Debug mode in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enable debug logging in nginx configuration.

Nginx

error_log /var/log/nginx/error.log [1];

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

Aerror

Binfo

Cwarn

Ddebug

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'error' level which shows only errors, not debug info.

Using 'info' which is less detailed than debug.

Setting the error_log level to debug enables detailed debug logging in nginx.

2fill in blank

medium

Complete the code to enable debug mode for a specific nginx location block.

Nginx

location /test {
    [1] on;
}

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

Adebug_connection

Berror_log

Cproxy_debug

Ddebug

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'debug' which is not a valid directive here.

Using 'proxy_debug' which does not exist.

The debug_connection directive enables debug logging for connections from specific IPs or all if set to 'all'.

3fill in blank

hard

Fix the error in the nginx debug log directive to correctly enable debug logging.

Nginx

error_log /var/log/nginx/debug.log [1] debug;

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

Awarn

Berror

Coff

Dinfo

Attempts:

3 left

💡 Hint

Common Mistakes

Leaving a log level before 'debug' causes syntax errors.

Using 'error' or 'warn' instead of 'off'.

The off keyword disables the default log level, allowing the explicit debug level to work correctly.

4fill in blank

hard

Fill both blanks to configure nginx to log debug messages only for connections from localhost.

Nginx

error_log /var/log/nginx/error.log [1];
debug_connection [2];

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

Adebug

Binfo

Call

D127.0.0.1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'all' in debug_connection logs debug for all connections.

Using 'info' instead of 'debug' for error_log.

Set error_log level to debug and debug_connection to 127.0.0.1 to enable debug logs only for localhost connections.

5fill in blank

hard

Fill all three blanks to create a map that enables debug logging only for requests from a specific IP.

Nginx

map $remote_addr $debug_mode {
    default [1];
    [2] [3];
}

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

Aoff

B192.168.1.100

Con

D127.0.0.1

Attempts:

3 left

💡 Hint

Common Mistakes

Setting default to 'on' enables debug for all IPs.

Mixing IP addresses or using 'all' instead of a specific IP.

This map sets debug_mode to off by default, but turns it on for the IP 192.168.1.100.

Practice

1. What does enabling debug mode in nginx do?

easy

A. Shows detailed logs to help find problems

B. Stops nginx from running

C. Deletes all log files

D. Automatically fixes errors

Solution

1. Step 1: Understand debug mode purpose

   Debug mode is designed to provide detailed information about what nginx is doing internally.

2. Step 2: Identify effect of enabling debug mode

   It shows detailed logs that help find and fix problems in nginx configuration or operation.

3. Final Answer:

   Shows detailed logs to help find problems -> Option A

4. Quick Check:

   Debug mode = detailed logs [OK]

Hint: Debug mode means detailed logs for troubleshooting [OK]

Common Mistakes:

• Thinking debug mode stops nginx
• Believing debug mode deletes logs
• Assuming debug mode auto-fixes errors

2. Which is the correct syntax to enable debug mode in nginx's error log?

easy

A. error_log debug /var/log/nginx/error.log;

B. error_log /var/log/nginx/error.log info;

C. error_log /var/log/nginx/error.log debug;

D. error_log /var/log/nginx/error.log off;

Solution

1. Step 1: Recall error_log syntax

   The correct syntax is: error_log <file_path> <level>; where level can be debug, info, etc.

2. Step 2: Identify correct option

   error_log /var/log/nginx/error.log debug; uses correct order: file path first, then debug level.

3. Final Answer:

   error_log /var/log/nginx/error.log debug; -> Option C

4. Quick Check:

   error_log file_path debug; = error_log /var/log/nginx/error.log debug; [OK]

Hint: error_log path then level debug; is correct syntax [OK]

Common Mistakes:

• Swapping file path and level order
• Using info instead of debug for debug mode
• Setting level to off disables logging

3. Given this nginx config snippet:

error_log /var/log/nginx/error.log debug;
server {
  listen 80;
  server_name example.com;
}

What will happen when nginx receives a request?

medium

A. Detailed debug logs will be written to /var/log/nginx/error.log

B. No logs will be created

C. Only error messages will be logged

D. Nginx will refuse connections

Solution

1. Step 1: Analyze error_log level

   The error_log is set to debug level, which logs detailed info about requests.

2. Step 2: Understand effect on request handling

   When nginx receives a request, it logs detailed debug info to the specified file.

3. Final Answer:

   Detailed debug logs will be written to /var/log/nginx/error.log -> Option A

4. Quick Check:

   debug level logs detailed info [OK]

Hint: debug level logs detailed info on requests [OK]

Common Mistakes:

• Thinking debug disables logging
• Assuming only errors are logged
• Believing nginx refuses connections with debug

4. You set error_log /var/log/nginx/error.log debug; but see no debug logs. What is a likely cause?

medium

A. Debug mode disables logging

B. Nginx was not reloaded after config change

C. The log file path is missing

D. The debug level is misspelled

Solution

1. Step 1: Check if config changes are active

   After changing nginx config, you must reload nginx to apply changes.

2. Step 2: Identify why no debug logs appear

   If nginx is not reloaded, it uses old config without debug logging.

3. Final Answer:

   Nginx was not reloaded after config change -> Option B

4. Quick Check:

   Reload nginx after config change [OK]

Hint: Reload nginx after config changes to activate debug [OK]

Common Mistakes:

• Forgetting to reload nginx
• Thinking debug disables logs
• Misspelling debug level

5. You want to enable debug mode only temporarily to avoid large log files. Which is the best approach?

hard

A. Delete log files manually to reduce size

B. Permanently set debug mode in nginx.conf

C. Disable logging completely during debugging

D. Set error_log /var/log/nginx/error.log debug;, reload nginx, then revert after debugging

Solution

1. Step 1: Understand temporary debug enabling

   Temporarily enable debug by changing error_log level and reloading nginx.

2. Step 2: Revert changes after debugging

   To avoid large logs, revert error_log level back and reload nginx again.

3. Final Answer:

   Set error_log /var/log/nginx/error.log debug;, reload nginx, then revert after debugging -> Option D

4. Quick Check:

   Temporary debug = enable then revert [OK]

Hint: Enable debug, reload, then revert to avoid big logs [OK]

Common Mistakes:

• Leaving debug mode enabled permanently
• Deleting logs instead of controlling debug level
• Disabling logging disables debug info