This will set the nginx proxy_read_timeout
for your dokku app to 10 minutes.
dokku plugin:install https://github.com/investtools/dokku-long-timeout-plugin.git
previous versions (0.3.x and below) of dokku require a manual process to install plugins
cd /var/lib/dokku/plugins
git clone https://github.com/investtools/dokku-long-timeout-plugin.git
dokku plugins-install