# grpcserver

The `grpcserver` package provides the implementation of the gRPC server for handling remote procedure calls in Grafana. It enables communication between clients and the Grafana server using the gRPC protocol.

## Structure

- `service.go`: This file contains the main configuration of the gRPC service, which implements the `registry.BackgroundService` interface.
- `interceptors`: This folder contains the middleware functions used for intercepting and modifying gRPC requests and responses.
- `context`: This folder contains helpers related to getting and setting values in `context.Context`.
- `health.go`: This provides the implementation of the gRPC health check service, which is automatically registered with the gRPC server.
- `reflection.go`: This provides the implementation of the gRPC reflection service, which is automatically registered with the gRPC server.

## Usage

Enable the gRPC server in Grafana by setting the `grpcServer` feature toggle to `true` in your `custom.ini` configuration file.

```ini
[feature_toggles]
grpcServer = true
```

You can specify the gRPC server specific settings in the `grpc_server` section of the configuration file.

```ini
[grpc_server]
network = "tcp"
address = "127.0.0.1:10000"
use_tls = false
cert_file =
key_file =
# this will log the request and response for each unary gRPC call
enable_logging = false
# Maximum size of a message that can be received in bytes. If not set, uses the gRPC default (4MiB).
max_recv_msg_size =
# Maximum size of a message that can be sent in bytes. If not set, uses the gRPC default (unlimited).
max_send_msg_size =
```

### Optional: Connection Management and Load Balancing

These settings help with:

- **Resource management**: Prevent resource leaks from idle connections
- **Connection health**: Detect and clean up dead connections
- **Load balancing**: Force connection recycling for better distribution across multiple server instances
- **DoS protection**: Rate limit keepalive pings from clients

```ini
# Connection management options
# Maximum amount of time a connection may exist before it will be closed
max_connection_age = 300s
# Additional time to allow for pending RPCs to complete before forcibly closing connections
max_connection_age_grace = 10s
# Maximum amount of idle time before a connection is closed
max_connection_idle = 300s
# Frequency of server-to-client pings to check if a connection is still active
keepalive_time = 30s
# Amount of time the server waits for a response to keepalive pings before closing the connection
keepalive_timeout = 5s
# Minimum amount of time a client should wait before sending a keepalive ping
keepalive_min_time = 5s
```

## Example Services

View [health.go] and [reflection.go] for examples of how to implement gRPC services in Grafana. These services are currently initialized by the [background service registry](../../registry/backgroundsvcs/background_services.go).