Exact match (=) in Nginx - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the = symbol mean in an nginx location block?

It means the location will match the request URI exactly, without any extra characters or variations.

beginner

How does nginx treat a location = /path compared to location /path?

The = /path matches only the exact URI /path, while /path matches any URI starting with /path.

intermediate

Why use = for exact match in nginx locations?

To ensure that only requests with the exact URI are handled by that block, avoiding partial or prefix matches.

intermediate

What happens if multiple nginx location blocks match a request URI and one uses =?

The exact match location with = is chosen first before prefix or regex matches.

beginner

Write a simple nginx location block using exact match for URI /hello.

location = /hello { return 200 "Hello exact match!"; }

What does location = /test match in nginx?

A All URIs

B Any URI starting with /test

C Any URI containing /test anywhere

D Only the URI exactly equal to /test

The '=' sign means exact match, so only the URI exactly '/test' matches.

If you have location = /foo and location /foo, which handles the request to /foo?

A location /foo

B Neither

C location = /foo

D Both equally

Exact match with '=' has higher priority and will handle the request.

Can location = / be used to match only the homepage URI exactly?

A Yes

B No

C Only with regex

D Only with prefix

Using '=' with '/' matches only the exact homepage URI.

What is the main benefit of using exact match = in nginx locations?

A Matches all URIs

B Faster matching for specific URIs

C Allows regex inside location

D Disables caching

Exact match is faster and more precise for specific URIs.

Which symbol is used in nginx to specify an exact match in a location block?

A =

B ^~

C ~

D *

The '=' symbol is used for exact match in nginx location blocks.

Explain how nginx processes location blocks when one uses exact match (=) and others use prefix matches.

Think about priority order in nginx location matching.

Describe a scenario where using exact match (=) in nginx location is better than prefix match.

Consider when you want to be very precise about which requests are handled.

Practice

1. What does the = sign mean in an nginx location block?

easy

A. It matches URLs ending with the given path.

B. It matches the exact URL path only.

C. It matches URLs containing the given path anywhere.

D. It matches any URL starting with the given path.

Solution

1. Step 1: Understand nginx location matching

   The = sign in nginx location means the URL must match exactly the specified path.

2. Step 2: Compare with other matching types

   Other types like prefix matching use location /path without =, which matches URLs starting with that path.

3. Final Answer:

   It matches the exact URL path only. -> Option B

4. Quick Check:

   Exact match = exact URL [OK]

Hint: Exact match uses = sign, no extra path allowed [OK]

Common Mistakes:

• Thinking = matches URL prefixes
• Confusing = with regex matching
• Assuming = matches URLs containing the path

2. Which of the following is the correct syntax to define an exact match location for URL /about in nginx?

easy

A. location /about { }

B. location /about = { }

C. location ~ /about { }

D. location = /about { }

Solution

1. Step 1: Recall nginx exact match syntax

   Exact match uses location = /path { } syntax, where = comes immediately after location.

2. Step 2: Check other options

   location /about = { } places = after path, which is invalid. location ~ /about { } uses regex (~), not exact match. location /about { } is prefix match.

3. Final Answer:

   location = /about { } -> Option D

4. Quick Check:

   Exact match syntax = location = /path [OK]

Hint: Put = right after location for exact match [OK]

Common Mistakes:

• Placing = after the path
• Using regex (~) instead of = for exact match
• Omitting = for exact match

3. Given this nginx config snippet:

location = /test {
  return 200 'Exact match';
}
location /test {
  return 200 'Prefix match';
}

What will be the response body when accessing URL /test?

medium

A. Exact match

B. Prefix match

C. 404 Not Found

D. 500 Internal Server Error

Solution

1. Step 1: Identify matching location for /test

   The URL /test matches exactly the location = /test block because of the exact match sign =.

2. Step 2: Understand nginx location priority

   Exact match locations have higher priority than prefix matches, so the first block is used and returns 'Exact match'.

3. Final Answer:

   Exact match -> Option A

4. Quick Check:

   Exact match location wins for exact URL [OK]

Hint: Exact match location overrides prefix for exact URL [OK]

Common Mistakes:

• Choosing prefix match response for exact URL
• Assuming 404 if exact match exists
• Confusing order of location blocks

4. You wrote this nginx config:

location = /home {
  proxy_pass http://backend;
}
location /home {
  proxy_pass http://frontend;
}

But requests to /home are always sent to http://frontend. What is the likely problem?

medium

A. The exact match location block is not matched because of a syntax error.

B. The exact match location block is missing a trailing slash.

C. The exact match location is overridden by prefix match due to order.

D. The exact match location block is ignored because proxy_pass is invalid.

Solution

1. Step 1: Check syntax of exact match location

   The exact match location location = /home { ... } may have a syntax error like missing semicolon after proxy_pass, causing nginx to ignore it.

2. Step 2: Consider nginx matching rules

   Exact match locations have highest priority and should be matched first. If requests go to frontend, likely the exact match block is ignored due to a syntax error or config reload issue.

3. Step 3: Identify common mistake

   Often, missing semicolons or incorrect proxy_pass URL cause nginx to ignore the block silently.

4. Final Answer:

   The exact match location block is not matched because of a syntax error. -> Option A

5. Quick Check:

   Syntax errors cause nginx to ignore blocks [OK]

Hint: Check syntax errors if exact match ignored [OK]

Common Mistakes:

• Assuming order affects exact match priority
• Missing semicolon after proxy_pass
• Confusing trailing slash importance

5. You want to serve a special static page only when the URL is exactly /special. Which nginx config snippet correctly achieves this without affecting other URLs starting with /special?

hard

A. location /special { root /var/www/special; }

B. location ~ /special { root /var/www/special; }

C. location = /special { root /var/www/special; }

D. location ^~ /special { root /var/www/special; }

Solution

1. Step 1: Understand exact match requirement

   To serve only the exact URL /special, use location = /special which matches exactly that path.

2. Step 2: Analyze other options

   location /special { root /var/www/special; } matches any URL starting with /special. location ~ /special { root /var/www/special; } uses regex to match URLs containing /special anywhere. location ^~ /special { root /var/www/special; } uses prefix match with ^~, which matches prefixes but not exact only.

3. Final Answer:

   location = /special { root /var/www/special; } -> Option C

4. Quick Check:

   Exact match = location = /path [OK]

Hint: Use = for exact URL, not prefix or regex [OK]

Common Mistakes:

• Using prefix match for exact URL
• Overcomplicating with regex
• Confusing ^~ with exact match