soheilhy/nginxproxy.md

## nginxproxy.md

      
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              nginxproxy.md
            
          
    Virtual Hosts on nginx (CSC309)

When hosting our web applications, we often have one public IP
address (i.e., an IP address visible to the outside world)
using which we want to host multiple web apps. For example, one
may wants to host three different web apps respectively for
example1.com, example2.com, and example1.com/images on
the same machine using a single IP address.
How can we do that? Well, the good news is Internet browsers
send the domain name inside HTTP requests and all we need to do
is to parse the requested domain name and URL and then route the
HTTP request to the actual web server.
Oh, do I really need to parse HTTP requests? You can if you
really want to, but there are lots of tools and technologies that
readily do this for you. In this tutorial, we walk you through
how you can use nginx to proxy multiple web applications.
Install nginx

CDF @UofT

We have prepared pre-copmiled binaries for your.
You need to download nginx.tar.gz
and uncompress it:
$ wget http://www.cs.toronto.edu/~soheil/csc309/nginx.tar.gz && tar -xvzf nginx.tar.gz

It creates an nginx directory for you. The config file
is in nginx/conf/nginx.conf.
We have provided a script named nginx in the directory.
To run nginx, go to the nginx directory (cd nginx) and
run ./nginx ....

Ubuntu

Install nginx using apt-get:
$ sudo apt-get install nginx
Notes:

The part of the nginx's config file we need resides in /etc/nginx/sites-enabled/default.
To edit the config file or run nginx, you need to use sudo.

Mac OS

Install homebrew, and then install nginx using brew:
$ brew install nginx
Notes:

nginx's config file is in /usr/local/etc/nginx/nginx.conf.
To edit the config file or run nginx, you need to use sudo:
sudo nano /usr/local/etc/nginx/nginx.conf and
sudo nginx ...

Configuration

Step 1 -- Booting Servers for Virtual Hosts

Write three different node applications running on different ports
(say 8080, 8181, 8282) on your machine.
Step 2 -- Configure nginx's Port

To do so, you need to edit your nginx config file.
In the config file, find the server section:
server {
    listen       80;
    ...
    location / {
       ...
    }
    ...
}

If you're using CDF, make sure you change 80 to a vacant port number
(ask for one from your instructor). If not, you can keep using 80 or
change the port if you will.
Test nginx

Run ./nginx on CDF, or run sudo nginx on your local machine.
Open the browser and log on to localhost:$PORT (replace $PORT with
the port number you configured for nginx).

Step 3 -- Configure /

Let say we want to configure nginx to route requests for
/, /blog, and /mail, respectively onto
localhost:8080, localhost:8181, and localhost:8282.
                  +--- host --------> node.js on localhost:8080
                  |
users --> nginx --|--- host/blog ---> node.js on localhost:8181
                  |
                  +--- host/mail ---> node.js on localhost:8282

To route /, you need to edit your nginx config file.
In the config file, find the server section:
server {
    listen       80;
    ...
    location / {
       ...
    }
    ...
}

This section is simply telling nginx how it should serve HTTP requests.
Now, change the location section to this snippet:
server {
    listen       ...;
    ...
    location / {
        proxy_pass http://127.0.0.1:8080;
    }
    ...
}

proxy_pass simply tells nginx to forward requests to / to the
server listening on http://127.0.0.1:8080.
Step 4 -- Reload nginx's Configuration

To reload nginx's configuration run:
nginx -s reload on your machine.
Referesh your browser. Do you see the output from your node.js application?
If yes, you are all set. If no, there is a problem with your config.
Step 5 -- Add /blog and /mail

To redirect /mail and /blog, you simply need to add new entries
the location section in the config file:
server {
    listen       ...;
    ...
    location / {
        proxy_pass http://127.0.0.1:8080;
    }
    
    location /blog {
        proxy_pass http://127.0.0.1:8181;
    }

    location /mail {
        proxy_pass http://127.0.0.1:8282;
    }
    ...
}

Step 6 -- Reload Your nginx Configuration

Run nginx -s reload on your machine.
Log onto localhost:$PORT/blog in your browser.
Do you see the output from your second node.js application?
Then log onto localhost:$PORT/mail.
Do you see the output from your third node.js application?
If yes & yes, you are all set. If no, there is a problem with your config.
Step 7 -- Rewriting Requests

Now as you might have noticed in Step 6, nginx sends the same
HTTP request to your node.js web apps which results into a 404 error.
Why? Because, your node.js web application serves requests from /
not from /blog and /mail. But, nginx is sending requests to /blog and
/mail.
To fix this issue, we need rewrite the URL so that it matches the URL
you can serve on your node.js applications.
To correctly rewrite URLs change your config file to match the following snippet:
server {
    listen       ...;
    ...
    location / {
        proxy_pass http://127.0.0.1:8080;
    }
    
    location /blog {
        rewrite ^/blog(.*) /$1 break;
        proxy_pass http://127.0.0.1:8181;
    }

    location /mail {
        rewrite ^/mail(.*) /$1 break;
        proxy_pass http://127.0.0.1:8282;
    }
    ...
}

This rewrite commands are simple regular expressions that transform
strings like /blogWHAT_EVER and /mailWHAT_EVER to /WHAT_EVER
in the HTTP requests.
Step 8 -- Reload and Test.

All set?
Exercise 1

Configure your nginx to redirect URLs from /google to http://www.google.com
Step 9 (optional) -- Redirecting Based on Host Name

Let say you want to host example1.com, example2.com, and example3.com
on your machine, respectively to localhost:8080, localhost:8181, and
localhost:8282.
Note: Since you don't have access to a DNS server, you should
add domain name entries to your /etc/hosts (you can't do this on CDF machines):
...
127.0.0.1 example1.com example2.com example3.com
...

To proxy eaxmple1.com we can't use the location part of the default server.
Instead we need to add another server section with a server_name set
to our virtual host (e.g., example1.com, ...), and then a simple location
section that tells nginx how to proxy the requests:
server {
    listen       80;
    server_name  example1.com;

    location / {
        proxy_pass http://127.0.0.1:8080;
    }
}

server {
    listen       80;
    server_name  example2.com;

    location / {
        proxy_pass http://127.0.0.1:8181;
    }
}

server {
    listen       80;
    server_name  example3.com;

    location / {
        proxy_pass http://127.0.0.1:8282;
    }
}


Simple, ha?!