookie. Here’s an example iRule that checks the cookie value and sends traffic to the corresponding pool member:

when HTTP_REQUEST {
    # Retrieve the value of the "MyCookie" cookie from the request
    set cookie_value [HTTP::cookie "MyCookie"]
    
    if { $cookie_value eq "1" } {
        # If the cookie value is "1", send traffic to the first pool member
        pool my_pool_1
    } elseif { $cookie_value eq "2" } {
        # If the cookie value is "2", send traffic to the second pool member
        pool my_pool_2
    } else {
        # If the cookie value is neither "1" nor "2", use default pool or take appropriate action
        # pool my_default_pool
        # You can handle other cases here if needed
    }
}

In this iRule, we first retrieve the value of the “MyCookie” cookie from the HTTP request using the HTTP::cookie command. Then, we use conditional statements to check the value of the cookie. If the value is “1,” the traffic is sent to the first pool member (replace my_pool_1 with the actual name of your pool). If the value is “2,” the traffic is sent to the second pool member (replace my_pool_2 with the actual name of your second pool). You can also add additional logic for handling other cases or a default pool as needed.

Make sure to replace “MyCookie” with the actual name of the cookie you want to use for persistence, and replace the pool names with the names of your pools. Additionally, you may need to adjust this iRule to fit your specific configuration and requirements.

1. Access the BIG-IP Configuration Utility: Log in to the Configuration Utility of your F5 BIG-IP device using a web browser. Enter the IP address of your device and appropriate credentials to log in.
2. Navigate to iRules: Once logged in, navigate to the “Local Traffic” menu on the left sidebar. Under “Local Traffic,” select “iRules” to manage iRules.
3. Create a New iRule: Click on “Create” to create a new iRule. Give your iRule a name (e.g., “Universal_Persistence”) and paste the iRule script into the text area.
4. Save the iRule: After pasting the iRule script, click on the “Finished” button to save the iRule.
5. Attach the iRule to a Virtual Server: Now, you need to attach the iRule to a virtual server that handles the traffic you want to apply this rule to. Navigate to “Local Traffic” > “Virtual Servers” and select the appropriate virtual server.
6. Attach the iRule: In the properties of the virtual server, locate the “Resources” section and click on “iRules”. Then, click on “Manage” and select the iRule you created (“Universal_Persistence”). Add it to the list of iRules attached to the virtual server.
7. Save Changes: After attaching the iRule, click on the “Finished” button to save the changes to the virtual server configuration.

Once you’ve completed these steps, the iRule will be applied to the traffic handled by the specified virtual server. It will inspect the cookie value in the HTTP request and route the traffic to the appropriate pool member based on the value of the cookie.