Hi,
I have centos server, where both Apache and Nginx are installed already, Varnish is not installed. Now I run Nginx, Apache is stopped (and its config file is not proper now, you should configure it as well). I want you to first install Varnish and configure it to run in front of Apache.
I have four websites under /var/www, which are:
/var/www/ee
/var/www/gonderme
/var/www/komsual
/var/www/yelloretail
You should configure Apache to run these websites without changing the owner and group of the folders, so that it will be easy to switch between nginx and apache.
Then you should write a script which accepts a parameter, to control the web servers (apache and nginx). Let's say that the script is called wserver, so it should work like this:
wserver nginx
It should stop Apache and Varnish if they are running and run Nginx
wserver apache
It should stop Nginx if it is running, and run Apache only (without Varnish)
wserver apache_varnish
It should stop Nginx if it is running, and run Apache and Varnish
Your task looks really trivial, as long as your current server configs are not too messy. I assume - not.
Still for such small tasks communication and project handling overheads are significant thus I can't offer better price.
I'm an experienced Linux system admin, and enjoy doing exactly things like this. I'm working with apache, nginx and varnish on a daily basis, I'd be glad to help you with this.