gRPC service implementations exposed as CDI beans are automatically registered and served by quarkus-grpc.
Implementing a gRPC service requires the gRPC classes to be generated.
Place your proto files in src/main/proto and run mvn compile .
|
Generated Code
Quarkus generates a few implementation classes for services declared in the proto
file:
-
A service interface using the Mutiny API
-
the class name is
${JAVA_PACKAGE}.${NAME_OF_THE_SERVICE}
-
-
An implementation base class using the gRPC API
-
the class name is structured as follows:
${JAVA_PACKAGE}.${NAME_OF_THE_SERVICE}Grpc.${NAME_OF_THE_SERVICE}ImplBase
-
For example, if you use the following proto
file snippet:
option java_package = "hello"; (1)
service Greeter { (2)
rpc SayHello (HelloRequest) returns (HelloReply) {}
}
1 | hello is the java package for the generated classes. |
2 | Greeter is the service name. |
Then the service interface is hello.Greeter
and the implementation base is the abstract static nested class: hello.GreeterGrpc.GreeterImplBase
.
You’ll need to implement the service interface or extend the base class with your service implementation bean as described in the following sections. |
Implementing a Service with the Mutiny API
To implement a gRPC service using the Mutiny API, create a class that implements the service interface.
Then, implement the methods defined in the service interface.
If you don’t want to implement a service method just throw an java.lang.UnsupportedOperationException
from the method body (the exception will be automatically converted to the appropriate gRPC exception).
Finally, implement the service and add the @GrpcService
annotation:
import io.quarkus.grpc.GrpcService;
import hello.Greeter;
@GrpcService (1)
public class HelloService implements Greeter { (2)
@Override
public Uni<HelloReply> sayHello(HelloRequest request) {
return Uni.createFrom().item(() ->
HelloReply.newBuilder().setMessage("Hello " + request.getName()).build()
);
}
}
1 | A gRPC service implementation bean must be annotated with the @GrpcService annotation and should not declare any other CDI qualifier. All gRPC services have the javax.inject.Singleton scope. Additionally, the request context is always active during a service call. |
2 | hello.Greeter is the generated service interface. |
The service implementation bean can also extend the Mutiny implementation base, where the class name is structured as follows: Mutiny${NAME_OF_THE_SERVICE}Grpc.${NAME_OF_THE_SERVICE}ImplBase .
|
Implementing a Service with the default gRPC API
To implement a gRPC service using the default gRPC API, create a class that extends the default implementation base.
Then, override the methods defined in the service interface.
Finally, implement the service and add the @GrpcService
annotation:
import io.quarkus.grpc.GrpcService;
@GrpcService
public class HelloService extends GreeterGrpc.GreeterImplBase {
@Override
public void sayHello(HelloRequest request, StreamObserver<HelloReply> responseObserver) {
String name = request.getName();
String message = "Hello " + name;
responseObserver.onNext(HelloReply.newBuilder().setMessage(message).build());
responseObserver.onCompleted();
}
}
Blocking Service Implementation
By default, all the methods from a gRPC service run on the event loop.
As a consequence, you must not block.
If your service logic must block, annotate the method with io.smallrye.common.annotation.Blocking
:
@Override
@Blocking
public Uni<HelloReply> sayHelloBlocking(HelloRequest request) {
// Do something blocking before returning the Uni
}
Handling Streams
gRPC allows receiving and returning streams:
service Streaming {
rpc Source(Empty) returns (stream Item) {} // Returns a stream
rpc Sink(stream Item) returns (Empty) {} // Reads a stream
rpc Pipe(stream Item) returns (stream Item) {} // Reads a streams and return a streams
}
Using Mutiny, you can implement these as follows:
import io.quarkus.grpc.GrpcService;
@GrpcService
public class StreamingService implements Streaming {
@Override
public Multi<Item> source(Empty request) {
// Just returns a stream emitting an item every 2ms and stopping after 10 items.
return Multi.createFrom().ticks().every(Duration.ofMillis(2))
.select().first(10)
.map(l -> Item.newBuilder().setValue(Long.toString(l)).build());
}
@Override
public Uni<Empty> sink(Multi<Item> request) {
// Reads the incoming streams, consume all the items.
return request
.map(Item::getValue)
.map(Long::parseLong)
.collect().last()
.map(l -> Empty.newBuilder().build());
}
@Override
public Multi<Item> pipe(Multi<Item> request) {
// Reads the incoming stream, compute a sum and return the cumulative results
// in the outbound stream.
return request
.map(Item::getValue)
.map(Long::parseLong)
.onItem().scan(() -> 0L, Long::sum)
.onItem().transform(l -> Item.newBuilder().setValue(Long.toString(l)).build());
}
}
Health Check
For the implemented services, Quarkus gRPC exposes health information in the following format:
syntax = "proto3";
package grpc.health.v1;
message HealthCheckRequest {
string service = 1;
}
message HealthCheckResponse {
enum ServingStatus {
UNKNOWN = 0;
SERVING = 1;
NOT_SERVING = 2;
}
ServingStatus status = 1;
}
service Health {
rpc Check(HealthCheckRequest) returns (HealthCheckResponse);
rpc Watch(HealthCheckRequest) returns (stream HealthCheckResponse);
}
Clients can specify the fully qualified service name to get the health status of a specific service or skip specifying the service name to get the general status of the gRPC server.
