Regex match (~, ~*) in Nginx - Mini Project: Build & Apply

Using Regex Match (~, ~*) in Nginx Configuration

📖 Scenario: You are setting up an Nginx web server. You want to control access to certain URLs using regular expressions.Specifically, you want to allow access only to URLs that start with /images/ and end with .jpg or .png.

🎯 Goal: Build an Nginx configuration snippet that uses regex match operators ~ and ~* to match URLs case-sensitively and case-insensitively.You will create a location block that matches URLs ending with .jpg or .png case-sensitively, and another location block that matches URLs ending with .JPG or .PNG case-insensitively.

📋 What You'll Learn

Create a location block using ~ for case-sensitive regex matching

Create a location block using ~* for case-insensitive regex matching

Use regex to match URLs starting with /images/ and ending with .jpg or .png

Add a simple return 200 directive inside each location block to confirm matching

💡 Why This Matters

🌍 Real World

Web servers often need to route or restrict access based on URL patterns. Regex matching in Nginx helps achieve flexible and powerful URL control.

💼 Career

Understanding regex matching in Nginx is essential for DevOps engineers and system administrators managing web servers and application deployments.

1

Create the base Nginx server block

Write an Nginx server block with listen 80; and an empty body. Name the server block server {}.

Nginx

# Write the Nginx server block with listen 80
# Your code here

Hint

Start by writing server { and inside it add listen 80;.

2

Add a case-sensitive regex location block

Inside the server block, add a location block using the ~ operator to match URLs starting with /images/ and ending with .jpg or .png (case-sensitive). Inside it, add return 200;.

Nginx

server {
    listen 80;
    # Add a location block with ~ regex match for .jpg or .png files
    # Your code here
}

Hint

Use location ~ ^/images/.*\.(jpg|png)$ to match URLs case-sensitively.

3

Add a case-insensitive regex location block

Below the previous location block, add another location block using the ~* operator to match URLs starting with /images/ and ending with .JPG or .PNG (case-insensitive). Inside it, add return 200;.

Nginx

server {
    listen 80;
    location ~ ^/images/.*\.(jpg|png)$ {
        return 200;
    }
    # Add a location block with ~* regex match for .JPG or .PNG files
    # Your code here
}

Hint

Use location ~* ^/images/.*\.(jpg|png)$ for case-insensitive matching.

4

Test and output the final Nginx configuration

Print the entire Nginx configuration code you wrote so far.

Nginx

# Print the full Nginx configuration
# Your code here

Hint

Print the full configuration exactly as written.

Practice

1. What does the ~ operator mean in an nginx location block?

easy

A. It matches any request regardless of URL.

B. It performs a case-insensitive regular expression match.

C. It performs a case-sensitive regular expression match.

D. It matches the exact string only.

Solution

1. Step 1: Understand nginx regex operators

   The ~ operator in nginx is used for regex matching that is case-sensitive.

2. Step 2: Differentiate from ~*

   The ~* operator is for case-insensitive regex matching, so it is different from ~.

3. Final Answer:

   It performs a case-sensitive regular expression match. -> Option C

4. Quick Check:

   ~ = case-sensitive regex match [OK]

Hint: Remember: ~ is case-sensitive, ~* is case-insensitive [OK]

Common Mistakes:

• Confusing ~ with ~* for case sensitivity
• Thinking ~ matches exact strings only
• Assuming ~ matches all requests

2. Which of the following is the correct syntax to match URLs case-insensitively using regex in nginx?

easy

A. location ~* /images/ { }

B. location = /images/ { }

C. location ~ /images/ { }

D. location /images/ { }

Solution

1. Step 1: Identify case-insensitive regex syntax

   In nginx, ~* is used for case-insensitive regex matching.

2. Step 2: Check other options

   ~ is case-sensitive, = is exact match, and no operator means prefix match.

3. Final Answer:

   location ~* /images/ { } -> Option A

4. Quick Check:

   Case-insensitive regex = ~* [OK]

Hint: Use ~* for case-insensitive regex in nginx location [OK]

Common Mistakes:

• Using ~ instead of ~* for case-insensitive matching
• Confusing exact match (=) with regex
• Omitting regex operator for regex matching

3. Given this nginx config snippet:

location ~* \.jpg$ {
  return 200 'Image file matched';
}

What will be the response for a request to /photos/Sunset.JPG?

medium

A. 404 Not Found

B. 500 Internal Server Error

C. 200 with empty body

D. 200 with 'Image file matched'

Solution

1. Step 1: Analyze the regex and operator

   The ~* operator means case-insensitive regex match. The regex \.jpg$ matches strings ending with '.jpg' ignoring case.

2. Step 2: Check the request URL

   The request is /photos/Sunset.JPG, which ends with '.JPG' (uppercase). Case-insensitive match succeeds.

3. Final Answer:

   200 with 'Image file matched' -> Option D

4. Quick Check:

   Case-insensitive regex matches .JPG [OK]

Hint: ~* ignores case, so .JPG matches \.jpg$ regex [OK]

Common Mistakes:

• Assuming regex is case-sensitive with ~*
• Ignoring the $ end anchor in regex
• Confusing response codes returned

4. Identify the error in this nginx location block:

location ~* /images/(.*\.png$ {
  proxy_pass http://backend;
}

medium

A. Missing closing parenthesis in regex

B. Using ~* instead of ~ for case-sensitive match

C. proxy_pass URL is invalid

D. location block missing curly braces

Solution

1. Step 1: Check regex syntax

   The regex /images/(.*\.png$ has an opening parenthesis but no closing parenthesis.

2. Step 2: Validate other parts

   The ~* operator is valid for case-insensitive match, proxy_pass URL looks valid, and curly braces are present.

3. Final Answer:

   Missing closing parenthesis in regex -> Option A

4. Quick Check:

   Regex parentheses must be balanced [OK]

Hint: Count parentheses in regex to avoid syntax errors [OK]

Common Mistakes:

• Forgetting to close parentheses in regex
• Confusing ~ and ~* usage
• Ignoring syntax errors in regex patterns

5. You want to serve all URLs ending with .css or .CSS using a regex match in nginx. Which location block correctly matches both cases efficiently?

hard

A. location ~ \.css$ { }

B. location ~* \.css$ { }

C. location ~ \.css$|\.CSS$ { }

D. location ~* \.css$|\.CSS$ { }

Solution

1. Step 1: Understand case-insensitive matching

   Using ~* makes the regex case-insensitive, so it matches both '.css' and '.CSS'.

2. Step 2: Evaluate other options

   location ~ \.css$ { } uses case-sensitive ~, so it misses '.CSS'. Options C and D have incorrect regex syntax with unescaped pipes and redundant patterns.

3. Final Answer:

   location ~* \.css$ { } -> Option B

4. Quick Check:

   Use ~* for simple case-insensitive regex [OK]

Hint: Use ~* with simple regex to match case-insensitive extensions [OK]

Common Mistakes:

• Using ~ and missing uppercase matches
• Trying to match cases with complex regex instead of ~*
• Incorrect escaping of regex special characters