grpc-node/packages/grpc-health-check/README.md

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# grpc-health-check
Health check client and service for use with gRPC-node.
## Background
This package exports both a client and server that adhere to the [gRPC Health Checking Protocol](https://github.com/grpc/grpc/blob/master/doc/health-checking.md).
By using this package, clients and servers can rely on common proto and service definitions. This means:
- Clients can use the generated stubs to health check _any_ server that adheres to the protocol.
- Servers do not reimplement common logic for publishing health statuses.
## Installation
Use the package manager [npm](https://www.npmjs.com/get-npm) to install `grpc-health-check`.
```bash
npm install grpc-health-check
```
## Usage
### Server
Any gRPC-node server can use `grpc-health-check` to adhere to the gRPC Health Checking Protocol.
The following shows how this package can be added to a pre-existing gRPC server.
```javascript 1.8
// Import package
let health = require('grpc-health-check');
// Define service status map. Key is the service name, value is the corresponding status.
// By convention, the empty string "" key represents that status of the entire server.
const statusMap = {
"ServiceFoo": proto.grpc.health.v1.HealthCheckResponse.ServingStatus.SERVING,
"ServiceBar": proto.grpc.health.v1.HealthCheckResponse.ServingStatus.NOT_SERVING,
"": proto.grpc.health.v1.HealthCheckResponse.ServingStatus.NOT_SERVING,
};
// Construct the service implementation
let healthImpl = new health.Implementation(statusMap);
// Add the service and implementation to your pre-existing gRPC-node server
server.addService(health.service, healthImpl);
```
Congrats! Your server now allows any client to run a health check against it.
### Client
Any gRPC-node client can use `grpc-health-check` to run health checks against other servers that follow the protocol.
## Contributing
Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.
Please make sure to update tests as appropriate.
## License
[Apache License 2.0](https://choosealicense.com/licenses/apache-2.0/)