Configuring /etc/hosts to run an application

Question

I am using nginx, until now I was running my php applications on /usr/share/nginx/html which is the default document root when nginx is installed on centOS and like systems.

Now I had to create server blocks (or virtual hosts) to run another application, followed this tutorial (https://www.digitalocean.com/community/tutorials/how-to-set-up-nginx-server-blocks-virtual-hosts-on-ubuntu-14-04-lts) and ended up creating my application in /var/www/html.

On this process, as the tutorial states to edit etc/hosts to your public IP, this made another application run that is deployed on my LAN. I wanted it to run on my machine only, so I changed it to my local IP and made the following entry to hosts

192.168.0.38 dev.mysite.com www.dev.mysite.com 

Strangely, just after that I noticed my hostname had changed to

muUsername@dev instead of @localhost before

1. Please tell me why it happened and how to change it back.
2. Now the application runs when I access localhost in the browser, but not when I access dev.mysite.com, How to fix that?
3. On accessing www.dev.mysite.com I get my old application at the old webroot (uss/share/nginx/html) Why is this happening and how to fix this?

Need any more information, please comment.

Answer 1

1) It happens because you are setting up a FQDN for your machine and the hostname is assumed to be the subdomain part in this case. That's due to the behaviour of gethostname function. If you run hosname -f it will give you the FQDN and hostname -d will give you the domain name. Set your machine's name before all these FQDN.

Update : Didn't pay attention you were on centos, updated the second file location

/etc/hosts :

192.168.0.38 mymachine dev.mysite.com www.dev.mysite.com  

/etc/sysconfig/network:

HOSTNAME=mymachine  

Then reboot.

2) When you hit that domain name locally, the kernel will look for /etc/hosts content at some point and then route the request to your loopback interface. You probably missed a server name in your nginx configuration.

3) Change your document root path for this server name.

server {
    listen 80;
    server_name www.dev.mysite.com;
    root /var/www/dev.mysite.com;
}

server {
    listen 80 default_server;
    server_name _;
    return 301 http://www.dev.mysite.com;
}