nginx proxy retry while backend is restarting

Question

Nginx returns 502 while the backend is restarting. How can I make nginx proxy retry N times with M seconds delay? Is there a plugin or something else?

Answer 1

Closest thing I know is this project, but I never used. I know that varnish has backend checking, maybe you want to take a look on it.

Answer 2

I found that Nginx took ~2 seconds to exhaust attempts if you specified hundreds of instances of the same backend:

    server  localhost:8080 max_fails=0;
    server  localhost:8080 max_fails=0;
    server  localhost:8080 max_fails=0;
    server  localhost:8080 max_fails=0;

(.... er, repeat as required!)

Yes, a horrendous kludge - but it does add a degree of tenacity...

Even worse than that, you could use:

    server  localhost:8080 max_fails=0;     
    server  localhost:80 backup;        

Assuming Nginx is running on port 80, this would try to continually loop the request around Nginx until localhost:8080 responds. I.e. retry an infinite(?) number of times with zero seconds delay.

I'll get back to my padded cell now....