Authentication Example
==============================================

This example illustrates a simple JWT-based authentication implementation in gRPC using
 server interceptor. It uses the JJWT library to create and verify JSON Web Tokens (JWTs).

The example requires grpc-java to be pre-built. Using a release tag will download the relevant binaries
from a maven repository. But if you need the latest SNAPSHOT binaries you will need to follow
[COMPILING](../../COMPILING.md) to build these.

The source code is [here](src/main/java/io/grpc/examples/jwtauth). 
To build the example, run in this directory:
```
$ ../gradlew installDist
```
The build creates scripts `auth-server` and `auth-client` in the `build/install/example-jwt-auth/bin/` directory 
which can be used to run this example. The example requires the server to be running before starting the
client.

Running auth-server is similar to the normal hello world example and there are no arguments to supply:

**auth-server**:

The auth-server accepts optional argument for port on which the server should run:

```text
USAGE: auth-server [port]
```

The auth-client accepts optional arguments for server-host, server-port, user-name and client-id:

**auth-client**:

```text
USAGE: auth-client [server-host [server-port [user-name [client-id]]]]
```

The `user-name` value is simply passed in the `HelloRequest` message as payload and the value of
`client-id` is included in the JWT claims passed in the metadata header.


#### How to run the example:

```bash
# Run the server:
./build/install/example-jwt-auth/bin/auth-server 50051
# In another terminal run the client
./build/install/example-jwt-auth/bin/auth-client localhost 50051 userA clientB
```

That's it! The client will show the user-name reflected back in the message from the server as follows:
```
INFO: Greeting: Hello, userA
```

And on the server side you will see the message with the client's identifier:
```
Processing request from clientB
```

## Maven

If you prefer to use Maven follow these [steps](../README.md#maven). You can run the example as follows:

```
$ # Run the server
$ mvn exec:java -Dexec.mainClass=io.grpc.examples.authentication.AuthServer -Dexec.args="50051"
$ # In another terminal run the client
$ mvn exec:java -Dexec.mainClass=io.grpc.examples.authentication.AuthClient -Dexec.args="localhost 50051 userA clientB"
```