gzip_types has no effect without setting gzip and gzip_proxied

I was just reading the NGINX documentation for the various directives in the nginx-proxy template because NGINX is all new to me (I've switched to nginx-proxy from a handcrafted Apache configuration).

I noted that gzip is off by default (http://nginx.org/en/docs/http/ngx_http_gzip_module.html#gzip). I checked the global NGINX configuration included in the Docker nginx image* and found that there are no overrides there so it really is off. I also confirmed empirically** that gzip is not being enabled using curl.

I would open a PR that adds gzip on above gzip_types, but I note that gzip_proxied must also be set to something other than its default of off for gzip to actually be enabled; there are several options (http://nginx.org/en/docs/http/ngx_http_gzip_module.html#gzip_proxied) and it's not clear to me what would be most appropriate for nginx-proxy's template.

Assuming I've not missed something, perhaps this issue can be used to discuss and agree on a sensible value for gzip_proxied, and then a PR can be made?

130 david@maple:~/Deploy/proxy/docker-gen⟫ sudo docker run -it --rm nginx:1 bash
root@7e1d979519b4:/# cd /etc/nginx/
root@7e1d979519b4:/etc/nginx# ls
conf.d  fastcgi_params  koi-utf  koi-win  mime.types  nginx.conf  scgi_params  uwsgi_params  win-utf
root@7e1d979519b4:/etc/nginx# cat nginx.conf | grep gzip
    #gzip  on;

**

david@ash:~$ curl -I -H "Accept-Encoding: gzip,deflate" https://www.dhpiggott.net
HTTP/1.1 200 OK
Server: nginx
Date: Sat, 04 Apr 2015 09:56:48 GMT
Content-Type: text/html
Content-Length: 3730
Connection: keep-alive
Last-Modified: Fri, 03 Apr 2015 22:46:34 GMT
ETag: "551f184a-e92"
Accept-Ranges: bytes
Strict-Transport-Security: max-age=15768000

compare to the result when I add gzip on and gzip_proxied any to my template:

david@ash:~$ curl -I -H "Accept-Encoding: gzip,deflate" https://www.dhpiggott.net
HTTP/1.1 200 OK
Server: nginx
Date: Sat, 04 Apr 2015 09:59:20 GMT
Content-Type: text/html
Connection: keep-alive
Last-Modified: Fri, 03 Apr 2015 22:46:34 GMT
ETag: W/"551f184a-e92"
Strict-Transport-Security: max-age=15768000
Content-Encoding: gzip

Read the nginx-proxy template and the NGINX gzip and gzip_proxied documentation, then reproduce the current behavior with the curl commands shown in the issue. Review the discussion to identify an agreed gzip_proxied value; done means the template uses the agreed settings and proxied responses are gzip-encoded when requested.