Location blocks in Nginx - Step-by-Step Execution

Process Flow - Location blocks

Request comes in

↓

Check location blocks in order

↓

Match exact location?

Yes→Use exact block

No↓

Match prefix location?

Yes→Use longest prefix block

No↓

Match regex location?

Yes→Use first regex match

No↓

Use default location block

↓

Serve request with chosen block

Nginx checks location blocks in a specific order: exact match first, then prefix matches, then regex matches, and finally the default block if no match is found.

Execution Sample

Nginx

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

location /prefix {
  return 200 'Prefix match';
}

location ~ ^/regex {
  return 200 'Regex match';
}

This config defines three location blocks: exact match for /exact, prefix match for /prefix, and regex match for URLs starting with /regex.

Process Table

Step	Request URL	Check	Match Result	Chosen Location Block	Action
1	/exact	Check exact match location = /exact	Matched	/exact	Return 200 'Exact match'
2	/prefix/test	Check exact match location = /prefix/test	No match	N/A	Continue
3	/prefix/test	Check prefix location /prefix	Matched (longest prefix)	/prefix	Return 200 'Prefix match'
4	/regex123	Check exact match location = /regex123	No match	N/A	Continue
5	/regex123	Check prefix location /regex123	No match	N/A	Continue
6	/regex123	Check regex location ~ ^/regex	Matched	/regex	Return 200 'Regex match'
7	/other	Check exact match location = /other	No match	N/A	Continue
8	/other	Check prefix location /other	No match	N/A	Continue
9	/other	Check regex location ~ ^/regex	No match	N/A	Continue
10	/other	Use default location block	Default	/	Serve default content

💡 Request served by the first matching location block found in the order: exact, prefix, regex, or default.

Status Tracker

Variable	Start	After Step 1	After Step 3	After Step 6	After Step 10
Chosen Location Block	None	/exact	/prefix	/regex	/

Key Moments - 3 Insights

Why does nginx choose the exact match location block before prefix or regex?

Nginx prioritizes exact matches first as shown in execution_table row 1, so if an exact match exists, it uses that block immediately.

What happens if no exact or prefix location matches but a regex matches?

Nginx then uses the first regex location that matches, as seen in execution_table row 6 where regex match is chosen after no exact or prefix match.

Why is there a default location block used at the end?

If no exact, prefix, or regex matches are found, nginx falls back to the default location block to serve the request, as in execution_table row 10.

Visual Quiz - 3 Questions

Look at the execution table, which location block is chosen for the URL '/prefix/test'?

A /prefix

B /regex

C /exact

D /

💡 Hint

Check execution_table row 3 where prefix match is found for '/prefix/test'.

At which step does nginx decide to use the regex location block?

A Step 1

B Step 3

C Step 6

D Step 10

💡 Hint

See execution_table row 6 where regex match is confirmed.

If the exact location block for '/exact' was removed, what would happen for the URL '/exact'?

A Use regex location if matches

B Use prefix location if matches

C Use default location block

D Return 404 error

💡 Hint

Refer to concept_flow and execution_table logic: exact match missing leads to prefix match check.

Concept Snapshot

Nginx Location Blocks:
- Exact match (=) checked first
- Then longest prefix match (/)
- Then regex (~ or ~*) matches
- Finally default location (/)
Request served by first matching block found in this order.

Full Transcript

When nginx receives a request, it looks for a matching location block to decide how to serve it. It first checks if there is an exact match location block for the request URL. If found, it uses that block immediately. If not, it looks for prefix matches and chooses the longest matching prefix. If no prefix matches, it checks regex location blocks in order and uses the first regex that matches. If none of these match, it falls back to the default location block. This order ensures nginx serves requests efficiently and predictably.