Solving gRPC Inbound Connectivity Issues in AKS using NGINX (grpc_pass)

External clients were unable to connect to a gRPC service exposed via a public Load Balancer.

Unlike Basic Load Balancers, Standard LBs are secure by default: All inbound traffic is blocked. Traffic is only allowed if explicitly permitted via an NSG, so Overview solution diagram —

Client
   ↓
Azure Standard Load Balancer (Public IP)
   ↓
VM (NGINX with TLS + HTTP/2)
   ↓
Internal gRPC service (AKS)

NGINX supports gRPC via the grpc_pass directive, which makes it ideal for routing requests to internal services.

NGINX Configuration

server {

listen 443 ssl http2;
server_name my-grpc-domain.com;

ssl_certificate cert/server-cert.pem;
    ssl_certificate_key cert/server-key.pem;

    location / {
        grpc_pass grpcs://internal-grpc-service:443;

        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

        proxy_connect_timeout 180;
        proxy_send_timeout 180;
        proxy_read_timeout 180;
    }

    location /ping {
        return 200 'pong!';
    }
}