Trailing slash normalization in Nginx - Mini Project: Build & Apply

Trailing Slash Normalization in nginx

📖 Scenario: You are managing a website using nginx as the web server. Sometimes users visit URLs with or without a trailing slash (like /about or /about/), which can cause duplicate content or broken links. To keep URLs consistent and improve SEO, you want to make sure all URLs end with a trailing slash.

🎯 Goal: Configure nginx to automatically add a trailing slash to URLs that don't have one, except for requests to files (like image.png) or the root URL.

📋 What You'll Learn

Create a server block with a root location

Add a variable to check if the URL ends with a slash

Write a rewrite rule to add a trailing slash if missing

Test the configuration by printing the final rewritten URL

💡 Why This Matters

🌍 Real World

Websites often have inconsistent URLs with or without trailing slashes. Normalizing URLs improves user experience and search engine ranking.

💼 Career

DevOps engineers and site reliability engineers frequently configure web servers like nginx to handle URL normalization and redirects for production websites.

1

Create the basic nginx server block

Write an nginx server block with listen 80; and server_name example.com;. Inside it, create a location / block with root /var/www/html;.

Nginx

# Your code here

Need a hint?

Start by defining a server block listening on port 80 for example.com. Then add a location block for the root path with the root directory.

2

Add a variable to check for trailing slash

Inside the location / block, add a variable $has_trailing_slash that is 1 if the request URI ends with a slash, otherwise 0. Use the set directive and if condition with $request_uri.

Nginx

server {
    listen 80;
    server_name example.com;

    location / {
        root /var/www/html;
        # Your code here
    }
}

Need a hint?

Use set to create the variable and an if block with a regex to check if $request_uri ends with a slash.

3

Add rewrite rule to append trailing slash

Inside the location / block, add an if condition that checks if $has_trailing_slash is 0 and the URI does not contain a dot (to exclude files). If true, use rewrite to redirect to the same URI with a trailing slash and a 301 status.

Nginx

server {
    listen 80;
    server_name example.com;

    location / {
        root /var/www/html;

        set $has_trailing_slash 0;
        if ($request_uri ~ "/$") {
            set $has_trailing_slash 1;
        }

        # Your code here
    }
}

Need a hint?

Use nested if blocks to check both conditions, then use rewrite with permanent to redirect.

4

Print the final rewritten URL for testing

Add a return 200 directive inside the location / block that returns the current URI with a trailing slash if it was added, or the original URI otherwise. Use return 200 "$request_uri"; to display the URI.

Nginx

server {
    listen 80;
    server_name example.com;

    location / {
        root /var/www/html;

        set $has_trailing_slash 0;
        if ($request_uri ~ "/$") {
            set $has_trailing_slash 1;
        }

        if ($has_trailing_slash = 0) {
            if ($request_uri !~ ".+\\..+") {
                rewrite ^(.*)$ $1/ permanent;
            }
        }

        # Your code here
    }
}

Need a hint?

Use return 200 "$request_uri"; to output the current URI for testing purposes.