13 July 2015

Setting up Nginx as a reverse proxy for Apache with SSL termination

Reverse Proxy diagram from Wiki Commons
We're currently hosting client sites on a Rackspace server and using their Load Balancer feature as a way to terminate SSL and not have to have multisite certificates.

We only attach one node to the Load Balancer so we're paying for more than we're using.  My proof of concept is to use Nginx to terminate SSL certificates and proxy to the Apache server.  This will save us £ 225 per load balancer, and since we're using ten of them that's quite a significant saving.

My first step was to spin up a free tier EC2 instance running Ubuntu 14.04 LTS.  I guess you can replace this with your favourite cloud or on-the-metal server.

Then I installed my packages. These are the ones I remember so YMMV.

 sudo apt-get install nginx apache2 fail2ban php5-fpm mcrypt php5-mcrypt openssl php5-cli php5 libapache2-mod-php  

My network diagram is slightly different from the picture for this post in that the web server is hosted on the same machine as the proxy.

I decided to run Apache on port 8000 and listen only to connections from localhost. Nginx would listen on port 80 and forward requests to Apache. I decided to let Nginx serve static content because it's pretty quick at doing so and this saves Apache from being overwhelmed by requests.

Configuring Apache

My first port of call was to edit /etc/apache2/ports.conf and make sure that my Listen line looks like this: Listen 127.0.0.1:8000

Then I created two virtual hosts to test with.  Here's a sample:

 <VirtualHost *:8000>  
      ServerName dummy1.mydomain.co.uk  
      ServerAdmin webmaster@localhost  
      DocumentRoot /var/www/dummy3/  
      ErrorLog ${APACHE_LOG_DIR}/dummy3_error.log  
      CustomLog ${APACHE_LOG_DIR}/dummy3_access.log combined  
 </VirtualHost>  

I made a simple index.php file in two new directories /var/www/dummy1 and /var/www/dummy3 which just output two server variables for me to test with. I also copied an image file into those directories so that I could check how static assets would be served.

 <?php  
 echo $_SERVER['SCRIPT_FILENAME'] . '<br>';  
 echo $_SERVER['SERVER_SOFTWARE'] . '<br>';  

Configuring Nginx

I decided to use self-signed certificates for testing and reserve dummy2 for a trial run of a free ssl certificate.  There are quite a few certificate signers who will give you a 30 day certificate to trial.

I created an /etc/nginx/ssl directory because for some reason I don't like to contaminate my conf.d directory and made subdirectories for my sites under that.

I created self-signed certificates (commands are at the top of my host file) and set up the vhosts like this:

Now when I hit a static file on HTTP or HTTPS then Nginx serves it up directly. Inspecting the response headers with your favourite browsers debug tool will confirm that images are served by Nginx. Visiting the index file shows that it's loading the correct one and is being handled by Apache. Lastly, checking the certificate will show you that each site is using its own certificate.

That has the potential of saving my company £ 2200, which is a happy thing to be able to do in your first week while your boss is watching :)
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