How to set different http header for different upstream backend?

876766806 · 2020-02-18T13:37:00+00:00

Dear all, Is there a way to catch an expired client certificate instead of having to return an error page?I configured nginx such that the client certif...

How to set different http header for different upstream backend?

876766806

hey friends:

I have some problems in using balance_by_lua module. Here is my code :

-----------------------------------------------------------------------------------------------

proxy_next_upstream error timeout invalid_header non_idempotent http_502 http_504;

proxy_next_upstream_tries 4;

upstream backend {

server 0.0.0.1;

balancer_by_lua_block {

local balancer = require "ngx.balancer"

local host, port = select_backend()

balancer.set_current_peer(host, port)

}

-----------------------------------------------------------------------------------------------

when the upstream status is 502 or 504, I can select a new backend. Now, I want to set different http header for different upstream backend. But we know that ngx.req.set_header function can not be used in balancer_by_lua* status. So, does anyone has some good idea to solve this problem?

piotrprz

It's a bit convoluted but it can be done. The general idea is to use error_page handler to change headers and redirect nginx back to location with balancer_by_lua.

nginx builds upstream request only once, so each retry must be treated as a new request - and this workaround achieves that. I tested this some time ago on 1.13.

W dniu wtorek, 18 lutego 2020 06:37:02 UTC+1 użytkownik Atwood Huang napisał:

hey friends:
I have some problems in using balance_by_lua module. Here is my code :
-----------------------------------------------------------------------------------------------
proxy_next_upstream error timeout invalid_header non_idempotent http_502 http_504;
proxy_next_upstream_tries 4;
upstream backend {
server 0.0.0.1;
balancer_by_lua_block {
local balancer = require "ngx.balancer"
local host, port = select_backend()
balancer.set_current_peer(host, port)
}
-----------------------------------------------------------------------------------------------

when the upstream status is 502 or 504, I can select a new backend. Now, I want to set different http header for different upstream backend. But we know that ngx.req.set_header function can not be used in balancer_by_lua* status. So, does anyone has some good idea to solve this problem?

atwoodhuang94

thanks, I think it is a good idea, I will try it!

在 2020年2月22日星期六 UTC+8上午8:47:40，Piotr Przybylski写道：

It's a bit convoluted but it can be done. The general idea is to use error_page handler to change headers and redirect nginx back to location with balancer_by_lua.

nginx builds upstream request only once, so each retry must be treated as a new request - and this workaround achieves that. I tested this some time ago on 1.13.

W dniu wtorek, 18 lutego 2020 06:37:02 UTC+1 użytkownik Atwood Huang napisał:
hey friends:
I have some problems in using balance_by_lua module. Here is my code :
-----------------------------------------------------------------------------------------------
proxy_next_upstream error timeout invalid_header non_idempotent http_502 http_504;
proxy_next_upstream_tries 4;
upstream backend {
server 0.0.0.1;
balancer_by_lua_block {
local balancer = require "ngx.balancer"
local host, port = select_backend()
balancer.set_current_peer(host, port)
}
-----------------------------------------------------------------------------------------------

when the upstream status is 502 or 504, I can select a new backend. Now, I want to set different http header for different upstream backend. But we know that ngx.req.set_header function can not be used in balancer_by_lua* status. So, does anyone has some good idea to solve this problem?