Dynamic routing with nginx, lua and redis - nginx

Question

I am trying to make nginx perform proxying based on the URI with the help of lua and redis.
So far, I am able to successfully proxy simple URI like '/hello' to desired target. Was able to achieve this by saving the mappings in a redis hashmap something like,
HGETALL "127.0.0.1:8080"
1) "/demo1/test/hello4"
2) "example.com/demo1/test/hello4"
3) "/hello"
4) "example.com/hello"
nginx.conf
worker_processes 2;
error_log logs/error.log info;
events {
worker_connections 1024;
}
http {
server {
listen 8080;
location / {
resolver 8.8.4.4; # use Google's open DNS server
set $target '';
access_by_lua '
local http_host = ngx.var.http_host
if not http_host then
ngx.log(ngx.ERR, "no http-host found")
return ngx.exit(400)
end
local redis = require "resty.redis"
local red = redis:new()
red:set_timeout(1000) -- 1 second
local ok, err = red:connect("127.0.0.1", 6379)
if not ok then
ngx.log(ngx.ERR, "failed to connect to redis: ", err)
return ngx.exit(500)
end
local fPath, err = red:hget(http_host, ngx.var.uri)
if not fPath then
ngx.log(ngx.ERR, "No fPath: ", err)
return ngx.exit(500)
end
ngx.var.target = fPath
';
proxy_pass $target;
}
}
}
However, I also want to handle dynamic URI's like example:-
user/id/1 -> "example.com/user/id/1",
user/id/2 -> "example.com/user/id/2",
user/id/3 -> "example.com/user/id/3",
and so on....
I am not sure how can I create a key value pair in redis and lua logic for this case which can handle the dynamicity of the id's.
I tried looking but haven't been able to find the right direction or some resource to aid me in figuring this out.
Any help would be really great!

Answer 1

If you want to achieve this in production, I would recommend using mature API gateways like Apache APISIX or Kong. To implement it yourself, maybe you could store paths with wildcard or Lua patterns in Redis to allow later matching to the original URI. Applying some simple heuristics would help reduce the range of checking.