Conditional redirects with if in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to redirect all HTTP requests to HTTPS.

Nginx

if ($scheme = [1]) {
    return 301 https://$host$request_uri;
}

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

Ahttps

Bhttp

Cftp

Dws

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'https' in the condition causes a redirect loop.

Using unsupported schemes like 'ftp' or 'ws'.

We check if the scheme is 'http' to redirect to HTTPS.

2fill in blank

medium

Complete the code to redirect users from example.com to www.example.com.

Nginx

if ($host = [1]) {
    return 301 https://www.example.com$request_uri;
}

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

Aexample.com

Bwww.example.com

Cexample.net

Dwww.example.net

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for 'www.example.com' instead of 'example.com'.

Using a different domain like 'example.net'.

The condition checks if the host is 'example.com' to redirect to 'www.example.com'.

3fill in blank

hard

Fix the error in the code to redirect mobile users to m.example.com.

Nginx

if ($http_user_agent ~* [1]) {
    return 302 https://m.example.com$request_uri;
}

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

A"Mobile"

B/Mobile/

CMobile

D/mobile/

Attempts:

3 left

💡 Hint

Common Mistakes

Adding quotes or slashes around the regex pattern.

Using case-sensitive match (~ instead of ~*).

The pattern should be a plain string without quotes or slashes for the regex match.

4fill in blank

hard

Fill both blanks to redirect requests with query parameter 'ref=old' to '/newpage'.

Nginx

if ($arg_[1] = [2]) {
    return 301 /newpage;
}

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

Aref

Bold

Cnew

Dpage

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect parameter names.

Checking for wrong values like 'new' instead of 'old'.

$arg_ref accesses the 'ref' query parameter, and we check if it equals 'old' to redirect.

5fill in blank

hard

Fill all three blanks to redirect requests from 'example.org' with user agent containing 'Bot' to '/botpage'.

Nginx

if ($host = [1]) {
    if ($http_user_agent ~* [2]) {
        return 302 [3];
    }
}

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

Aexample.org

BBot

C/botpage

D/userpage

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the host or user agent values.

Using wrong redirect URLs.

First check if host is 'example.org', then if user agent contains 'Bot', redirect to '/botpage'.

Practice

1. What does the if directive do in an nginx configuration for conditional redirects?

easy

A. It logs all user requests to a file.

B. It checks a condition and performs an action like redirect if true.

C. It restarts nginx automatically.

D. It permanently disables the server.

Solution

1. Step 1: Understand the role of if in nginx

   The if directive evaluates a condition inside the server or location block.

2. Step 2: Recognize its use for redirects

   If the condition is true, nginx can perform actions like return to redirect users.

3. Final Answer:

   It checks a condition and performs an action like redirect if true. -> Option B

4. Quick Check:

   if checks condition for redirect [OK]

Hint: Remember: if tests, return redirects [OK]

Common Mistakes:

• Thinking if restarts nginx
• Confusing if with logging
• Assuming if disables server

2. Which of the following is the correct syntax to redirect all requests from /old to /new using if in nginx?

easy

A. if ($request_uri == "/old") return 301 /new;

B. if $request_uri == "/old" { return 301 /new; }

C. if ($request_uri = "/old") { return 301 /new; }

D. if $request_uri = "/old" return 301 /new;

Solution

1. Step 1: Check correct if syntax in nginx

   nginx requires parentheses around the condition and uses a single equals sign for string comparison.

2. Step 2: Confirm the block and return statement

   The condition must be inside parentheses, followed by braces with the return directive inside.

3. Final Answer:

   if ($request_uri = "/old") { return 301 /new; } -> Option C

4. Quick Check:

   Parentheses and braces with single = [OK]

Hint: Use parentheses and single = inside if [OK]

Common Mistakes:

• Using double == instead of single =
• Omitting parentheses around condition
• Missing braces around return

3. Given this nginx snippet:

server {
  listen 80;
  server_name example.com;
  location / {
    if ($http_user_agent ~* "Mobile") {
      return 302 /mobile;
    }
  }
}

What happens when a user with user agent "Mozilla Mobile" visits http://example.com/?

medium

A. They are redirected to /mobile with a 302 status.

B. They see the normal homepage without redirect.

C. They get a 404 error.

D. The server crashes due to syntax error.

Solution

1. Step 1: Understand the if condition with regex

   The condition checks if the user agent contains "Mobile" ignoring case.

2. Step 2: Apply the redirect action

   Since "Mozilla Mobile" matches, nginx returns a 302 redirect to /mobile.

3. Final Answer:

   They are redirected to /mobile with a 302 status. -> Option A

4. Quick Check:

   User agent matches regex, triggers redirect [OK]

Hint: Regex ~* means case-insensitive match [OK]

Common Mistakes:

• Ignoring case sensitivity in regex
• Assuming no redirect happens
• Thinking syntax error occurs

4. Identify the error in this nginx config snippet for redirecting /old to /new:

if $request_uri = "/old" {
  return 301 /new;
}

medium

A. Missing parentheses around the condition in if.

B. Using double equals instead of single equals.

C. Missing semicolon after if statement.

D. Incorrect return status code.

Solution

1. Step 1: Check if syntax requirements

   nginx requires the condition inside parentheses after if.

2. Step 2: Verify the given snippet

   The snippet lacks parentheses around $request_uri = "/old", causing syntax error.

3. Final Answer:

   Missing parentheses around the condition in if. -> Option A

4. Quick Check:

   if needs parentheses [OK]

Hint: Always wrap if conditions in parentheses [OK]

Common Mistakes:

• Forgetting parentheses in if
• Confusing single and double equals
• Thinking semicolon needed after if

5. You want to redirect users accessing /old only if they come from the domain example.com. Which nginx config snippet correctly does this using if?

hard

A. if ($request_uri = "/old" && $http_referer ~* "example.com") { return 301 /new; }

B. if ($request_uri = "/old") { return 301 /new if ($http_referer ~* "example.com"); }

C. if ($request_uri = "/old" || $http_referer ~* "example.com") { return 301 /new; }

D. if ($request_uri = "/old") { if ($http_referer ~* "example.com") { return 301 /new; } }

Solution

1. Step 1: Understand nginx if limitations

   nginx does not support combining conditions with && inside a single if.

2. Step 2: Use nested if for multiple conditions

   Nested if blocks allow checking one condition inside another.

3. Step 3: Analyze options

   if ($request_uri = "/old") { if ($http_referer ~* "example.com") { return 301 /new; } } uses nested if correctly; others use unsupported syntax or wrong logic.

4. Final Answer:

   if ($request_uri = "/old") { if ($http_referer ~* "example.com") { return 301 /new; } } -> Option D

5. Quick Check:

   Nested if for multiple conditions [OK]

Hint: Use nested if for multiple conditions in nginx [OK]

Common Mistakes:

• Trying to use && inside one if
• Using || instead of && for AND logic
• Placing return incorrectly