Cloudflare and websockets with SSL (free Cloudflare accounts block websocket connection)

Hi.

I have similar problem but I'm not using SSL

This is my basic NGINX configuration:

upstream gitlab_mattermost {
    server 127.0.0.1:8065;
}

map $http_upgrade $connection_upgrade {
    default upgrade;
    ''      close;
}

server {
    listen 80;
    server_name domain;
    server_tokens off;
    client_max_body_size 128M;

    access_log  /var/log/nginx/gitlab_mattermost_access.log;
    error_log   /var/log/nginx/gitlab_mattermost_error.log;

    location / {
        proxy_redirect          off;

        proxy_set_header   X-Forwarded-Proto http;
        proxy_set_header   Host              $http_host;
        proxy_set_header   X-Real-IP         $remote_addr;
        proxy_set_header   X-Forwarded-For   $proxy_add_x_forwarded_for;
        proxy_set_header   X-Frame-Options   SAMEORIGIN;

        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;

        proxy_pass http://gitlab_mattermost;
    }

    location /api/v1/websocket {
        proxy_pass http://gitlab_mattermost;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
    }
}

On Mattermose logs:

[2016/04/08 11:55:11 CEST] [EROR] websocket connect err: websocket: could not find upgrade header with token 'websocket'
[2016/04/08 11:55:11 CEST] [EROR] /api/v1/websocket:connect code=500 rid=n9njd8fnx7gymxrrb19wbji4ie uid=pq1jp3d5mf885cjt8jm5te11io ip=unknown Failed to upgrade websocket connection [details: ]

My Cloudflate is disabled (gray cloud).

Any idea?