Trailing slash normalization in Nginx - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this nginx rewrite rule?

Given the nginx configuration snippet below, what will be the final URL after a client requests http://example.com/path/?

Nginx

location /path/ {
    rewrite ^/(.*)/$ /$1 permanent;
}

A Redirects to http://example.com/path (without trailing slash)

B Redirects to http://example.com/path/ (no change)

C Returns 404 Not Found

D Redirects to http://example.com//path (double slash)

💡 Hint

Look at the rewrite regex and replacement carefully.

The rewrite rule removes the trailing slash by matching any path ending with a slash and redirecting to the same path without it.

❓ Configuration

intermediate

Choose the correct nginx config to add trailing slash if missing

Which nginx configuration snippet will redirect http://example.com/path to http://example.com/path/ (adding trailing slash) using a 301 redirect?

A rewrite ^/(.*)$ /$1/ permanent;

B rewrite ^([^.]*[^/])$ $1/ permanent;

C rewrite ^/(.*)/$ /$1 permanent;

D rewrite ^([^.]*[^/])$ /$1 permanent;

💡 Hint

Focus on matching URLs without trailing slash and not containing a dot.

Option B matches URLs that do not end with a slash and do not contain a dot (to exclude files), then adds a trailing slash with a permanent redirect.

❓ Troubleshoot

advanced

Why does this trailing slash removal rule cause a redirect loop?

Consider this nginx config:

location /app/ {
    rewrite ^/(.*)/$ /$1 permanent;
    proxy_pass http://backend/;
}

Why might this cause a redirect loop when accessing /app/?

A Because the rewrite removes the slash but the location requires it, causing repeated redirects

B Because proxy_pass is missing a trailing slash, causing wrong backend path

C Because permanent redirects are cached and never updated

D Because the regex does not match the URL path

💡 Hint

Think about how location matching and rewrite interact.

The rewrite removes the trailing slash, but the location block matches only URLs with trailing slash, so nginx redirects again, causing a loop.

✅ Best Practice

advanced

Which approach is best for consistent trailing slash handling in nginx?

You want all URLs to have no trailing slash except for directories which must have it. Which nginx config approach is best?

A Use proxy_pass without any rewrite rules and handle trailing slashes in backend

B Use a single rewrite rule to remove all trailing slashes unconditionally

C Use separate location blocks for directories and files with rewrite rules to add or remove slashes accordingly

D Use rewrite rules to add trailing slashes to all URLs regardless of type

💡 Hint

Think about how nginx distinguishes directories and files.

Separate location blocks allow precise control: directories get trailing slash, files do not, avoiding redirect loops and confusion.

🧠 Conceptual

expert

What is the effect of this nginx config on URL normalization?

Analyze this nginx snippet:

if ($request_uri ~* ".+/$") {
    return 301 $scheme://$host$uri;
}

What does it do?

A Redirects URLs without a trailing slash to add one

B Does nothing because $uri is undefined

C Blocks access to URLs ending with a slash

D Redirects URLs ending with a slash to the same URL without the slash

💡 Hint

Look at the regex and the return statement carefully.

The if condition matches URLs ending with a slash and redirects to the same URL without the slash by using $uri which excludes the trailing slash.