Canary deployments in Nginx - Mini Project: Build & Apply

Canary Deployments with Nginx

📖 Scenario: You are working as a DevOps engineer for a web service. Your team wants to test a new version of the website on a small percentage of users before fully releasing it. This is called a canary deployment. You will configure Nginx to route 10% of the traffic to the new version and 90% to the stable version.

🎯 Goal: Build an Nginx configuration that splits incoming user traffic so that 10% goes to the canary backend server and 90% goes to the stable backend server. This helps test new changes safely.

📋 What You'll Learn

Create an upstream block with two backend servers named stable_backend and canary_backend

Add a variable canary_weight set to 10 representing 10% traffic for canary

Use the split_clients directive to split traffic based on $remote_addr into canary and stable

Configure the server block to proxy requests to the correct backend based on the split

Print the final Nginx configuration that routes traffic accordingly

💡 Why This Matters

🌍 Real World

Canary deployments are used in real companies to reduce risk when releasing new software versions by testing changes on a small user group first.

💼 Career

DevOps engineers often configure load balancers like Nginx to manage traffic routing for canary deployments, improving software reliability and user experience.

1

Create upstream backend servers

Create an upstream block named backend with two servers: stable_backend at 192.168.1.10:80 and canary_backend at 192.168.1.20:80.

Nginx

# Your code here

Hint

Use the upstream directive to group backend servers.

2

Add canary traffic weight variable

Add a variable canary_weight and set it to 10 to represent 10% traffic for the canary deployment.

Nginx

upstream backend {
    server 192.168.1.10:80;  # stable_backend
    server 192.168.1.20:80;  # canary_backend
}

# Your code here

Hint

Use the map directive to create a variable based on $remote_addr.

3

Split traffic using split_clients

Use the split_clients directive with $remote_addr to split traffic into canary and stable groups. Assign canary to 10% and stable to 90%.

Nginx

upstream backend {
    server 192.168.1.10:80;  # stable_backend
    server 192.168.1.20:80;  # canary_backend
}

map $remote_addr $canary_weight {
    default 10;
}

# Your code here

Hint

The split_clients directive helps distribute traffic by percentage.

4

Configure server block to route traffic

Create a server block listening on port 80. Use an if statement to proxy requests to canary_backend if $deployment_group is canary, otherwise proxy to stable_backend. Use proxy_pass with http://backend and the correct server.

Nginx

upstream backend {
    server 192.168.1.10:80;  # stable_backend
    server 192.168.1.20:80;  # canary_backend
}

map $remote_addr $canary_weight {
    default 10;
}

split_clients "$remote_addr$canary_weight" $deployment_group {
    10% canary;
    * stable;
}

# Your code here

Hint

Use if inside location to route traffic based on $deployment_group.

Practice

1. What is the main purpose of a canary deployment in NGINX?

easy

A. To gradually route traffic between old and new application versions

B. To block all traffic during deployment

C. To increase server CPU usage intentionally

D. To disable logging temporarily

Solution

1. Step 1: Understand canary deployment concept

   Canary deployment means sending some traffic to a new version while most traffic still goes to the old version.

2. Step 2: Identify NGINX role in canary deployment

   NGINX controls traffic split using weights in upstream blocks to route requests gradually.

3. Final Answer:

   To gradually route traffic between old and new application versions -> Option A

4. Quick Check:

   Canary deployment = gradual traffic routing [OK]

Hint: Canary means gradual traffic shift, not blocking or disabling [OK]

Common Mistakes:

• Thinking canary blocks all traffic
• Confusing canary with load increase
• Assuming canary disables logging

2. Which NGINX configuration snippet correctly sets a 90% traffic weight to the old version and 10% to the new version?

easy

A. upstream backend { server old.example.com weight=90; server new.example.com weight=10; }

B. upstream backend { server old.example.com weight=10; server new.example.com weight=90; }

C. upstream backend { server old.example.com; server new.example.com; }

D. upstream backend { server old.example.com weight=100; server new.example.com weight=0; }

Solution

1. Step 1: Understand weight meaning in NGINX upstream

   Weight controls traffic share; higher weight means more traffic.

2. Step 2: Match weights to desired traffic split

   Old version should get 90%, new version 10%, so old weight=90, new weight=10.

3. Final Answer:

   upstream backend { server old.example.com weight=90; server new.example.com weight=10; } -> Option A

4. Quick Check:

   Weight 90 old, 10 new = 90% old traffic [OK]

Hint: Higher weight means more traffic; assign accordingly [OK]

Common Mistakes:

• Swapping weights between old and new servers
• Omitting weights defaults to equal traffic
• Setting weight=0 disables server completely

3. Given this NGINX upstream configuration:

upstream backend {
  server old.example.com weight=80;
  server new.example.com weight=20;
}

What percentage of traffic will be routed to new.example.com?

medium

A. 80%

B. 20%

C. 50%

D. 100%

Solution

1. Step 1: Calculate total weight

   Total weight = 80 (old) + 20 (new) = 100.

2. Step 2: Calculate new server traffic percentage

   New server traffic = (20 / 100) * 100% = 20%.

3. Final Answer:

   20% -> Option B

4. Quick Check:

   New server weight 20 of 100 total = 20% traffic [OK]

Hint: Traffic % = server weight / total weight * 100 [OK]

Common Mistakes:

• Confusing weight with percentage directly
• Adding weights incorrectly
• Assuming equal traffic without weights

4. You wrote this NGINX upstream block for canary deployment:

upstream backend {
  server old.example.com weight=70
  server new.example.com weight=30;
}

But NGINX fails to start. What is the error?

medium

A. Cannot use weight in upstream block

B. Weight values must be equal

C. Missing semicolon after first server directive

D. Server names must be IP addresses

Solution

1. Step 1: Check syntax of upstream block

   Each server directive must end with a semicolon in NGINX config.

2. Step 2: Identify missing semicolon

   First server line lacks semicolon after weight=70, causing syntax error.

3. Final Answer:

   Missing semicolon after first server directive -> Option C

4. Quick Check:

   Semicolons required after each directive [OK]

Hint: Check semicolons after each server line [OK]

Common Mistakes:

• Ignoring missing semicolon errors
• Thinking weights must be equal
• Assuming server names must be IPs

5. You want to deploy a new version with 5% traffic initially, then increase to 50% after testing. Which NGINX configuration approach supports this canary deployment best?

hard

A. Use limit_conn to limit new server connections

B. Use proxy_pass without weights to split traffic

C. Set weight=0 for new server until ready

D. Manually update weight values in upstream block and reload NGINX

Solution

1. Step 1: Understand canary traffic control in NGINX

   NGINX uses weights in upstream blocks to control traffic percentage per server.

2. Step 2: Adjust weights gradually and reload NGINX

   Manually changing weights from 5 to 50 and reloading NGINX safely shifts traffic as needed.

3. Final Answer:

   Manually update weight values in upstream block and reload NGINX -> Option D

4. Quick Check:

   Weight changes + reload = traffic control [OK]

Hint: Change weights and reload to shift traffic gradually [OK]

Common Mistakes:

• Using proxy_pass without weights for traffic split
• Setting weight=0 disables server, not gradual traffic
• Using limit_conn limits connections, not traffic percentage