It sounds like you want to control what upstream servers are available based on a set of criteria.
This setup might do what you want, just not implemented in the exact way you desire: https://medium.com/@sigil66/dynamic-nginx-upstreams-from-consul-via-lua-nginx-module-2bebc935989b On Tue, Oct 17, 2017 at 7:01 AM, rnmx18 <nginx-fo...@forum.nginx.org> wrote: > Hi, > > I have a requirement to de-select or exclude one or more servers from an > upstream group, if that server is either just newborn or exhausted > (overloaded or showing reduced performance). > > So, consider there are servers A, B and C in the upstream group. An > external > program periodically checks A, B and C and keeps track of different > parameters (uptime, average response time etc), and assigns a "good" or > "bad" status flag to each of them. > > I would like to implement a mechanism in NGINX, in which it can > periodically > (say every 5 minutes) communicate with this external program and collect > the > status flag for A,B and C. This would be an HTTP communication with a > response in a parse-able text format. Assume if B is reported as "bad", I > would like to exclude B temporarily, till I get a "good" value back for it. > > I am aware of the native upstream healthcheck mechanism in NGINX. > > However, the requirement here is to bring some additional parameters into > consideration for the selection of upstream. > > I would like to know whether this is feasible to realize in NGINX. Could > someone please explain some design insights for this problem? > > Going a bit deeper, I could identify the following potential requirements > or > questions? > > a) Should I depend on both (a) the passive upstream check native to NGINX > and (b) the status value to be obtained from the external process? I think > since the native health check is passive in nature (like when NGINX tries > to > connect to an upstream when it wants to proxy the request), it is beyond my > programmable-control. So, I needn't worry about that. What I should be > worried is about enabling NGINX to dynamically exclude a particular server, > based on a "bad" feedback from the external process. > > b) How to communicate periodically with the external process over HTTP? How > can I get an HTTP client functionality in NGINX to send an external request > and process the response? Can I build this functionality as an NGINX > module? > > c) Last but not the least, I would need some mechanism by which I should be > able to map the server(s) reported as "bad" to the configured upstream > servers, and then temporarily exclude them (mark down), and later include > them when the status changes to "good". > > Thanks > Rajesh > > Posted at Nginx Forum: https://forum.nginx.org/read. > php?2,276912,276912#msg-276912 > > _______________________________________________ > nginx mailing list > nginx@nginx.org > http://mailman.nginx.org/mailman/listinfo/nginx >
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