Allow proxy_http_version to use variables

[whitlockjc@…]

I would like to conditionally set the proxy_http_version such that the requested HTTP version is used for the upstream request instead of locking it down to 1.0 or 1.1. My attempts at doing this have failed because proxy_http_version does not allow you to use a variable to set its value. Here was what I thought was the intuitive approach to this:

events {}
http {
  map $http_version $proxy_http_version {
    default 1.0;
    "1.1"   1.1;
  }

  proxy_http_version $proxy_http_version;

  server {
    listen 9999 default_server;
    return 444;
  }
}
daemon on;

Of course, that results in the following error: nginx: [warn] invalid value "$proxy_http_version" in /etc/nginx/nginx.conf:8, which is because the variable is a string but proxy_http_version If proxy_http_version was allowed to be set via a variable value, I could use the same HTTP version of the request for the upstream request.

I also tried a different version using if but proxy_http_version isn't allowed in an if either so both attempts at solving this have failed. I worried about setting proxy_http_version to 1.1 always to work around the known issues I'm facing (WebSockets and streaming APIs) but maybe that's the only solution?

[Maxim Dounin]

Just use proxy_http_version 1.1. Most modern backends handle this just fine, and there are no known negative effects. If you want to limit proxy_http_version 1.1 to minimal set of requests, use appropriate location for URIs where you need HTTP/1.1.

If really needed, proxy_http_version can be used conditionally by using different locations and switching them using if + return + error_page. Though this is not something needed in this particular case.

[whitlockjc@…]

Thanks.