google analytics in nginx

conf.d_yourdomain.com.conf

server {
  listen 80;
  server_name yoursite.com;

  # set $google_analytics_id and include the google_analytics file below
  set $google_analytics_id "UA-12345678-9";
  include /usr/local/nginx/conf/google-analytics.conf;

  location / {
    # your normal config goes here...

    # call the @ga location as a post_action
    post_action @ga;
  }
}

google-analytics.conf

# send logs for all traffic (including non-html) to google analytics
#
# in server block:
#  set $google_analytics_id "UA-THECORRECT-ID";
#  include /usr/local/nginx/conf/conf.d/yoursite.com.conf;
#
# in location blocks:
#  post_action @ga;

userid on;
userid_name cid;
userid_expires 2y;
userid_path "/; Secure; SameSite=None";

set $ga_dp $uri;
set $ga_host $host;

# userid is contained in uid_got or uid_set, depending on if it's already been set
# also the cookie variable name is included (e.g. cid=ASDF), so no need to specify it in the query params
set $cid $uid_got$uid_set;

location @ga {
    internal;

    # don't track internal requests
    if ($internal_request) {
        return 200;
        break;
    }

    resolver 8.8.8.8 ipv6=off;
    proxy_ignore_client_abort on;
    proxy_next_upstream timeout;
    proxy_connect_timeout 1s;

    proxy_method GET;
    proxy_pass_request_headers on;
    proxy_pass_request_body off;

    proxy_set_header Host "www.google-analytics.com";
    proxy_set_header Content-Length "";
    proxy_set_header Cookie "";
    proxy_set_header Referer "";

    set $ga_api "https://www.google-analytics.com";

    # DOWNLOAD SIZE TRACKING
    # Google Analytics doesn't track download sizes out of the box.
    # Here we are using a custom metric (cm1) and sending the value of nginx's bytes_sent
    proxy_pass $ga_api/collect?v=1&dp=/$ga_dp&dh=$ga_host&tid=$google_analytics_id&$cid&uip=$remote_addr&t=pageview&cm1=$bytes_sent&dr=$http_referer;
}

nginx.conf

http {
  # your normal config goes here
  
  geo $internal_request {
    default 0;
    127.0.0.1 1;
  }
  
  # add the lines above somewhere BEFORE your virtual host configs are included
  # e.g. BEFORE include /usr/local/nginx/conf/conf.d/*.conf;
}

We clear out Referer header with proxy_set_header Referer "";, because we will instead pass the value along with &dr=$http_referer.
I don't remember why, but Analytics didn't recognize Referer header with the /collect/ API.