Log rotation in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the log file path in the nginx configuration.

Nginx

access_log [1];

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

A/var/log/nginx/access.log

B/etc/nginx/nginx.conf

C/tmp/nginx.log

D/usr/share/nginx/html

Attempts:

3 left

💡 Hint

Common Mistakes

Using the configuration file path instead of the log file path.

Using a directory path instead of a file path.

The access_log directive requires the full path to the log file, commonly /var/log/nginx/access.log.

2fill in blank

medium

Complete the command to reload nginx after log rotation.

Nginx

sudo systemctl [1] nginx

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Areload

Bstop

Crestart

Dstatus

Attempts:

3 left

💡 Hint

Common Mistakes

Using stop or restart causes downtime.

Using status does not reload configuration.

The reload command tells nginx to reload its configuration and reopen log files without stopping the service.

3fill in blank

hard

Fix the error in the logrotate configuration snippet for nginx logs.

Nginx

/var/log/nginx/*.log {
    daily
    missingok
    rotate [1]
    compress
    delaycompress
    notifempty
    create 0640 www-data adm
    sharedscripts
    postrotate
        /bin/systemctl reload nginx > /dev/null 2>&1 || true
    endscript
}

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

A5

Breload

Crestart

D7

Attempts:

3 left

💡 Hint

Common Mistakes

Using commands like reload or restart instead of a number.

Omitting the rotate count.

The rotate directive expects a number indicating how many rotated logs to keep, e.g., 7.

4fill in blank

hard

Fill both blanks to complete the logrotate postrotate script for nginx.

Nginx

/var/log/nginx/*.log {
    postrotate
        [1] nginx [2] > /dev/null 2>&1 || true
    endscript
}

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

Ainvoke-rc.d

Breload

Crestart

Dservice

Attempts:

3 left

💡 Hint

Common Mistakes

Using restart causes downtime.

Using service instead of invoke-rc.d in some systems.

The invoke-rc.d command is used to call service scripts, and reload tells nginx to reload logs without downtime.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps log file names to their sizes if size is greater than 0.

Nginx

log_sizes = [1]: [2] for [1] in [3] if os.path.getsize([1]) > 0

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

Alog

Bos.path.getsize(log)

Clogs

Dfile

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

Not filtering files with size > 0.

This comprehension creates a dictionary where keys are log file names and values are their sizes, filtering only files larger than zero bytes.

Practice

1. What is the main purpose of log rotation in nginx?

easy

A. To delete all logs automatically every hour

B. To stop nginx from creating logs

C. To keep log files from growing too large and manage disk space

D. To combine all logs into one big file

Solution

1. Step 1: Understand log file growth

   Log files grow continuously as nginx runs, which can fill up disk space.

2. Step 2: Purpose of log rotation

   Log rotation splits logs into smaller files and removes or archives old ones to save space.

3. Final Answer:

   To keep log files from growing too large and manage disk space -> Option C

4. Quick Check:

   Log rotation = Manage log size and disk space [OK]

Hint: Log rotation prevents huge log files filling your disk [OK]

Common Mistakes:

• Thinking logs are deleted every hour automatically
• Believing log rotation stops logging
• Assuming logs are merged into one file

2. Which of the following is the correct directive to reload nginx after log rotation?

easy

A. systemctl restart nginx

B. nginx -s reload

C. service nginx stop

D. nginx --rotate-logs

Solution

1. Step 1: Identify nginx reload command

   The command nginx -s reload tells nginx to reload configuration and reopen log files without stopping the service.

2. Step 2: Compare other options

   systemctl restart nginx restarts nginx fully, which is heavier. service nginx stop stops nginx, and nginx --rotate-logs is not a valid command.

