Nginx rewrite/return phase order

Question

I know there are Nginx phases. Why does the following snippet deliver the "200 Host: example.com" instead of forwarding to Google? What would be a generally valid workaround to evaluate Lua higher or before?

server { listen 80; server_name example.com; location / { rewrite_by_lua_block { return ngx.redirect('https://www.google.com/', 303) } default_type text/plain; return 200 "Host: $host"; } } 

Maybe this doesn't make sense at first sight, but I have an intelligent way to block/redirect certain calls in the Lua block (or in a Lua file included at this point). This module should work in general. With proxy_pass, alias etc. it works fine. Only with return 200 it does not work. Does anyone have an idea?

Answer 1

https://github.com/openresty/lua-nginx-module#rewrite_by_lua

Note that this handler always runs after the standard ngx_http_rewrite_module.

So return 200 always executes before rewrite_by_lua_block.

In your case you should stick to rewrite_by_lua_block (didn't check)

if condition then return ngx.redirect('https://www.google.com/', 303) else ngx.print("Hello"); return ngx.exit(ngx.HTTP_OK) end 

Answer 2

Credits to Alexey Ten.

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As an intermediate conclusion (until proven otherwise), instead of using Nginx code directly, I must implement return 200 in Lua.

 rewrite_by_lua_block { -- Will be executed. Can of course be combined with a condition. return ngx.redirect('https://www.google.com/', 303) } content_by_lua_block { ngx.header["Content-Type"] = "text/plain" ngx.print("Host: "..ngx.var.host) return ngx.exit(ngx.HTTP_OK) } 

This is not what I want, but I had asked for a workaround. If anyone has a better one, go ahead.