Name

• ngx_http_upstream_dynamic_module

Description

• This module provides the functionality to resolve domain names into IP addresses in an upstream at run-time.
• It comes from Taobao Tengine @ http://tengine.taobao.org

Compilation

\#for nginx 1.10 or lower, use the patch http-upstream-dynamic.patch
\#for nginx 1.14 or higher, use the patch http-upstream-dynamic.patch-1.14.0+

patch -p0 < /path/to/nginx-http-upstream-dynamic-module/http-upstream-dynamic.patch

./configure --add-module=/path/to/nginx-http-upstream-dynamic-module

Examples

upstream backend {
    dynamic_resolve fallback=stale fail_timeout=30s;

    server a.com;
    server b.com;
}

server {
    ...

    proxy_pass http://backend;
}

Directives

dynamic_resolve

Syntax: dynamic_resolve [fallback=stale|next|shutdown] [fail_timeout=time]

Default: -

Context: upstream

Enable dynamic DNS resolving functionality in an upstream.

The 'fallback' parameter specifies what action to take if a domain name can not be resolved into an IP address:

• stale, use the original IP addresses resolved when tengine starts.
• next, go to next availiable server in the upstream.
• shutdown, finalize current request.

The 'fail_timeout' parameter specifies how long time tengine considers the DNS server as unavailiable if a DNS query fails for a server in the upstream. In this period of time, all requests comming will follow what 'fallback' specifies.

Notes

• It is a tengine module from https://github.com/alibaba/tengine/blob/master/src/http/modules/ngx_http_upstream_dynamic_module.c and made to work with nginx 1.9
• It follows original tengine license.