How can we use grcp communication with spring boot application. And how we can use common service discovery method for use with grpc to get end point of spring boot application.
For service discovery, implement your own NameResolver.
I used below code to get instance discovery client. It help to call all servers using revers poxing.
#Autowired
private DiscoveryClient discoveryClient;
and below method help to call all the services using service name
#RequestMapping(method = RequestMethod.GET, value = "/senduser")
public ResponseEntity<?> sendMessageToAllServices() {
user u=null;
List<ServiceInstance> server=discoveryClient.getInstances("grpc-server");
for (ServiceInstance serviceInstance : server) {
String hostName=serviceInstance.getHost();
int gRpcPort=Integer.parseInt(serviceInstance.getMetadata().get("grpc.port"));
ManagedChannel channel=ManagedChannelBuilder.forAddress(hostName,gRpcPort).usePlaintext(true).build();
UserServiceBlockingStub stub=UserServiceGrpc.newBlockingStub(channel);
UserDetail user=UserDetail.newBuilder()
.setName("Thamira")
.setEmail("Thamira1005#gmail.com")
.setAge(24).setGender(Gender.Male)
.setPassword("password").build();
u=stub.createUser(user);
}
return ResponseEntity.ok("User "+u);
}
we can change register as a consul or eureka. This method support both of that.
Related
We have a spring boot based application and using spring webflux, we are exposing 3 ports
server.port
management.server.port (actuator) and are planning to expose another port called as admin port.
We want to expose a specific REST controller on this admin port which will be private. This api will provide all the admin level configuration and will not be available publicly to the user.
Note: We don't want to expose api on actuator port. Need to open a new port.
Using the following code to open a new port by starting a new server instance.
#Configuration
public class NettyServerForAdminPort {
#Value("${admin.port}")
private Integer adminPort;
#Autowired
HttpHandler httpHandler;
WebServer http;
#PostConstruct
public void start() {
ReactiveWebServerFactory factory = new NettyReactiveWebServerFactory(8081);
this.http = factory.getWebServer(this.httpHandler);
this.http.start();
}
#PreDestroy
public void stop() {
this.http.stop();
}
}
Any insights on how this can be achieved?
I have installed an Eureka server and have registered a service called pricing-service.
The Eureka dashboard shows
UP pricing-service:4ac78ca47bdbebb5fec98345c6232af0
under status.
Now I have a completely separate Spring boot web service which calls (through a WebClient instance) the pricing-service as http://pricing-service but I get "reactor.core.Exceptions$ReactiveException: java.net.UnknownHostException: No such host is known (pricing-service)"
exception.
So the Controller can't find the pricing-service by hostname.Further, how is the controller aware of the Eureka server in order to get to pricing-service? Shouldn't there be a reference to it in the application.properties of the web service? I couldn't find anything around the web.
WebClient doesn't know anything about Eureka out of the box. You need to use #LoadBalancerClient and #LoadBalanced to wire it up through the load balancer. See the docs here:
https://spring.io/guides/gs/spring-cloud-loadbalancer/
Now I have a completely separate Spring boot web service which calls (through a WebClient instance) the pricing-service as http://pricing-service
This separate service (the WebClient Service) of yours must also register itself with Eureka Server.
By default, webclient is not aware of having to use load-balancer to make calls to other eureka instances.
Here is one of the ways to enable such a WebClient bean:
#Configuration
public class MyBeanConfig {
#Bean
WebClient webClient(LoadBalancerClient lbClient) {
return WebClient.builder()
.filter(new LoadBalancerExchangeFilterFunction(lbClient))
.build();
}
}
Then, you can use this webClient bean to make calls as:
#Component
public class YourClient {
#Autowired
WebClient webClient;
public Mono<ResponseDto> makeCall() {
return webClient
.get()
.uri("http://pricing-service/")
// <-- change your body and subscribe to result
}
Note: Initializing a Bean of WebClient can be explored further here.
I had the issue that WebClient was not working with #LoadBalanced for me when I created a bean that returned WebClient. You have to create a bean for WebClient.Builder instead of just WebClient, otherwise the #LoadBalanced annotation is not working properly.
#Configuration
public class WebClientConfig {
#Bean
#LoadBalanced
public WebClient.Builder loadBalancedWebClientBuilder() {
return WebClient.builder();
}
}
I want to use OAuth2 ClientCredentials flow for inter service communication between two Resource Servers. Everything works fine except that i am not able to use service name (Ribbon Load Balancer feature) instead of hostname in my OAuth2RestTemplate calls to remote resource server.
One of my Resource Server (that calls another Resource Server) has below configuration:
Spring Boot 1.5.13
Spring Cloud Edgware.SR3
build.gradle contains entries for eureka and ribbon
compile('org.springframework.cloud:spring-cloud-starter-ribbon')
compile('org.springframework.cloud:spring-cloud-starter-eureka')
#Configuration
class RestTemplateConfig {
#Bean
#ConfigurationProperties("security.oauth2.client")
public ClientCredentialsResourceDetails oauth2ClientCredentialsResourceDetails() {
return new ClientCredentialsResourceDetails();
}
#LoadBalanced
#Bean(name = "oauthRestTemplate")
public OAuth2RestOperations oAuthRestTemplate(ClientCredentialsResourceDetails oauth2ClientCredentialsResourceDetails) {
return new OAuth2RestTemplate(oauth2ClientCredentialsResourceDetails);
}
}
Service Consuming this OAuth2RestTemplate
#Service
class TestService {
#Autowired
#Qualifier("oauthRestTemplate")
private OAuth2RestOperations oAuth2RestOperations;
public void notifyOrderStatus(long orderId, OrderStatus newStatus) {
oAuth2RestOperations.exchange("http://notification-service/api/order/{id}/status/{status}", HttpMethod.POST, null, Void.class, orderId, newStatus.name());
}
}
Exception appears while invoking remote service using service name i.e. http://notification-service instead of actual hostname and port of remote resource server. If I use actual hostname + port, then everything works fine but I don't want my one resource to know host/post of another resource server.
