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Traffic flow:
Client -> FortiADC Virtual Server -> Real Server Pool -> Server1 / Server2.
Virtual Server FQDN: dvwa.ftntlab.local.
Server1: 10.100.1.209.
Server: 10.100.1.43.
Requirement:
When the request matches the specified domain name, add the response HTTP header 'X-Backend-Server' with the real server identifier.
- Create a Server Load Balance script:
Server Load Balance -> Scripting -> Create New.
a. Define a name.
b. Input Lua script statement.
local shared_host
when HTTP_REQUEST {
host = HTTP:header_get_value("Host");
if host == "<domain-name>" then
shared_host = host
else
end
}
when HTTP_RESPONSE {
if shared_host then
sip = HTTP:server_addr()
debug("backend server IP is %s\n", sip);
local backend_servers = {
["<serverIP-1"] = 1,
["<serverIP-2"] = 2,
}
if backend_servers[sip] then
local server_identifier = backend_servers[sip]
HTTP:header_insert("X-Backend-Server", tostring(server_identifier))
log("Server IP is: " .. sip .. ", Server identifier is: " .. server_identifier)
end
end
}
Details and comments on the Lua script are used in this article.
Note that there is a static record for variable backend_servers that needs to be maintained if the server IP address is changed.
-
Assign Server Load Balance script to Virtual Server.
Note that the round-robin load-balancing method was used for this demonstration.
Demonstration:
• Send request using HTTPie.
• Verify “X-Backend-Server” in response HTTP header.
First request:
Second request:
In the FortiADC script log, there will be a log generated if the script is triggered: Log & Report -> Script Log.
Note: Refer to the article for more information: How to Generate script log.
Related documentation on Server Load Balance script usage:
Using HTTP scripting
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