Location matching priority order in Nginx - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the order of location matching priority in nginx?

nginx matches locations in this order: 1) Exact match (=), 2) Longest prefix match, 3) Regular expression (~ or ~*), 4) If no match, default location (/).

beginner

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

The '=' symbol means an exact match. nginx will serve this location only if the request URI exactly matches the location path.

intermediate

How does nginx handle multiple prefix locations that match a request URI?

nginx chooses the longest matching prefix location among those without '=' or regex modifiers.

intermediate

What is the difference between '~' and '~*' in nginx location blocks?

'~' means case-sensitive regular expression match, while '~*' means case-insensitive regular expression match.

beginner

What happens if no location matches a request URI in nginx?

nginx uses the default location '/' if no other location matches the request URI.

Which location block does nginx check first when matching a request URI?

A Regular expression (~ or ~*)

B Longest prefix match

C Exact match (=)

D Default location (/)

nginx first checks for an exact match location block marked with '='.

If multiple prefix locations match, which one does nginx choose?

A Longest prefix

B Shortest prefix

C First defined in config

D Random

nginx selects the longest matching prefix location.

What does the '~*' modifier mean in an nginx location?

A Prefix match

B Case-sensitive regex

C Exact match

D Case-insensitive regex

'~*' means case-insensitive regular expression match.

When does nginx use the default location '/'?

A Always

B If no other location matches

C Only for exact matches

D Only for regex matches

nginx uses the default location '/' if no other location matches the request URI.

Which location type has the lowest priority in nginx matching?

A Default location (/)

B Prefix match

C Exact match (=)

D Regular expression (~ or ~*)

The default location '/' is used only if no other location matches.

Explain the priority order nginx uses to match a request URI to a location block.

Think about how nginx tries to find the most specific match first.

Describe the difference between prefix match and regular expression match in nginx location blocks.

Consider how nginx interprets the location block modifiers.

Practice

1. Which type of location block does nginx check first when matching a request URL?

easy

A. Prefix match without any modifier

B. Exact match using = modifier

C. Regular expression match using ~ or ~*

D. Prefix match with ^~ modifier

Solution

1. Step 1: Understand nginx location matching order

   nginx first looks for an exact match location block marked with =.

2. Step 2: Confirm priority of exact match

   If an exact match is found, nginx immediately uses it without checking other blocks.

3. Final Answer:

   Exact match using = modifier -> Option B

4. Quick Check:

   Exact match = first checked [OK]

Hint: Exact match with = is always checked first [OK]

Common Mistakes:

• Thinking prefix matches are checked before exact matches
• Confusing ^~ modifier priority
• Assuming regex matches are checked first

2. Which of the following is the correct syntax for a location block that uses a case-insensitive regular expression match?

easy

A. location ~ "/images/" { }

B. location ^~ "/images/" { }

C. location = "/images/" { }

D. location ~* "/images/" { }

Solution

1. Step 1: Identify regex modifiers in nginx

   Modifier ~* means case-insensitive regex match.

2. Step 2: Match syntax to case-insensitive regex

   location ~* "/images/" { } uses ~* correctly for case-insensitive regex.

3. Final Answer:

   location ~* "/images/" { } -> Option D

4. Quick Check:

   ~* = case-insensitive regex [OK]

Hint: Use ~* for case-insensitive regex location [OK]

Common Mistakes:

• Using ~ instead of ~* for case-insensitive match
• Confusing ^~ with regex modifiers
• Using = for regex match

3. Given this nginx config snippet, which location block will handle the request for URL /images/logo.png?

location = /images/logo.png { return 200 'Exact match'; }
location ^~ /images/ { return 200 'Prefix ^~ match'; }
location ~* \.(png|jpg)$ { return 200 'Regex match'; }
location / { return 200 'Default prefix match'; }

medium

A. Exact match location = /images/logo.png

B. Prefix match location ^~ /images/

C. Regex match location ~* \.(png|jpg)$

D. Default prefix match location /

Solution

1. Step 1: Check for exact match

   Request URL is /images/logo.png, which exactly matches = /images/logo.png.

2. Step 2: Confirm nginx uses exact match first

   nginx uses exact match location immediately without checking others.

3. Final Answer:

   Exact match location = /images/logo.png -> Option A

4. Quick Check:

   Exact match wins over prefix and regex [OK]

Hint: Exact match location = always wins first [OK]

Common Mistakes:

• Choosing ^~ prefix match over exact match
• Assuming regex match has higher priority
• Ignoring exact match syntax

4. You have this nginx config:

location /images/ {
  return 200 'Prefix match';
}
location ^~ /images/ {
  return 200 'Prefix ^~ match';
}

But requests to /images/photo.jpg return 'Prefix match' instead of 'Prefix ^~ match'. What is the likely cause?

medium

A. Two prefix locations with same path cause nginx to pick first declared

B. ^~ modifier is ignored if regex location exists

C. Regex location always has higher priority than ^~

D. Syntax error in ^~ location block

Solution

1. Step 1: Understand prefix location conflicts

   Two prefix locations with identical paths cause nginx to use the first declared one.

2. Step 2: Check config order

   The location /images/ block appears before location ^~ /images/, so nginx picks the first.

3. Final Answer:

   Two prefix locations with same path cause nginx to pick first declared -> Option A

4. Quick Check:

   First prefix wins if paths identical [OK]

Hint: Avoid duplicate prefix locations; nginx picks first declared [OK]

Common Mistakes:

• Assuming ^~ always overrides prefix regardless of order
• Thinking regex always beats ^~
• Believing syntax error causes this behavior

5. You want nginx to serve static files under /static/ using a prefix match but avoid regex checks for these URLs for performance. Which configuration achieves this best?

hard

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

B. location ~* /static/ { root /var/www/static; }

C. location ^~ /static/ { root /var/www/static; }

D. location = /static/ { root /var/www/static; }

Solution

1. Step 1: Understand ^~ modifier effect

   Using ^~ tells nginx to stop searching regex locations if this prefix matches.

2. Step 2: Apply to static files

   Setting location ^~ /static/ ensures static files served quickly without regex overhead.

3. Final Answer:

   location ^~ /static/ { root /var/www/static; } -> Option C

4. Quick Check:

   ^~ prefix disables regex checks [OK]

Hint: Use ^~ prefix to skip regex for performance [OK]

Common Mistakes:

• Using plain prefix allows regex checks
• Using regex location unnecessarily
• Using exact match = for directory prefix