Subgraph load balancer nginx

Load balancer VPS

resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 10s;

# Manual random load balance
map $request_id $backend_host {
    default DOMAIN_1;
    ~*[13579a-f]$ DOMAIN_2;  # if last char odd → subgraph2
}

server {
    listen 127.0.0.1:80;
    server_name loadbalancer.domain.com;

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

    location /health {
        return 200 "Load balancer operational\n";
    }

    location / {
        proxy_pass https://$backend_host;
        proxy_http_version 1.1;
        proxy_ssl_server_name on;
        proxy_set_header Host $backend_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }

    location /subgraphs/ {
        proxy_pass https://$backend_host;
        proxy_http_version 1.1;
        proxy_ssl_server_name on;
        proxy_set_header Host $backend_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }

    location /node {
        proxy_pass https://$backend_host/node;
        proxy_http_version 1.1;
        proxy_ssl_server_name on;
        proxy_set_header Host $backend_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }

    location /index-node/graphql {
        proxy_pass https://$backend_host/index-node/graphql;
        proxy_http_version 1.1;
        proxy_ssl_server_name on;
        proxy_set_header Host $backend_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }

    location /subscriptions {
        proxy_pass https://$backend_host/subscriptions;
        proxy_http_version 1.1;
        proxy_ssl_server_name on;
        proxy_set_header Host $backend_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }

    location /ipfs/ {
        proxy_pass https://$backend_host/ipfs/;
        proxy_http_version 1.1;
        proxy_ssl_server_name on;
        proxy_set_header Host $backend_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;

        proxy_request_buffering off;
        proxy_buffering off;

        proxy_connect_timeout 600;
        proxy_send_timeout 600;
        proxy_read_timeout 600;
        send_timeout 600;

        client_max_body_size 500M;
    }
}

test-script.sh

#!/bin/bash
subgraph1=0
subgraph2=0

for i in {1..10}; do
    echo "Request $i:"
    # Save full headers to a file for inspection
    curl -sLI "https://loadbalancer.domain.com/subgraphs/name/exchange" > headers.txt

    # Print all headers for debugging
    echo "Full headers for request $i:"
    cat headers.txt
    echo "------------------------------"

    # Try multiple header names
    for header in "X-Backend-Server" "X-Used-Backend" "X-Proxy-Host"; do
        backend=$(grep -i "$header" headers.txt | awk -F': ' '{print $2}' | tr -d '\r')
        if [ -n "$backend" ]; then
            echo "Found $header: $backend"

            if [[ "$backend" == *"subgraph1"* ]]; then
                ((subgraph1++))
                backend_found=1
                break
            elif [[ "$backend" == *"subgraph2"* ]]; then
                ((subgraph2++))
                backend_found=1
                break
            fi
        fi
    done

    if [ -z "$backend_found" ]; then
        echo "No backend information found in request $i"
    fi

    echo ""
    sleep 1  # Small delay between requests
done

echo "=== Distribution Results ==="
echo "subgraph1: $subgraph1 requests"
echo "subgraph2: $subgraph2 requests"

VPS 1

server {
    root /var/www/html;
    
    # Add index.php to the list if you are using PHP
    index index.html index.htm index.nginx-debian.html;
    
    server_name DOMAIN_1;

    location /node {
        proxy_pass http://127.0.0.1:8020;
    }

    location /subgraphs {
        proxy_pass http://127.0.0.1:8000/subgraphs;
    }

    location /index-node/graphql {
        proxy_pass http://127.0.0.1:8030/graphql;
    }

    location /subscriptions {
        proxy_pass http://127.0.0.1:8001/subgraphs;
    }

    location /ipfs/ {
        proxy_pass http://127.0.0.1:5001/;
        proxy_http_version 1.1;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;

        # Disable buffering for large file uploads
        proxy_request_buffering off;
        proxy_buffering off;

        # Increase timeouts (in seconds)
        proxy_connect_timeout 600;
        proxy_send_timeout 600;
        proxy_read_timeout 600;
        send_timeout 600;

        # Allow very large file uploads (500MB)
        client_max_body_size 500M;
    }

    add_header X-Backend-Server "subgraph1" always;  # Add this line

    listen 127.0.0.1:80;
}

VPS 2

server {
    root /var/www/html;
    
    # Add index.php to the list if you are using PHP
    index index.html index.htm index.nginx-debian.html;
    
    server_name DOMAIN_2;

    location /node {
        proxy_pass http://127.0.0.1:8020;
    }

    location /subgraphs {
        proxy_pass http://127.0.0.1:8000/subgraphs;
    }

    location /index-node/graphql {
        proxy_pass http://127.0.0.1:8030/graphql;
    }

    location /subscriptions {
        proxy_pass http://127.0.0.1:8001/subgraphs;
    }

    location /ipfs/ {
        proxy_pass http://127.0.0.1:5001/;
        proxy_http_version 1.1;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;

        # Disable buffering for large file uploads
        proxy_request_buffering off;
        proxy_buffering off;

        # Increase timeouts (in seconds)
        proxy_connect_timeout 600;
        proxy_send_timeout 600;
        proxy_read_timeout 600;
        send_timeout 600;

        # Allow very large file uploads (500MB)
        client_max_body_size 500M;
    }

    add_header X-Backend-Server "subgraph2" always;  # Add this line

    listen 127.0.0.1:80;
}