For more details, check out the gRPC documentation
Additionally, if Quarkus SmallRye Health is added to the application, a readiness check for
the state of the gRPC services will be added to the MicroProfile Health endpoint response, that is /q/health
.
Reflection Service
Quarkus gRPC Server implements the reflection service. This service allows tools like grpcurl or grpcox to interact with your services.
The reflection service is enabled by default in dev mode.
In test or production mode, you need to enable it explicitly by setting quarkus.grpc.server.enable-reflection-service
to true
.
Scaling
By default, quarkus-grpc starts a single gRPC server running on a single event loop.
If you wish to scale your server, you can set the number of server instances by setting quarkus.grpc.server.instances
.
Server Configuration
Configuration property fixed at build time - All other configuration properties are overridable at runtime
Type |
Default |
|
---|---|---|
The gRPC Server port. |
int |
|
The gRPC Server port used for tests. |
int |
|
The gRPC server host. |
string |
|
The gRPC handshake timeout. |
||
The max inbound message size in bytes. |
int |
|
The max inbound metadata size in bytes |
int |
|
The classpath path or file path to a server certificate or certificate chain in PEM format. |
path |
|
The classpath path or file path to the corresponding certificate private key file in PEM format. |
path |
|
An optional key store which holds the certificate information instead of specifying separate files. The key store can be either on classpath or an external file. |
path |
|
An optional parameter to specify the type of the key store file. If not given, the type is automatically detected based on the file name. |
string |
|
A parameter to specify the password of the key store file. If not given, the default ("password") is used. |
string |
|
An optional trust store which holds the certificate information of the certificates to trust The trust store can be either on classpath or an external file. |
path |
|
An optional parameter to specify type of the trust store file. If not given, the type is automatically detected based on the file name. |
string |
|
A parameter to specify the password of the trust store file. |
string |
|
The cipher suites to use. If none is given, a reasonable default is selected. |
list of string |
|
The list of protocols to explicitly enable. |
list of string |
|
Configures the engine to require/request client authentication. NONE, REQUEST, REQUIRED |
|
|
Disables SSL, and uses plain text instead. If disabled, configure the ssl configuration. |
boolean |
|
Whether ALPN should be used. |
boolean |
|
The path to the certificate file. |
string |
|
The path to the private key file. |
string |
|
Enables the gRPC Reflection Service. By default, the reflection service is only exposed in |
boolean |
|
Number of gRPC server verticle instances. This is useful for scaling easily across multiple cores. The number should not exceed the amount of event loops. |
int |
|
Sets a custom keep-alive duration. This configures the time before sending a |
||
gRPC compression, e.g. "gzip" |
string |
About the Duration format
The format for durations uses the standard You can also provide duration values starting with a number.
In this case, if the value consists only of a number, the converter treats the value as seconds.
Otherwise, |
Example of Configuration
Enabling TLS
To enable TLS, use the following configuration.
Note that all paths in the configuration may either specify a resource on the classpath
(typically from src/main/resources
or its subfolder) or an external file.
quarkus.grpc.server.ssl.certificate=tls/server.pem
quarkus.grpc.server.ssl.key=tls/server.key
When SSL/TLS is configured, plain-text is automatically disabled.
|
TLS with Mutual Auth
To use TLS with mutual authentication, use the following configuration:
quarkus.grpc.server.ssl.certificate=tls/server.pem
quarkus.grpc.server.ssl.key=tls/server.key
quarkus.grpc.server.ssl.trust-store=tls/ca.jks
quarkus.grpc.server.ssl.trust-store-password=*****
quarkus.grpc.server.ssl.client-auth=REQUIRED
Server Interceptors
You can implement a gRPC server interceptor by implementing an @ApplicationScoped
bean implementing io.grpc.ServerInterceptor
:
@ApplicationScoped
public class MyInterceptor implements ServerInterceptor {
@Override
public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(ServerCall<ReqT, RespT> serverCall,
Metadata metadata, ServerCallHandler<ReqT, RespT> serverCallHandler) {
// ...
}
}
Check the ServerInterceptor JavaDoc to properly implement your interceptor. |
When you have multiple server interceptors, you can order them by implementing the javax.enterprise.inject.spi.Prioritized
interface:
source, java]
@ApplicationScoped public class MyInterceptor implements ServerInterceptor, Prioritized { @Override public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(ServerCall<ReqT, RespT> serverCall, Metadata metadata, ServerCallHandler<ReqT, RespT> serverCallHandler) { // ... } @Override public int getPriority() { return 10; } }
Interceptors with the highest priority are called first.
The default priority, used if the interceptor does not implement the Prioritized
interface, is 0
.