API versioning with routing in Nginx - Mini Project: Build & Apply

API Versioning with Routing in Nginx

📖 Scenario: You are managing a web server that hosts an API. The API has two versions: v1 and v2. You want to route incoming requests to the correct API version based on the URL path.For example, requests to /api/v1/ should go to the v1 backend, and requests to /api/v2/ should go to the v2 backend.

🎯 Goal: Configure Nginx to route API requests to the correct backend based on the API version in the URL path.

📋 What You'll Learn

Create an Nginx server block listening on port 80

Route requests starting with /api/v1/ to the backend at http://localhost:5001

Route requests starting with /api/v2/ to the backend at http://localhost:5002

Return a 404 error for any other API paths

💡 Why This Matters

🌍 Real World

Many companies maintain multiple versions of their APIs to support old and new clients. Routing requests correctly ensures smooth operation and backward compatibility.

💼 Career

Understanding how to configure Nginx for API versioning is a common task for DevOps engineers and backend developers managing web services.

1

Create the basic Nginx server block

Create an Nginx server block that listens on port 80 and has a root location / that returns a simple text response "Welcome to API server".

Nginx

# Create a server block listening on port 80
# Add a location / that returns "Welcome to API server"

Hint

Use listen 80; inside the server block. Use location / { return 200 'Welcome to API server'; } to respond with text.

2

Add routing for API version 1

Inside the existing server block, add a location block for /api/v1/ that proxies requests to http://localhost:5001.

Nginx

server {
    listen 80;

    location / {
        return 200 'Welcome to API server';
    }

    # Add location /api/v1/ to proxy to http://localhost:5001

Hint

Use location /api/v1/ { proxy_pass http://localhost:5001; } inside the server block.

3

Add routing for API version 2

Inside the existing server block, add a location block for /api/v2/ that proxies requests to http://localhost:5002.

Nginx

server {
    listen 80;

    location / {
        return 200 'Welcome to API server';
    }

    location /api/v1/ {
        proxy_pass http://localhost:5001;
    }

    # Add location /api/v2/ to proxy to http://localhost:5002

Hint

Use location /api/v2/ { proxy_pass http://localhost:5002; } inside the server block.

4

Return 404 for other API paths

Inside the existing server block, add a location block for /api/ that returns a 404 error for any paths not matched by previous locations.

Nginx

server {
    listen 80;

    location / {
        return 200 'Welcome to API server';
    }

    location /api/v1/ {
        proxy_pass http://localhost:5001;
    }

    location /api/v2/ {
        proxy_pass http://localhost:5002;
    }

    # Add location /api/ to return 404 for other API paths

Hint

Use location /api/ { return 404; } to catch other API paths.

Practice

1. What is the main purpose of using API versioning with routing in nginx?

easy

A. To block all API requests except the latest version

B. To combine all API versions into a single endpoint

C. To run multiple API versions side by side and route requests accordingly

D. To disable routing and serve static files only

Solution

1. Step 1: Understand API versioning concept

   API versioning allows different versions of an API to coexist, so clients using older versions still work.

2. Step 2: Role of nginx routing

   nginx uses location blocks to route requests to the correct API version based on the URL path.

3. Final Answer:

   To run multiple API versions side by side and route requests accordingly -> Option C

4. Quick Check:

   API versioning = multiple versions side by side [OK]

Hint: API versioning means routing requests to different versions [OK]

Common Mistakes:

• Thinking API versioning disables old versions
• Assuming all versions merge into one endpoint
• Confusing routing with blocking requests

2. Which nginx configuration snippet correctly routes requests to API version v1 at path /api/v1/?

easy

A. location /api/v1/ { proxy_pass http://backend_v1; }

B. location /api/v1 { proxy_pass http://backend_v1; }

C. location /api/v1/* { proxy_pass http://backend_v1; }

D. location /api/v1$ { proxy_pass http://backend_v1; }

Solution

1. Step 1: Understand nginx location matching

   Using location /api/v1/ matches all requests starting with /api/v1/, including subpaths.