Exception:
Caused by: java.net.UnknownHostException: notification-service
I have few questions:
If my RestTemplate is annotated with #LoadBalanced, then everything works fine. Does OAuth2RestTemplate support this annotation and can we use service name instead of hostname? If yes, any reference or documentation would be appreciated.
Is it a good idea to use oauth2 client credentials for inter service security between two resource servers? I do not see any samples for the same in documentation?
#LoadBalanced RestTemplate works when we use RestTemplateCustomizer to customize the newly created OAuth2RestTemplate, as shown in the below code:
#Bean(name = "MyOAuthRestTemplate")
#LoadBalanced
public OAuth2RestOperations restTemplate(RestTemplateCustomizer customizer, ClientCredentialsResourceDetails oauth2ClientCredentialsResourceDetails) {
OAuth2RestTemplate restTemplate = new OAuth2RestTemplate(oauth2ClientCredentialsResourceDetails);
customizer.customize(restTemplate);
return restTemplate;
}
Using service name instead of actual host name works fine using this RestTemplate.
I have a Spring boot application which uses Feign to call an external web service via Eureka. I'd like to be able to run the application using a mocked out implementation of the Feign interface, so I can run the application locally without necessarily having Eureka or the external web service running. I had imagined defining a run configuration that allowed me to do this, but am struggling to get this working. The issue is that the Spring "magic" is defining a bean for the Feign interface no matter what I try.
Feign interface
#FeignClient(name = "http://foo-service")
public interface FooResource {
#RequestMapping(value = "/doSomething", method = GET)
String getResponse();
}
Service
public class MyService {
private FooResource fooResource;
...
public void getFoo() {
String response = this.fooResource.getResponse();
...
}
}
I tried adding a configuration class that conditionally registered a bean if the Spring profile was "local", but that was never called when I ran the application with that Spring profile:
#Configuration
public class AppConfig {
#Bean
#ConditionalOnProperty(prefix = "spring.profile", name = "active", havingValue="local")
public FooResource fooResource() {
return new FooResource() {
#Override
public String getResponse() {
return "testing";
}
};
}
}
At the point my service runs, the FooResource member variable in MyService is of type
HardCodedTarget(type=FoorResource, url=http://foo-service)
according to IntelliJ. This is the type that is automatically generated by the Spring Cloud Netflix framework, and so tries to actually communicate with the remote service.
Is there a way I can conditionally override the implementation of the Feign interface depending on a configuration setting?
the solution is like below:
public interface FeignBase {
#RequestMapping(value = "/get", method = RequestMethod.POST, headers = "Accept=application/json")
Result get(#RequestBody Token common);
}
then define your env based interface:
#Profile("prod")
#FeignClient(name = "service.name")
public interface Feign1 extends FeignBase
{}
#Profile("!prod")
#FeignClient(name = "service.name", url = "your url")
public interface Feign2 extends FeignBase
{}
finally, in your service impl:
#Resource
private FeignBase feignBase;
Having posted the same question on the Spring Cloud Netflix github repository, a useful answer was to use the Spring #Profile annotation.
I created an alternative entry point class that was not annotated with #EnabledFeignClients, and created a new configuration class that defined implementations for my Feign interfaces. This now allows me to run my application locally without the need to have Eureka running, or any dependent services.
I'm using a simpler solution to avoid having multiples interfaces for a variable parameter like url.
#FeignClient(name = "service.name", url = "${app.feign.clients.url}")
public interface YourClient{}
application-{profile}.properties
app.feign.clients.url=http://localhost:9999
I have developed a REST server with our app specific APIs. we also have deployed a different rest Job server into another location. Currently the way I am doing is .
#RestController
public class SparkJobController {
#Autowired
private IJobSchedulerService jobService;
...
And the Service Implementation is
#Service(value="jobService")
public class JobSchedulerServiceImpl implements IJobSchedulerService {
#Override
public Map triggerJob(String context) {
Map<String, ?> s = new HashMap<String,Object>();
RestTemplate restTemplate = new RestTemplate();
// restTemplate call to other REST API. and returns Map.
...
}
My question is , Is my approach correct ? Or Does Spring framework enables us to use some predefined APIs which can help to use RESTTemplate as a Service
[EDIT] : the deployed REST service is third party application.
I did some research and havent' seen yet a way to implement RestTemplate as a service.
I have seen RestTemplate defined in the bean config and auto wired in - https://www.informit.com/guides/content.aspx?g=java&seqNum=546
To summarize, most of the examples I have seen use Resttemplate, similar to how you have implemented in your code.