Location blocks in Nginx - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a location block in nginx?

A location block defines how nginx should respond to requests for specific URLs or URL patterns.

beginner

How do you write a simple location block to match the URL /images/?

Use location /images/ { ... } to match all requests starting with /images/.

intermediate

What is the difference between location = /path and location /path?

location = /path matches the exact URL /path only, while location /path matches any URL starting with /path.

intermediate

What does the ^~ modifier do in a location block?

The ^~ modifier tells nginx to stop searching if this prefix match is found and use this block immediately.

advanced

How does nginx choose which location block to use when multiple match?

Nginx first looks for exact matches, then prefix matches with ^~, then regex matches, and finally the longest prefix match.

Which location block matches only the exact URL /about?

A location /about { ... }

B location = /about { ... }

C location ^~ /about { ... }

D location ~ /about { ... }

The '=' modifier matches the exact URL only.

What does the ^~ modifier do in a location block?

A Matches regex patterns

B Ignores this location block

C Matches exact URL only

D Stops searching on prefix match

The '^~' modifier tells nginx to stop searching if this prefix matches.

Which location block matches URLs starting with /api/?

A location = /api/ { ... }

B location ~ /api/ { ... }

C location /api/ { ... }

D location ^~ /api/ { ... }

A prefix match without modifiers matches URLs starting with the given path.

If multiple location blocks match, which one does nginx prefer first?

A Exact match

B Regex match

C Longest prefix match

D First defined block

Nginx prefers exact matches before other types.

How do you define a location block that matches URLs using a regex?

A location ~ /pattern/ { ... }

B location /regex/ { ... }

C location = /regex/ { ... }

D location ^~ /pattern/ { ... }

The '~' modifier defines a regex match in location blocks.

Explain how nginx chooses which location block to use when multiple blocks match a request URL.

Think about the order nginx checks location blocks.

Describe the difference between prefix matches and regex matches in nginx location blocks.

Consider how nginx processes URL patterns.

Practice

1. What is the main purpose of a location block in an nginx configuration?

easy

A. To specify the server's hostname

B. To set the server's IP address

C. To define how nginx handles requests for specific URL paths

D. To configure the database connection

Solution

1. Step 1: Understand the role of location blocks

   Location blocks in nginx specify rules for handling requests based on URL paths.

2. Step 2: Compare options with location block purpose

   Only To define how nginx handles requests for specific URL paths correctly describes this purpose; others relate to different server settings.

3. Final Answer:

   To define how nginx handles requests for specific URL paths -> Option C

4. Quick Check:

   Location blocks control URL handling = D [OK]

Hint: Location blocks match URLs to control request handling [OK]

Common Mistakes:

• Confusing location blocks with server settings
• Thinking location blocks set server IP or hostname
• Mixing location blocks with database configs

2. Which of the following is the correct syntax to define a location block that matches the exact URL /about?

easy

A. location /about { }

B. location ~ /about { }

C. location ^~ /about { }

D. location = /about { }

Solution

1. Step 1: Understand location modifiers

   The = modifier matches the exact URL path.

2. Step 2: Match syntax to exact URL

   location = /about { } uses = /about which matches exactly '/about'. Others match prefixes or regex.

3. Final Answer:

   location = /about { } -> Option D

4. Quick Check:

   Exact match uses '=' modifier = C [OK]

Hint: Use '=' for exact URL match in location block [OK]

Common Mistakes:

• Using no modifier for exact match
• Confusing regex (~) with exact match
• Using ^~ which is prefix, not exact

3. Given this nginx config snippet:

location /images/ {
  root /data;
}

What is the full file path nginx will serve for a request to /images/pic.jpg?

medium

A. /data/pic.jpg

B. /data/images/pic.jpg

C. /images/pic.jpg

D. /data/images/

Solution

1. Step 1: Understand root directive with location

   The root directive appends the part of the URI after the location prefix to the root path.

2. Step 2: Combine root and URI

   Location prefix is /images/, request URI is /images/pic.jpg, so the part after prefix is pic.jpg. Root is /data, so full path is /data/pic.jpg.

3. Final Answer:

   /data/pic.jpg -> Option A

4. Quick Check:

   root + URI after location prefix = /data/pic.jpg [OK]

Hint: root + URI after location prefix = file path served [OK]

Common Mistakes:

• Assuming root combines with full URI
• Using full URI instead of URI after location prefix
• Confusing alias with root behavior

4. Identify the error in this nginx location block:

location /static/ {
  alias /var/www/static;
}

medium

A. Missing trailing slash in alias path

B. alias should be root here

C. location path should not end with slash

D. No error, configuration is correct

Solution

1. Step 1: Understand alias usage

   When using alias with a location ending with a slash, the alias path must also end with a slash.

2. Step 2: Check alias path

   Alias path /var/www/static lacks trailing slash, causing incorrect file path resolution.

3. Final Answer:

   Missing trailing slash in alias path -> Option A

4. Quick Check:

   Alias path must end with '/' if location ends with '/' = B [OK]

Hint: Alias path needs trailing slash if location ends with slash [OK]

Common Mistakes:

• Using root instead of alias incorrectly
• Omitting trailing slash on alias path
• Thinking location path cannot end with slash

5. You want nginx to serve static files from /var/www/app/static when users request URLs starting with /static/, but you want to avoid duplicating the /static/ part in the file path. Which location block correctly achieves this?

hard

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

B. location /static/ { alias /var/www/app/static/; }

C. location /static/ { alias /var/www/app/static; }

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

Solution

1. Step 1: Understand alias vs root behavior

   Alias replaces the location prefix with the alias path exactly, avoiding duplication.

2. Step 2: Check trailing slashes for alias

   Alias path must end with a slash to match location ending with slash, ensuring correct path mapping.

3. Step 3: Evaluate options

   location /static/ { alias /var/www/app/static/; } uses alias with trailing slash, correctly mapping /static/file to /var/www/app/static/file. Others either duplicate path or miss slash.

4. Final Answer:

   location /static/ { alias /var/www/app/static/; } -> Option B

5. Quick Check:

   Alias with trailing slash avoids duplication = A [OK]

Hint: Use alias with trailing slash to avoid path duplication [OK]

Common Mistakes:

• Using root causing duplicated /static/ in path
• Omitting trailing slash on alias path
• Confusing alias and root usage