Exact match (=) in Nginx - Step-by-Step Execution

Process Flow - Exact match (=)

Request URL Received

↓

Check location blocks

↓

Is there a location with = prefix?

No→Use other location matching

Yes↓

Compare request URL exactly with location path

↓

Exact match found?

No→Try other location blocks

Yes↓

Serve request using exact match location

↓

END

Nginx checks if a location block with '=' prefix exactly matches the request URL path and serves it immediately if found.

Execution Sample

Nginx

location = /exact {
    return 200 'Exact match!';
}

This config serves requests exactly matching '/exact' with a 200 response and message.

Process Table

Step	Request URL	Location Checked	Match Type	Match Result	Action
1	/exact	location = /exact	Exact match (=)	Match	Serve with 200 'Exact match!'
2	/exact/more	location = /exact	Exact match (=)	No match	Try other locations
3	/exact/more	location /exact	Prefix match	Match	Serve with prefix location
4	/other	location = /exact	Exact match (=)	No match	Try other locations
5	/other	location /	Prefix match	Match	Serve with default location

💡 Exact match location serves only when request URL exactly equals location path.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5
Request URL	N/A	/exact	/exact/more	/exact/more	/other	/other
Location Matched	None	= /exact	None	/exact	None	/

Key Moments - 2 Insights

Why does the exact match location not serve '/exact/more'?

Because the exact match (=) requires the request URL to be exactly '/exact'. '/exact/more' is longer, so it does not match the exact location (see execution_table rows 2 and 3).

What happens if no exact match location is found?

Nginx tries other location blocks like prefix matches until it finds one that matches (see execution_table rows 4 and 5).

Visual Quiz - 3 Questions

Look at the execution table, what location serves the request URL '/exact'?

A location /exact

B location /

C location = /exact

D No location serves it

💡 Hint

Check step 1 in the execution_table where '/exact' matches location = /exact exactly.

At which step does the request URL '/exact/more' get served by a prefix location?

A Step 3

B Step 2

C Step 1

D Step 5

💡 Hint

Look at step 3 in execution_table where '/exact/more' matches location /exact as prefix.

If the request URL is '/other', which location serves it according to the table?

A location = /exact

B location /

C location /exact

D No location

💡 Hint

See steps 4 and 5 in execution_table where '/other' falls back to location /.

Concept Snapshot

Exact match (=) in nginx location blocks means the request URL must match the location path exactly.
If matched, nginx serves that location immediately.
If no exact match, nginx tries prefix or regex locations.
Use '=' prefix for exact match locations.
Example: location = /path { ... }

Full Transcript

When nginx receives a request, it checks location blocks to find the best match. If a location block uses the '=' prefix, nginx compares the request URL exactly to that location's path. If they match exactly, nginx serves the request using that location immediately. If not, nginx continues checking other locations like prefix or regex matches. For example, a location defined as 'location = /exact' will only serve requests to '/exact' and not '/exact/more'. This ensures precise control over which requests are handled by which location blocks.

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