Using gRPC, a client application can directly call methods on a server application as if it was a local object. The schema for Dex's gRPC API calls is defined in [`api/api.proto`][api-proto]. [`client.go`][client] is an example client program that makes a bunch of API calls to the dex server. For further details on the Dex API refer [`Documentation/api.md`][api-docs].
## Generating Credentials
Before running the client or the server, TLS credentials have to be setup for secure communication. Run the `cred-gen` script to create TLS credentials for running this example. This script generates a `ca.crt`, `server.crt`, `server.key`, `client.crt`, and `client.key`.
```
# Used to set certificate subject alt names.
export SAN=IP.1:127.0.0.1
# Run the script
./examples/grpc-client/cert-gen
```
To verify that the server and client certificates were signed by the CA, run the following commands:
```
openssl verify -CAfile ca.crt server.crt
openssl verify -CAfile ca.crt client.crt
```
## Running the Dex server
To expose the gRPC service, the gRPC option must be enabled via the dex config file as shown below.
```yaml
# Enables the gRPC API.
grpc:
addr: 127.0.0.1:5557
tlsCert: server.crt
tlsKey: server.key
```
Start an instance of the dex server with an in-memory data store:
```
./bin/dex serve examples/grpc-client/config.yaml
```
## Running the Dex client
Finally run the Dex client providing the CA certificate, client certificate and client key as arguments.
