Migrating and Upgrading Nginx

nginx -t
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful

# Send signal to upgrade Nginx without downtime
kill -USR1 $(cat /var/run/nginx.pid)

# On source server<br>scp /etc/nginx/nginx.conf user@target-server:/etc/nginx/<br><br>scp -r /etc/nginx/conf.d/ user@target-server:/etc/nginx/

<VirtualHost *:80>
    ServerName example.com
    DocumentRoot /var/www/html
    DirectoryIndex index.html
    Alias /images /var/www/images

    <Directory "/var/www/html">
        Options Indexes
        AllowOverride None
    </Directory>

    ErrorLog /var/log/apache2/error.log
    CustomLog /var/log/apache2/access.log combined
</VirtualHost>

server {
    listen 80;
    server_name example.com;
    root /var/www/html;
    index index.html;

    location /images {
        alias /var/www/images;
    }

    location / {
        autoindex on;
    }

    error_log /var/log/nginx/error.log;
    access_log /var/log/nginx/access.log;
}

# Old configuration (deprecated)
limit_zone my_zone:10m rate=1r/s;

server {
    limit_req zone=my_zone burst=5 nodelay;
}

# New configuration (recommended)
limit_req_zone $binary_remote_addr zone=my_zone:10m rate=1r/s;

server {
    limit_req zone=my_zone burst=5 nodelay;
}

sudo cp /etc/nginx/nginx.conf.backup /etc/nginx/nginx.conf
sudo systemctl restart nginx

./configure --with-compat --add-dynamic-module=/path/to/module
make
make install

# Test new config syntax
nginx -t -c /etc/nginx/nginx.conf

# Dry-run with new config
nginx -t -c /etc/nginx/nginx-new.conf

# List loaded modules
nginx -V 2>&1 | grep --with-colon --only-matching 'modules:.*'

# Compare versions
nginx -v
nginx -V 2>&1 | grep --only-matching 'nginx version:.*'

# Log configuration changes in a centralized file
echo "[2026-04-05 10:00:00] Updated server block to use TLS 1.3" >> /var/log/nginx/config_changes.log

# Upstream configuration for blue and green environments
upstream backend_blue {
    server 10.0.1.10:8080;
    server 10.0.1.11:8080;
}

upstream backend_green {
    server 10.0.2.10:8080;
    server 10.0.2.11:8080;
}

# Main server block
server {
    listen 80;
    server_name example.com;

    # Route to blue environment by default
    location / {
        proxy_pass http://backend_blue;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }

    # Health check endpoint
    location /health {
        access_log off;
        return 200 "healthy\n";
        add_header Content-Type text/plain;
    }
}