Common mistakes I made while using Nginx

These are a couple frequent mistakes that I made while working on Nginx. These are caused because apache2 is present by default in most of the ubuntu servers.

1. Forgetting to Disable apache2

Sometimes, when you try to restart/start nginx, using sudo service nginx (re)start, you see the following error

If you check the logs at var/logs/nginx/error.log file, it says something like this

Nginx job is to listen to port 80, but when you tried to restart it, it failed because it was already being listened by some other process. To see, who is listening at port 80, use the command sudo lsof -i :80, and you see that apache2 is the criminal! It was apache2, who was listening to the 80, preventing nginx from listening to the port. You can’t have 2 web servers listening at the same port 80.

Where did apache2 come from?

apache2 is installed by default in most of the Ubuntu servers. And when the machine boots, the services start in the alphabetical order. Since apache2 comes before nginx alphabetically, apache2 gets hold of the port 80.

Solution: Disable apache2, so that it never start automatically on its own when you reboot your server. To do that,

1. Stop apache2 - sudo service apache2 stop
2. Disable using systemctl - sudo systemctl disable apache2

or it can be done in one line - sudo systemctl disable --now apache2, this will both stop and disable apache2.

Now you can start nginx successfully

Suggestion: Since mostly Ubuntu servers have apache2 enabled by default, soon after you have spun your instance you can disable apache2 to avoid any troubles in future.

2. Unlinking the default page

You have your nginx configuration in a separate file,say your-domain.com, (which is a popular practice) in /etc/nginx/sites-available. But when you visit the site, it shows the Ubuntu default page something like this

This is because the configuration in default file in /etc/nginx/sites-available is given priority over your configuration, which is written in separate file. To disable the Ubunut default page, you can simply remove the symlink of default using unlink in /etc/nginx/sites-enabled directory using - sudo unlink /etc/nginx/sites-available/default.

Apendinx

This happened to me twice till now - once while working on KWoC, the other time on project-ias. Thanks to Mukul Mehta, for explaining the cause of error during KWoC. I was lucky to be present in the call as a mere spectator, when he was fixing this.