Exact match (=) in Nginx - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the effect of the exact match (=) in this nginx location block?

Consider this nginx configuration snippet:

location = /about {
    return 200 'Exact match page';
}

What happens when a client requests /about?

Nginx

location = /about {
    return 200 'Exact match page';
}

A The server returns 'Exact match page' for any URI starting with '/about'.

B The server returns 'Exact match page' for any URI containing '/about' anywhere.

C The server returns 'Exact match page' for any URI ending with '/about'.

D The server returns 'Exact match page' only if the request URI is exactly '/about'.

💡 Hint

The '=' sign means the location matches the URI exactly, no more, no less.

The '=' modifier in nginx location means the block matches only if the request URI is exactly the same as the location string. No partial or prefix matches apply.

🧠 Conceptual

intermediate

How does nginx prioritize exact match (=) locations compared to prefix matches?

Given these location blocks:

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

Which location block will nginx use for a request to /test?

Nginx

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

A nginx uses the exact match location (= /test) before the prefix match (/test).

B nginx uses the prefix match (/test) before the exact match (= /test).

C nginx merges both locations and returns both responses.

D nginx returns a 404 error because of conflicting locations.

💡 Hint

Exact match locations have the highest priority in nginx.

nginx first checks for exact match locations (=). If found, it uses that block. Only if no exact match is found does it check prefix matches.

❓ Troubleshoot

advanced

Why does this nginx config not serve the exact match location as expected?

You have this config:

location = /home {
    proxy_pass http://backend1;
}
location /home {
    proxy_pass http://backend2;
}

Requests to /home are always served by backend2. Why?

Nginx

location = /home {
    proxy_pass http://backend1;
}
location /home {
    proxy_pass http://backend2;
}

A The request URI includes a trailing slash, so it does not exactly match '/home'.

B The exact match location is ignored because proxy_pass is missing a trailing slash.

C nginx does not support exact match locations with proxy_pass directives.

D The exact match location is overridden by the prefix location because of order in the config file.

💡 Hint

Check if the request URI exactly matches the location string, including trailing slashes.

If the client requests '/home/' (with trailing slash), it does not exactly match '= /home'. So nginx uses the prefix location '/home' instead.

✅ Best Practice

advanced

What is the recommended use of exact match (=) locations in nginx?

Which of these is the best practice when using exact match (=) locations in nginx?

A Avoid exact match locations because they cause nginx to reload the config on every request.

B Use exact match locations for specific URIs that need unique handling, like redirects or special responses.

C Use exact match locations for all static files to improve performance.

D Use exact match locations to match all URIs starting with a prefix.

💡 Hint

Exact match locations are precise and should be used sparingly for special cases.

Exact match locations are best for handling specific URIs that require unique behavior, such as redirects or custom responses. They are not for general prefix matching.

🔀 Workflow

expert

Order the steps nginx follows to select a location block for a request URI

Arrange the steps nginx uses to find the correct location block for a request URI, considering exact match (=), prefix, and regex locations.

A 1,3,2,4

B 2,1,3,4

C 1,2,3,4

D 3,1,2,4

💡 Hint

Exact matches have highest priority, then prefix, then regex.

nginx first checks exact match locations (=). If none, it finds the longest prefix match. Then it tests regex locations in order. If a regex matches, it uses that; otherwise, it uses the prefix match.

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