Understanding Nginx Proxy Pass Path Matching and Configuration Details

This article explains the importance of the trailing slash in an nginx proxy_pass directive when using a ^~ location match, showing how it changes the way the matched path is forwarded.

Example with a trailing slash:

location ^~ /hahashen/ {
    proxy_cache js_cache;
    proxy_set_header Host js.test.com;
    proxy_pass http://js.test.com/;
}

# Request http://servername/hahashen/test.html is proxied to http://js.test.com/test.html

Example without a trailing slash:

location ^~ /hahashen/ {
    proxy_cache js_cache;
    proxy_set_header Host js.test.com;
    proxy_pass http://js.test.com;
}

# Request http://servername/hahashen/test.html is proxied to http://js.test.com/hahashen/test.html

Using rewrite to achieve the desired slash behavior:

location ^~ /hahashen/ {
    proxy_cache js_cache;
    proxy_set_header Host js.test.com;
    rewrite /hahashen/(.+)$ /$1 break;
    proxy_pass http://js.test.com;
}

Additional configuration details include defining an upstream group and a server block with extensive proxy settings:

upstream app {
    server 192.168.20.40:9081 max_fails=3 fail_timeout=15s;
    server 192.168.20.39:9081 max_fails=3 fail_timeout=15s;
}

server {
    listen 80;
    server_name image.hahashen.com;
    access_log /data/nginx/logs/hahashen-access.log main;
    error_log /data/nginx/logs/hahashen-error.log;
    location / {
        proxy_pass http://app;
        proxy_redirect off;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header REMOTE-HOST $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_connect_timeout 300;
        proxy_send_timeout 300;
        proxy_read_timeout 600;
        proxy_buffer_size 256k;
        proxy_buffers 4 256k;
        proxy_busy_buffers_size 256k;
        proxy_temp_file_write_size 256k;
        proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504 http_404;
        proxy_max_temp_file_size 128m;
    }
    location /api/ {
        proxy_pass http://blog.hahashen.com;
    }
    location /sub/ {
        proxy_pass http://dt.hahashen.com/;
    }
}

Explanation of request routing:

Requests to http://image.hahashen.com are load‑balanced between 192.168.20.40:9081 and 192.168.20.39:9081 .

Requests to http://image.hahashen.com/api/ are proxied to http://blog.hahashen.com/api/ .

Requests to http://image.hahashen.com/sub/ are proxied to http://dt.hahashen.com/ .