Category: sysadmin

Ever googled for Nginx configuration? For example, how to redirect http://www.example.com to http://example.com? I have, and guess what, most of the top results are wrong or inefficient. All of these are documented in a Pitfalls page on the Nginx wiki. I’m just going to point out the parts of my config I’ve optimized recently with great help from the Nginx wiki.

Redirect from www to non-www

Nginx wiki recommends using return, but the version in Ubuntu 10.04 doesn’t seem to support it, so I use this:

rewrite ^ //nigelb.me$request_uri? permanent;

Static files

Set the Expires and Cache-Control headers with the expires header. Another thing I do is turn off access log for static files.

location ~ ^/(img|js|css)/ {         expires 30d;         access_log off; }

Running PHP with Nginx

Most PHP applications only have an index.php file that needs to be executed, everything else is usually an include.

location ~ index.php$ {         include fastcgi_params;         fastcgi_pass    unix:/tmp/php.socket; }

Remember to place your root directive outside any location block. Then, you can add another route for static files, just so that Nginx can serve them instead of that request going to PHP.

location ^~ /pub/ { }

By no means are these meant to be authoritative, and newer versions of Nginx lets you use try_files instead of some of what I’ve done.

TL;DR: Use the Nginx Wiki. RTFM.

Update: Lyz pointed out that the default config file that come with the CentOS packages on the Nginx website put root inside the location block instead of outside. She’s just helped me verify that and I verified the same problem with the Ubuntu packages from the Nginx website.

‘Amazon Relational Database Service (Amazon RDS) is a web service that makes it easy to set up, operate, and scale a relational database in the cloud. It provides cost-efficient and resizable capacity while managing time-consuming database administration tasks, freeing you up to focus on your applications and business.’ – Amazon RDS Website

Amazon RDS uses UTC by default. Personally, I think systems should use UTC by default, but at my work place, all systems are in IST, which means we want the RDS to work in IST too. So, we have this hack of setting the init_connect parameter to set time_zone = 'Asia/Kolkata';. This works great, except when you have to restart RDS. We’ve had to restart our instance twice so far, both times leading to considerable downtime, pain, and grief because of this hack (thankfully, the RDS machine is a backup machine and not used in production).

When it happened the first time, my ex-colleague did the modification and all I did note down was to remove the init_connect parameter. When it happened the second time, I remembered and set the init_connect parameter to an empty string, which I thought would work. Unfortunately, it didn’t. We talked to Amazon Support and now I know that when it happens, I should not be setting it to an empty value, but resetting instead.

rds-reset-db-parameter-group my-params --parameters 'name=init_connect,method=immediate' 

This post is for all those poor souls who might make the same mistake as me as well as a note to myself (though I suspect I’ll never forget this lesson :P) 🙂