Rewrite flags (last, break, redirect, permanent) in Nginx - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What happens when using the 'last' rewrite flag?

Given this nginx rewrite rule:

rewrite ^/oldpath/(.*)$ /newpath/$1 last;

What is the effect of the 'last' flag in this context?

Nginx

rewrite ^/oldpath/(.*)$ /newpath/$1 last;

A Sends a 301 permanent redirect to the client with the rewritten URI.

B Stops processing current rewrite directives and restarts location search with the new URI.

C Stops processing rewrite directives and serves the rewritten URI immediately without further processing.

D Sends a 302 temporary redirect to the client with the rewritten URI.

💡 Hint

Think about how nginx handles URI rewriting and location matching after the rewrite.

The 'last' flag tells nginx to stop processing the current rewrite directives and restart the location search with the new URI. This means nginx will try to find a new location block matching the rewritten URI.

💻 Command Output

intermediate

What does the 'break' rewrite flag do in nginx?

Consider this rewrite rule:

rewrite ^/temp/(.*)$ /final/$1 break;

What is the behavior of the 'break' flag here?

Nginx

rewrite ^/temp/(.*)$ /final/$1 break;

A Sends a 301 redirect to the client with the rewritten URI.

B Restarts location search with the rewritten URI.

C Sends a 302 redirect to the client with the rewritten URI.

D Stops processing rewrite directives and continues processing the request within the current location using the rewritten URI.

💡 Hint

Think about whether nginx changes location blocks after this rewrite.

The 'break' flag stops processing further rewrite directives and continues handling the request in the current location block using the rewritten URI. It does not restart location matching.

💻 Command Output

advanced

What is the HTTP response when using the 'redirect' rewrite flag?

Given this rewrite rule:

rewrite ^/old/(.*)$ /new/$1 redirect;

What HTTP status code does nginx send to the client?

Nginx

rewrite ^/old/(.*)$ /new/$1 redirect;

A 302 Found (Temporary Redirect)

B 301 Moved Permanently

C 307 Temporary Redirect

D 200 OK with rewritten URI internally

💡 Hint

The 'redirect' flag sends a temporary redirect status code.

The 'redirect' flag sends a 302 Found status code to the client, instructing it to temporarily redirect to the new URI.

💻 Command Output

advanced

What HTTP status code does the 'permanent' rewrite flag send?

Analyze this rewrite rule:

rewrite ^/site/(.*)$ /website/$1 permanent;

What status code will nginx send to the client?

Nginx

rewrite ^/site/(.*)$ /website/$1 permanent;

A 303 See Other

B 302 Found

C 301 Moved Permanently

D 200 OK with internal rewrite

💡 Hint

The 'permanent' flag sends a permanent redirect status code.

The 'permanent' flag sends a 301 Moved Permanently status code to the client, indicating the resource has moved permanently.

❓ Troubleshoot

expert

Why does a rewrite with 'last' flag cause a redirect loop?

You have this nginx config snippet:

location /app/ {
  rewrite ^/app/(.*)$ /app/$1 last;
}

Requests to /app/page cause a redirect loop. What is the most likely reason?

Nginx

location /app/ {
  rewrite ^/app/(.*)$ /app/$1 last;
}

A The rewrite rewrites the URI to the same URI, causing nginx to restart location search endlessly.

B The 'last' flag is invalid here and causes nginx to crash.

C The rewrite rule syntax is incorrect and nginx ignores it.

D The 'break' flag should be used instead to avoid loops.

💡 Hint

Consider what happens when the rewritten URI matches the original location again.

The rewrite rule rewrites /app/page to /app/page again, and with the 'last' flag nginx restarts location matching. This causes an infinite loop of rewriting the same URI.

Practice

1. What does the last flag do in an nginx rewrite directive?

easy

A. Stops processing the current location and restarts the rewrite phase with the new URI

B. Sends a temporary redirect (HTTP 302) to the client

C. Stops processing the rewrite directives and continues with the current location

D. Sends a permanent redirect (HTTP 301) to the client

Solution

1. Step 1: Understand the last flag behavior

   The last flag tells nginx to stop processing current rewrite directives and restart the rewrite phase with the new URI.

2. Step 2: Compare with other flags

   Unlike break which stops rewriting internally, last restarts processing, and unlike redirect or permanent which send redirects, it does not send a client redirect.

