Keepalive connections in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enable keepalive connections in the upstream block.

Nginx

upstream backend {
    server backend1.example.com;
    [1] 32;
}

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

Alisten

Bkeepalive

Cproxy_pass

Dserver

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'proxy_pass' inside the upstream block instead of 'keepalive'.

Confusing 'listen' directive with keepalive settings.

The keepalive directive inside the upstream block sets the number of idle keepalive connections to upstream servers.

2fill in blank

medium

Complete the code to enable keepalive connections in the proxy settings.

Nginx

location / {
    proxy_pass http://backend;
    proxy_http_version 1.1;
    [1] 100;
}

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

Aproxy_keepalive

Bkeepalive_timeout

Cproxy_set_header

Dkeepalive_requests

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'proxy_keepalive' which is not a valid directive.

Confusing 'keepalive_timeout' with enabling keepalive requests.

The keepalive_requests directive enables keepalive connections by specifying how many requests can be sent over a single keepalive connection.

3fill in blank

hard

Fix the error in the keepalive timeout configuration.

Nginx

keepalive_timeout [1] 20s;

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

Aoff

Bon

Ckeepalive

Dproxy

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'on' which is invalid for keepalive_timeout.

Using 'keepalive' or 'proxy' which are not valid values here.

The keepalive_timeout directive accepts a time value or 'off' to disable it. Using 'off' disables keepalive timeout.

4fill in blank

hard

Fill both blanks to configure upstream keepalive connections and proxy settings correctly.

Nginx

upstream backend {
    server backend1.example.com;
    [1] 64;
}

location / {
    proxy_pass http://backend;
    proxy_http_version 1.1;
    [2] 100;
}

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

Akeepalive

Bkeepalive_requests

Cproxy_set_header

Dkeepalive_timeout

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing 'keepalive_timeout' with 'keepalive_requests'.

Using 'proxy_set_header' instead of keepalive directives.

The keepalive directive in the upstream block sets the number of idle keepalive connections. The keepalive_requests directive sets how many requests can be sent over one keepalive connection.

5fill in blank

hard

Fill all three blanks to configure keepalive connections with timeout and request limits.

Nginx

upstream backend {
    server backend1.example.com;
    [1] 32;
}

location / {
    proxy_pass http://backend;
    proxy_http_version 1.1;
    [2] 100;
    [3] 75s;
}

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

Akeepalive

Bkeepalive_requests

Ckeepalive_timeout

Dproxy_set_header

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'proxy_set_header' instead of keepalive directives.

Confusing 'keepalive_timeout' with 'keepalive_requests'.

The keepalive directive sets idle connections in upstream. keepalive_requests limits requests per keepalive connection. keepalive_timeout sets the timeout for keepalive connections.

Practice

1. What is the main benefit of using keepalive connections in nginx?

easy

A. They disable caching on the server.

B. They close connections immediately after each request.

C. They increase the number of open connections indefinitely.

D. They reuse the same connection for multiple requests, improving speed.

Solution

1. Step 1: Understand what keepalive connections do

   Keepalive connections allow the same connection to be reused for multiple requests instead of opening a new one each time.

2. Step 2: Identify the benefit of reusing connections

   Reusing connections reduces the time and resources needed to establish new connections, thus improving speed and reducing server load.

3. Final Answer:

   They reuse the same connection for multiple requests, improving speed. -> Option D

4. Quick Check:

   Keepalive = reuse connection for speed [OK]

Hint: Keepalive means reuse connection to speed up requests [OK]

Common Mistakes:

• Thinking keepalive closes connections immediately
• Believing keepalive increases open connections endlessly
• Confusing keepalive with caching

2. Which of the following is the correct syntax to set the keepalive timeout to 30 seconds in nginx?

easy

A. keepalive_timeout 30s

B. keepalive_timeout 30;

C. keepalive_timeout: 30s;

D. keepalive_timeout = 30;

Solution

1. Step 1: Recall nginx directive syntax

   Nginx directives use the format: directive_name value; without equal signs or colons.

2. Step 2: Check the correct value format for time

   Timeout values in nginx can be specified as numbers (seconds) without units or with units like 's'. Both are accepted, but the common practice is just a number for seconds.

3. Final Answer:

   keepalive_timeout 30; -> Option B

4. Quick Check:

   Directive syntax = name value; no '=' or ':' [OK]

Hint: Nginx directives use 'name value;' syntax without '=' [OK]

Common Mistakes:

• Using '=' sign in directive
• Adding colon ':' after directive name
• Adding units like 's' unnecessarily

3. Given this nginx configuration snippet:

keepalive_timeout 10;
keepalive_requests 100;

What happens after 100 requests on the same keepalive connection?

medium

A. The connection is closed and a new one is opened for the next request.

B. The connection stays open indefinitely.

C. The server resets the timeout to 10 seconds again.

D. The connection is closed immediately after the first request.

Solution

1. Step 1: Understand keepalive_requests directive

   This directive limits how many requests can be sent over one keepalive connection before it closes.

2. Step 2: Apply the limit of 100 requests

   After 100 requests, nginx closes the connection and opens a new one for the next request to avoid stale connections.

3. Final Answer:

   The connection is closed and a new one is opened for the next request. -> Option A

4. Quick Check:

   keepalive_requests = max requests per connection [OK]

Hint: keepalive_requests limits requests per connection [OK]

Common Mistakes:

• Thinking connection stays open forever
• Confusing timeout with request count
• Assuming connection closes after first request

4. You set keepalive_timeout 20; but clients report connections close too quickly. Which is the likely mistake?

medium

A. The keepalive_requests is set to 1, closing after one request.

B. The timeout value is too low for client needs.

C. You forgot to reload nginx after changing config.

D. The server is running an old nginx version without keepalive support.

Solution

1. Step 1: Check common reasons for config changes not applying

   If nginx is not reloaded or restarted after config changes, old settings remain active.

2. Step 2: Confirm reload necessity

   After changing keepalive_timeout, nginx must be reloaded with nginx -s reload or restarted to apply changes.

3. Final Answer:

   You forgot to reload nginx after changing config. -> Option C

4. Quick Check:

   Config changes need reload to apply [OK]

Hint: Reload nginx after config changes to apply them [OK]

Common Mistakes:

• Assuming timeout value alone fixes issue
• Ignoring need to reload nginx
• Blaming nginx version without checking

5. You want to optimize nginx for many short requests by keeping connections alive but closing them after 15 seconds or 50 requests, whichever comes first. Which configuration is correct?

hard

A. keepalive_timeout 15;\nkeepalive_requests 50;

B. keepalive_timeout 50;\nkeepalive_requests 15;

C. keepalive_timeout 15s;\nkeepalive_requests 50s;

D. keepalive_timeout 15s;\nkeepalive_requests 50; keepalive_disable none;

Solution

1. Step 1: Set keepalive_timeout to 15 seconds

   This controls how long a connection stays open waiting for new requests.

2. Step 2: Set keepalive_requests to 50

   This limits the number of requests per connection before closing it.

3. Step 3: Verify correct syntax and values

   keepalive_timeout 15;\nkeepalive_requests 50; uses correct syntax and values matching the requirement: 15 seconds timeout and 50 requests limit.

4. Final Answer:

   keepalive_timeout 15;\nkeepalive_requests 50; -> Option A

5. Quick Check:

   Timeout 15 + Requests 50 = correct config [OK]

Hint: Timeout sets seconds, requests sets max requests per connection [OK]

Common Mistakes:

• Swapping timeout and requests values
• Adding units to keepalive_requests
• Using invalid directives like keepalive_disable