Prefix match in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to match all requests starting with /images/.

Nginx

location [1] /images/ { }

Drag options to blanks, or click blank then click option'

A^~

B~

C/

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using ~ which is for regex match.

Using = which is for exact match.

Using / which is default prefix but without stopping further regex checks.

The prefix match in nginx uses the ^~ modifier to match the beginning of the URI.

2fill in blank

medium

Complete the code to match requests exactly equal to /about.

Nginx

location [1] /about { }

Drag options to blanks, or click blank then click option'

A~

B^~

C/

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using / which matches prefix, not exact.

Using ^~ which matches prefix but not exact.

Using ~ which is for regex.

The = modifier matches the exact URI in nginx location blocks.

3fill in blank

hard

Fix the error in this location block to match all URIs starting with /api/ without regex.

Nginx

location [1] /api/ { }

Drag options to blanks, or click blank then click option'

A/

B=

C^~

D~

Attempts:

3 left

💡 Hint

Common Mistakes

Using ~ which treats /api/ as regex.

Using = which matches exact URI only.

Using / which allows regex locations to override.

Using ^~ ensures nginx matches the prefix /api/ and stops searching further regex locations.

4fill in blank

hard

Fill both blanks to create a location block that matches URIs starting with /static/ and disables regex checks.

Nginx

location [1] [2] { }

Drag options to blanks, or click blank then click option'

A^~

B/static/

C~

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using ~ which is regex and does not disable further checks.

Using = which matches exact URI only.

Swapping the order of modifier and URI.

The ^~ modifier with the prefix /static/ matches all URIs starting with /static/ and disables regex checks.

5fill in blank

hard

Fill all three blanks to create a location block that matches URIs starting with /docs/, disables regex, and sets root to /var/www/docs.

Nginx

location [1] [2] {
    root [3];
}

Drag options to blanks, or click blank then click option'

A^~

B/docs/

C/var/www/docs

D~

Attempts:

3 left

💡 Hint

Common Mistakes

Using ~ which is regex and does not disable further checks.

Using wrong root path.

Swapping modifier and URI.

Using ^~ with /docs/ disables regex checks and root sets the directory for this location.

Practice

1. What does prefix match in nginx do when routing requests?

easy

A. It matches requests based on the start of the URL path.

B. It matches requests only if the full URL matches exactly.

C. It matches requests based on the file extension.

D. It matches requests randomly to any location block.

Solution

1. Step 1: Understand prefix match concept

   Prefix match means nginx checks if the URL path starts with a specific string.

2. Step 2: Compare with other matching types

   Exact match requires full URL match, file extension match is unrelated, random match is invalid.

3. Final Answer:

   It matches requests based on the start of the URL path. -> Option A

4. Quick Check:

   Prefix match = start of URL path [OK]

Hint: Prefix match checks URL start, not full or random [OK]

Common Mistakes:

• Confusing prefix match with exact match
• Thinking prefix match checks file extensions
• Assuming prefix match is random

2. Which of the following is the correct syntax for a prefix match location in nginx?

easy

A. location = /images/ { }

B. location ^~ /images/ { }

C. location /images/ { }

D. location ~ /images/ { }

Solution

1. Step 1: Identify prefix match syntax

   Prefix match uses plain location /prefix/ { } without modifiers.

2. Step 2: Understand other modifiers

   = is exact match, ^~ is prefix but with higher priority, ~ is regex match.

3. Final Answer:

   location /images/ { } -> Option C

4. Quick Check:

   Plain location = prefix match [OK]

Hint: Plain location block means prefix match [OK]

Common Mistakes:

• Using = or ^~ modifiers for simple prefix match
• Confusing regex (~) with prefix match
• Missing trailing slash in prefix

3. Given this nginx config snippet:

location /app/ {
  proxy_pass http://backend1;
}
location /app/api/ {
  proxy_pass http://backend2;
}

Which backend will handle a request to /app/api/users?

medium

A. Both backends in round-robin

B. http://backend2

C. No backend, 404 error

D. http://backend1

Solution

1. Step 1: Understand prefix match selection

   nginx selects the location with the longest matching prefix for plain prefix locations (no modifiers).

2. Step 2: Compare prefixes

   Both /app/ (length 5) and /app/api/ (length 9) match /app/api/users, but /app/api/ is longer, so it wins.

3. Final Answer:

   http://backend2 -> Option B

4. Quick Check:

   Longest prefix wins [OK]

Hint: Longest matching prefix wins [OK]

Common Mistakes:

• Thinking config order (first match) wins instead of longest prefix
• Thinking regex or exact match applies here
• Believing nginx load balances both backends

4. You wrote this nginx config:

location /static {
  root /var/www/html;
}

Requests to /static/css/style.css return 404. What is the likely error?

medium

A. root directive path is incorrect

B. location block should use = modifier

C. Missing trailing slash in location prefix

D. proxy_pass is missing

Solution

1. Step 1: Understand root directive behavior

   root appends the full request URI (/static/css/style.css) to /var/www/html, looking for /var/www/html/static/css/style.css.

2. Step 2: Identify likely cause

   If static files are at /var/www/html/css/style.css (without static/), root path doesn't strip prefix, causing 404. (Use alias /var/www/html; to strip.)

3. Final Answer:

   root directive path is incorrect -> Option A

4. Quick Check:

   root + full URI (no prefix strip) [OK]

Hint: root appends full URI; alias strips prefix [OK]

Common Mistakes:

• Confusing root (full URI) with alias (strips prefix)
• Thinking trailing slash strips prefix for root
• Adding unnecessary modifiers like =

5. You want nginx to route all requests starting with /api/ to http://backend_api and all others to http://backend_web, ensuring the /api/ prefix has priority even if regex locations follow. Which config correctly uses prefix match for this?

hard

A. location ~ /api/ {
proxy_pass http://backend_api;
}
location / {
proxy_pass http://backend_web;
}

B. location /api/ {
proxy_pass http://backend_api;
}
location / {
proxy_pass http://backend_web;
}

C. location = /api/ {
proxy_pass http://backend_api;
}
location / {
proxy_pass http://backend_web;
}

D. location ^~ /api/ {
proxy_pass http://backend_api;
}
location / {
proxy_pass http://backend_web;
}

Solution

1. Step 1: Use ^~ for prefix priority

   The ^~ modifier tells nginx to stop searching if prefix matches, ensuring /api/ routes to backend_api even over later regex.

2. Step 2: Default location for others

   The plain location / { } catches all other requests to backend_web.

3. Final Answer:

   location ^~ /api/ { proxy_pass http://backend_api; } location / { proxy_pass http://backend_web; } -> Option D

4. Quick Check:

   ^~ prefix match for priority routing [OK]

Hint: Use ^~ to prioritize prefix match over regex [OK]

Common Mistakes:

• Not using ^~ causes regex or exact match to override
• Using = modifier limits to exact /api/ only
• Using ~ makes it regex, not prefix match