3. Final Answer:

   Stops processing the current location and restarts the rewrite phase with the new URI -> Option A

4. Quick Check:

   last = restart rewrite phase [OK]

Hint: Remember: last restarts rewrite, break stops internally [OK]

Common Mistakes:

• Confusing last with break flag
• Thinking last sends a redirect
• Mixing last with permanent redirect

2. Which of the following is the correct syntax to perform a permanent redirect in nginx using the rewrite directive?

easy

A. rewrite ^/old$ /new break;

B. rewrite ^/old$ /new last;

C. rewrite ^/old$ /new permanent;

D. rewrite ^/old$ /new redirect;

Solution

1. Step 1: Identify the flag for permanent redirect

   The permanent flag sends an HTTP 301 status code indicating a permanent redirect.

2. Step 2: Check syntax correctness

   The syntax rewrite ^/old$ /new permanent; correctly applies the permanent redirect flag.

3. Final Answer:

   rewrite ^/old$ /new permanent; -> Option C

4. Quick Check:

   Permanent redirect uses permanent flag [OK]

Hint: Permanent redirect uses 'permanent' flag at end [OK]

Common Mistakes:

• Using 'last' or 'break' instead of 'permanent' for redirects
• Omitting the semicolon at the end
• Confusing 'redirect' with 'permanent'

3. Given the nginx configuration snippet:

location /test {
  rewrite ^/test/(.*)$ /new/$1 redirect;
}

What will happen when a client requests /test/page?

medium

A. The client will receive a 301 permanent redirect to /new/page

B. The rewrite will restart processing with the new URI /new/page

C. The request will be internally rewritten to /new/page without redirect

D. The client will receive a 302 temporary redirect to /new/page

Solution

1. Step 1: Understand the redirect flag

   The redirect flag sends an HTTP 302 temporary redirect to the client.

2. Step 2: Analyze the rewrite rule

   The rewrite matches /test/page and rewrites it to /new/page with a temporary redirect.

3. Final Answer:

   The client will receive a 302 temporary redirect to /new/page -> Option D

4. Quick Check:

   redirect = 302 temporary redirect [OK]

Hint: redirect flag means 302 temporary redirect [OK]

Common Mistakes:

• Confusing redirect with permanent
• Thinking redirect rewrites internally
• Assuming last or break flags here

4. You have this nginx rewrite rule:

rewrite ^/oldpath/(.*)$ /newpath/$1 last

But it causes a 500 Internal Server Error. What is the likely problem?

medium

A. Missing semicolon at the end of the rewrite directive

B. Using 'last' flag instead of 'break' causes infinite loop

C. The regex pattern is invalid

D. Rewrite directive must be inside a location block

Solution

1. Step 1: Check syntax of rewrite directive

   Every nginx directive must end with a semicolon. The given rewrite lacks a semicolon.

2. Step 2: Understand error cause

   Missing semicolon causes nginx to fail parsing config, leading to 500 error.

3. Final Answer:

   Missing semicolon at the end of the rewrite directive -> Option A

4. Quick Check:

   Missing semicolon = syntax error = 500 error [OK]

Hint: Always end rewrite directives with semicolon [OK]

Common Mistakes:

• Assuming last flag causes infinite loop
• Ignoring missing semicolon syntax errors
• Thinking regex pattern is wrong without checking

5. You want to rewrite URLs starting with /app to /app/index.html internally without redirecting the client, and stop further rewrite processing. Which rewrite directive and flag should you use?

hard

A. rewrite ^/app$ /app/index.html last;

B. rewrite ^/app$ /app/index.html break;

C. rewrite ^/app$ /app/index.html redirect;

D. rewrite ^/app$ /app/index.html permanent;

Solution

1. Step 1: Identify internal rewrite without client redirect

   The break flag stops rewrite processing and serves the rewritten URI internally without redirecting the client.

2. Step 2: Match requirement to flag

   Using break with the rewrite stops further rewrites and serves /app/index.html internally.

3. Final Answer:

   rewrite ^/app$ /app/index.html break; -> Option B

4. Quick Check:

   break = internal rewrite stop [OK]

Hint: Use break to rewrite internally and stop further rewrites [OK]

Common Mistakes:

• Using last which restarts rewrite phase
• Using redirect or permanent which send client redirects
• Not stopping rewrite processing causing unexpected behavior