Map directive for variable mapping in Nginx - Mini Project: Build & Apply

Map Directive for Variable Mapping in Nginx

📖 Scenario: You are configuring an Nginx web server to serve different content based on the client's IP address range. You want to use the map directive to create a variable that changes its value depending on the client's IP.

🎯 Goal: Build an Nginx configuration that uses the map directive to set a variable called $client_type to internal for IPs in the 192.168.1.0/24 range and external for all other IPs.

📋 What You'll Learn

Create a map block named client_type that maps $remote_addr to internal or external

Define the IP range 192.168.1.0/24 as internal

Set the default value to external

Use the $client_type variable inside the server block

Print the value of $client_type in the response header

💡 Why This Matters

🌍 Real World

In real web servers, the <code>map</code> directive helps customize responses based on client IPs, user agents, or other variables without changing the main server logic.

💼 Career

Knowing how to use <code>map</code> in Nginx is valuable for DevOps engineers and system administrators to implement flexible, efficient server configurations.

1

Create the basic Nginx server block

Write an Nginx configuration with a server block listening on port 8080 and a location / that returns a simple text response.

Nginx

server {
    listen 8080;
    location / {
        return 200 'Hello from Nginx';
    }
}

# Your code here

Need a hint?

Start with a simple server block that listens on port 8080 and returns a text response.

2

Add a map directive to define $client_type

Add a map directive outside the server block that maps $remote_addr to internal for IP range 192.168.1.0/24 and sets the default to external. The variable name must be client_type.

Nginx

map $remote_addr $client_type {
    # Define IP range mapping here
}

server {
    listen 8080;
    location / {
        return 200 'Hello from Nginx';
    }
}

# Your code here

Need a hint?

The map directive must be placed outside the server block. Use the IP range 192.168.1.0/24 as the key and internal as the value.

3

Use the $client_type variable in the server block

Modify the location / block inside the server block to add a response header named X-Client-Type with the value of the $client_type variable.

Nginx

map $remote_addr $client_type {
    192.168.1.0/24 internal;
    default external;
}

server {
    listen 8080;
    location / {
        add_header X-Client-Type $client_type;
        return 200 'Hello from Nginx';
    }
}

# Your code here

Need a hint?

Use the add_header directive inside the location / block to add the header.

4

Test the configuration output

Run the Nginx server with this configuration and simulate a request from IP 192.168.1.5. Print the response header X-Client-Type to confirm it shows internal.

Nginx

# Simulate a request from 192.168.1.5 and print the X-Client-Type header
# Your code here

Need a hint?

Since this is a configuration file, simulate the output by printing the expected header line.