2. Step 2: Check syntax correctness

   location /api/v1/ { proxy_pass http://backend_v1; } uses correct syntax without wildcards or regex, which nginx does not support in this form.

3. Final Answer:

   location /api/v1/ { proxy_pass http://backend_v1; } -> Option A

4. Quick Check:

   Trailing slash in location matches subpaths [OK]

Hint: Use trailing slash in location to match all subpaths [OK]

Common Mistakes:

• Using wildcards (*) in location which nginx does not support
• Missing trailing slash causing partial matches
• Using regex syntax without ~

3. Given this nginx config snippet, what backend will handle a request to /api/v2/users?

location /api/v1/ {
  proxy_pass http://backend_v1;
}
location /api/v2/ {
  proxy_pass http://backend_v2;
}

medium

A. http://backend_v2

B. No backend, 404 error

C. http://backend_v1

D. Both backends in round-robin

Solution

1. Step 1: Match request path to location blocks

   The request path /api/v2/users starts with /api/v2/, so it matches the second location block.

2. Step 2: Determine proxy backend

   The matching location proxies to http://backend_v2, so this backend handles the request.

3. Final Answer:

   http://backend_v2 -> Option A

4. Quick Check:

   Request path prefix matches location prefix [OK]

Hint: Match URL prefix to location prefix to find backend [OK]

Common Mistakes:

• Choosing backend_v1 for /api/v2/ path
• Assuming nginx load balances both backends automatically
• Thinking unmatched paths cause proxy to backend_v1

4. Identify the error in this nginx config for API versioning:

location /api/v1 {
  proxy_pass http://backend_v1;
}
location /api/v2/ {
  proxy_pass http://backend_v2;
}

medium

A. proxy_pass must use IP address, not hostname

B. proxy_pass URLs must include trailing slash

C. location blocks cannot be adjacent

D. Missing trailing slash in first location causes incorrect routing

Solution

1. Step 1: Check location path consistency

   The first location uses /api/v1 without trailing slash, which matches only exact path or prefix differently than /api/v1/.

2. Step 2: Understand routing impact

   Requests like /api/v1/users won't match the first location correctly, causing routing errors.

3. Final Answer:

   Missing trailing slash in first location causes incorrect routing -> Option D

4. Quick Check:

   Trailing slash in location matters for prefix matching [OK]

Hint: Always use trailing slash in location for API version prefixes [OK]

Common Mistakes:

• Ignoring trailing slash difference in location paths
• Thinking proxy_pass URL must have trailing slash
• Believing location blocks cannot be next to each other

5. You want to support API versions v1 and v2 in nginx, but also redirect any request to /api/ without version to v2 by default. Which config snippet achieves this correctly?

hard

A. location /api/ { proxy_pass http://backend_v2; }
location /api/v1/ { proxy_pass http://backend_v1; }

B. location /api/v1/ { proxy_pass http://backend_v1; }
location /api/v2/ { proxy_pass http://backend_v2; }
location /api/ { return 301 /api/v2/; }

C. location /api/ { proxy_pass http://backend_v1; }
location /api/v2/ { proxy_pass http://backend_v2; }

D. location /api/v1/ { proxy_pass http://backend_v1; }
location /api/v2/ { proxy_pass http://backend_v2; }
location /api/ { proxy_pass http://backend_v2; }

Solution

1. Step 1: Define explicit version locations

   Locations for /api/v1/ and /api/v2/ proxy requests to respective backends.

2. Step 2: Redirect base /api/ to default version

   Using return 301 /api/v2/; in /api/ location sends clients to v2 URL, ensuring default version usage.

3. Final Answer:

   location /api/v1/ { proxy_pass http://backend_v1; } location /api/v2/ { proxy_pass http://backend_v2; } location /api/ { return 301 /api/v2/; } -> Option B

4. Quick Check:

   Redirect base path to default version with return 301 [OK]

Hint: Use return 301 to redirect base API path to default version [OK]

Common Mistakes:

• Proxying /api/ directly instead of redirecting
• Overlapping location blocks causing conflicts
• Using proxy_pass in /api/ without redirect