Isn't it ironic that even the writers of this article don't follow these rules in the examples on that page?
There is "Mistake 3: Not Enabling Keepalive Connections to Upstream Servers", where it says:
In the location{} block that forwards requests to an upstream group, include the following directives along with the proxy_pass directive:
proxy_http_version 1.1;
proxy_set_header "Connection" "";
Then, at "Mistake 10: Not Taking Advantage of Upstream Groups", the "location" block does not include these two directives, even though the "upstream" block contains a "keepalive" directive.
There is "Mistake 3: Not Enabling Keepalive Connections to Upstream Servers", where it says:
Then, at "Mistake 10: Not Taking Advantage of Upstream Groups", the "location" block does not include these two directives, even though the "upstream" block contains a "keepalive" directive.