Hi,
You can’t use socket in sample-fetches for HAProxy internal reason.
If you want to take decision using socket+redis, you must set your
Redis request in “action”. according with the redis response, your
action set the result in shared context, and a sample fetche can
return the result. Something like that:
http-request lua.do_my_redis_stuff
use_backend bck_a if { lua.get_redis_result bck_a }
use_backend bck_b if { lua.get_redis_result bck_b }
core.register_action(“do_my_redis_stuff”, fucntion (txn)
-- perform redis request
network = core.tcp()
...
-- get response
response = network:read()
-- store in context
ctx = {}
ctx[‘message’] = response
txn:set_ctx(ctx)
end)
core.register_fetches("get_redis_result", function(txn)
a = txn:get_ctx()
return a[‘message']
end)
Thierry
> On 7 Nov 2019, at 11:56, Kalantari <[email protected]> wrote:
>
>
>
>
> Hi Thierry,
>
> I know this an old thread but I'm having a similar issue where HA Proxy
> doesn't allow me to use Redis (not allowed to use socket in fetches). My
> scenario is as below:
>
> one frontend and multiple backends (proxies). (the frontend is just one IP
> and always sends requests to the same url)
> I use Lua script SmartRouting to:
> A. Look at the body of the body of the message and decide which back end to
> use
> B. If the backend servers being used are too busy (active sessions >
> threshold) then it will choose to send the requests to the offlineAgent
>
> frontend http-in
> bind *:80
> use_backend %[lua.SmartRouting(txn)]
> default_backend OnlineChargers
>
> backend Onlineagent
> server testServer1 ${Server_1_IP}:${Server_1_Port} check
> backend ServersForRequestTypeX
> server testServer1 ${Server_2_IP}:${Server_2_Port} check
> backend offlineAgents
> server testServer1 ${Server_3_IP}:${Server_3_Port} check
> http-response lua.add_DegradedSession
>
> Straight forward up to this point and no need for Redis, however if a message
> is sent to offlineAgent proxy, then I want all the rest of the requests to be
> sent to the offline agent. (each message can have a sessionID
> inside the payload). I tried to add the sessionID for the messages inside my
> SmartRouting to Redis as it was explained in your blogpost but HAProxy throws
> an error and doesn't allow use of a socket in sample fetch.
> below is my Lua script:
>
> -- if number of active sessions goes higher than below then degraded mode is
> detected
> DEGRADED_THRESHOLD = 10
> -- global object which will be used for routing of requests based on request
> type xml tag
> -- if the request type is not found then HA proxy's default backend will be
> used
> routingTable = {
> ["</AccountingReq>"] = "Onlineagent",
> ["</TestReq>"] = "ServersForRequestTypeX"
> }
>
> local function SmartRouting(txn)
> --print_r(txn)
> local payload = txn.sf:req_body()
> -- extract request tag (final occurence of </)
> local requestTag = string.match(payload, "</[^</]*$")
> local selectedBackend = routingTable[requestTag]
> -- check if there's enough capacity (degraded mode)
> -- this check is only neccessary if the
> if (selectedBackend == "Onlineagent") then
> local sessionCount = getTotalSessions()
> if (sessionCount > DEGRADED_THRESHOLD) then
> core.Debug("shit is hiting the fan! Sending requests to degraded
> agent")
> --TODO: Add the sessionID to Redis and check for future requests
> if it's in Redis then redirect to Offline Agent
> return "offlineAgents"
> end
> end
> return selectedBackend
> end
>
> function getTotalSessions()
> local total_sessions = 0
> for _, backend in pairs(core.backends) do
> if backend.name == "Onlineagent" then
> for _, server in pairs(backend.servers) do
> -- Get server's stats
> local stats = server:get_stats()
>
> -- Get the backend's total number of current sessions
> if stats["status"] == "UP" then
> total_sessions = total_sessions + stats["scur"]
> end
> end
> end
> end
> return total_sessions
> end
>
> -- register HAProxy "fetch"
> core.register_fetches("SmartRouting", dreSmartRouting)
