Nginx – Set Nginx Upstream Using Header

nginxreverse-proxy

I've got an Nginx reverse proxy sitting in front of a cluster of microservices. When a new client connects I'd ideally like to use whatever upstream has the least number of connections. They'll receive a token in the response body that they'll pass in the header for all subsequent requests.

I would like the same upstream server to handle all future requests related to that token.

Using "ip_hash" won't work because I need to load balance requests from the same origin IP. (But w/ different header tokens) I can't hardcode a "map" because the microservices are transient. Each request already has to pass through an "auth_request" that is capable of exposing a variable with the proper upstream IP to connect to but I'm not sure how to proxy pass to a dynamic variable.

I'm already using Redis and Memcached for a number of other tasks and I could easily load a "key = header token", "value = upstream IP" into either. But once again I'm not sure how to use a cache value as a proxy upstream target. Most of the cache based solutions I've seen can only return the cache value as a client response, not use it within a "location" block for further routing.

I'm open to any ideas on how to pin a request to a specific upstream using a header value that doesn't rely on hardcoding a map or IP/URI hashing.

Thanks in advance, I've been stuck on this for over 5 hours. 🙁

Best Answer

i have same issue, i figure out just with "hash" method

upstream backend {
    # if you use Tengine (https://github.com/alibaba/tengine)
    # consistent_hash $http_customheadername; 
    hash $http_customheadername; 

    server 127.0.0.1:8080;
    server 127.0.0.1:8081;
    server 127.0.0.1:8082;
}
server {
    listen       80;
    server_name  test2.com;
    default_type  text/plain;

    location / {
        proxy_pass http://backend;
    }
}

server {
    listen 8080;
    server_name _;

    location / {
        echo "8080";
    }
}
server {
    listen 8081;
    server_name _;

    location / {
        echo "8081";
    }
}
server {
    listen 8082;
    server_name _;

    location / {
        echo "8082";
    }
}

you can set you unique value to header.

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