3. Final Answer:

   nginx -s reload -> Option B

4. Quick Check:

   Reload nginx logs = nginx -s reload [OK]

Hint: Use 'nginx -s reload' to reopen logs after rotation [OK]

Common Mistakes:

• Using full restart instead of reload
• Stopping nginx instead of reloading
• Using invalid nginx commands

3. Given this logrotate config snippet for nginx logs:

/var/log/nginx/*.log {
  daily
  missingok
  rotate 7
  compress
  delaycompress
  notifempty
  create 0640 www-data adm
  sharedscripts
  postrotate
    nginx -s reload
  endscript
}

What happens when logrotate runs?

medium

A. Logs rotate daily, delete all old logs, and nginx stops

B. Logs rotate weekly, keep 7 uncompressed files, and nginx restarts

C. Logs never rotate because of syntax error

D. Logs rotate daily, keep 7 old compressed files, and nginx reloads after rotation

Solution

1. Step 1: Analyze rotation frequency and retention

   The daily directive means logs rotate every day. rotate 7 keeps 7 old log files.

2. Step 2: Check compression and reload

   compress compresses old logs, delaycompress delays compression by one cycle. postrotate runs nginx -s reload to reopen logs.

3. Final Answer:

   Logs rotate daily, keep 7 old compressed files, and nginx reloads after rotation -> Option D

4. Quick Check:

   Daily rotate + 7 files + reload nginx = C [OK]

Hint: Look for 'daily', 'rotate 7', and 'postrotate nginx -s reload' [OK]

Common Mistakes:

• Confusing daily with weekly rotation
• Ignoring compression directives
• Assuming nginx restarts instead of reloads

4. You configured logrotate for nginx but notice logs are not rotating. Which is the most likely cause?

medium

A. The log file path in logrotate config is incorrect

B. The compress directive is missing

C. The rotate number is set to 0

D. The postrotate script does not reload nginx

Solution

1. Step 1: Check log file path correctness

   If the log file path in the logrotate config does not match actual nginx log locations, rotation won't happen.

2. Step 2: Evaluate other options

   Not reloading nginx delays log reopening but rotation still occurs. rotate 0 disables rotation but is rare. Missing compress only affects compression, not rotation.

3. Final Answer:

   The log file path in logrotate config is incorrect -> Option A

4. Quick Check:

   Wrong log path = no rotation [OK]

Hint: Verify log file paths in config match actual nginx logs [OK]

Common Mistakes:

• Assuming missing reload stops rotation
• Thinking compression affects rotation
• Ignoring log file path accuracy

5. You want to rotate nginx logs only when they reach 100MB size, keep 5 backups, compress old logs, and reload nginx smoothly. Which logrotate config snippet achieves this?

hard

A. /var/log/nginx/*.log {
size 100M
rotate 5
compress
missingok
notifempty
sharedscripts
postrotate
nginx -s reload
endscript
}

B. /var/log/nginx/*.log {
daily
rotate 5
compress
postrotate
systemctl restart nginx
endscript
}

C. /var/log/nginx/*.log {
size 100M
rotate 10
delaycompress
postrotate
nginx -s reload
endscript
}

D. /var/log/nginx/*.log {
weekly
rotate 5
compress
postrotate
nginx -s reload
endscript
}

Solution

1. Step 1: Match size and rotate count requirements

   /var/log/nginx/*.log { size 100M rotate 5 compress missingok notifempty sharedscripts postrotate nginx -s reload endscript } uses size 100M to rotate at 100MB and rotate 5 to keep 5 backups, matching requirements.

2. Step 2: Check compression and reload commands

   /var/log/nginx/*.log { size 100M rotate 5 compress missingok notifempty sharedscripts postrotate nginx -s reload endscript } includes compress and postrotate nginx -s reload for smooth reload. Others use wrong rotate count, timing, or restart instead of reload.

3. Final Answer:

   /var/log/nginx/*.log { size 100M rotate 5 compress missingok notifempty sharedscripts postrotate nginx -s reload endscript } -> Option A

4. Quick Check:

   Size 100M + rotate 5 + compress + reload nginx = A [OK]

Hint: Look for 'size 100M', 'rotate 5', 'compress', and 'nginx -s reload' [OK]

Common Mistakes:

• Using daily or weekly instead of size-based rotation
• Restarting nginx instead of reloading
• Wrong rotate count or missing compress