I have hosted 3 microservices in PCF. One is a eureka server and the other 2 are client and service microservices. The client is supposed to call the service through a rest template call and service will return a string.
I have 1 instance each of the eureka server and the client and 2 instances of the service.
I can see both my client and service registered in the Eureka dashboard. But when i try to access the service from the client[Using a rest template call] I get - 'No instances available for the [service name]'
But if i access my service directly from browser then its works fine and returns the string. But the same URL if called from a rest template returns the exception i mentioned above.
Any suggestions will help
Did you add the #LoadBalance on restTemplate bean.
#Bean
#LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}
And when calling service you have to use the service name as below.
https://SERVICENAME/restpath
Related
I have an api gateway and a microservice. I have incorporated Spring cloud sleuth in my project but I am getting the incorrect Trace IDs. For example, if the gateway calls a microservice, both of them are supposed to have the same traceId but this is what I get -
API Gateway Logs
2021-06-22 11:00:13.446 INFO [gateway, 3ad39a60c4ac0e95, 3ad39a60c4ac0e95] 776 [ctor-http-nio-2] c.m.c.u.config.APIRoutes Locator : Routes are
Microservice Logs
2021-06-22 11:00:34.285 INFO [service1, 2a758b1cb504ca75,62e0509ed861a50f, true] 556 [nio-8000-exec-5] c.m.c.u.service.MasterReport Service: Fetching latest business date
I get a completely new TraceId in the microservice and I do not know from where that one originates.
So now, I was wondering whether it is possible to send the traceID from the gateway to the microservice so that I can replace the one that's showing up in the logs...
How do you contact another service? via http request? If so, try defining a RestTemplate bean in the class where you perform template.exchange(...), it solved the problem for me:
// Define this bean in some config class or directly in controller
#Bean
public RestTemplate template() {
return new RestTemplate();
}
// And autowire it in the controller class
#Autowired
private RestTemplate template;
public String call() {
return template.exchange(...);
How do I make Spring Boot Zuul Proxy Server handle a specific request locally, instead of proxying it to some other Server?
Let's say I want to do a custom health check of Zuul Proxy Server itself through an API which should return a local response, instead of returning a proxied response from some other remote server.
What kind of route configuration is required to forward the request?
Following is what I figured out and it worked for me:
1) Create a local request handler:
Add a regular Controller/RestController with a RequestMapping in a file in Zuul proxy Server code
#RestController
public class LocalRequestHandler {
#GetMapping(path = "/status", produces = MediaType.TEXT_PLAIN_VALUE);
private static ResponseEntity<String> getServiceStatus() {
String status = "I am alive";
return ResponseEntity.ok().body(status);
}
}
2) Create a local forwarding route in the configuration file (application.properties or as the case may be) where other routes are defined. In my case, Spring Boot Zuul Proxy server is running on Jetty container with GatewaySvc as the application context.
zuul.routes.gatewaysvc.path=/GatewaySvc/status
zuul.routes.gatewaysvc.url=forward:/GatewaySvc/status
For a standalone Spring Boot, which I have not tested, you may have to remove the context path from the above configuration.
zuul.routes.gatewaysvc.path=/status
zuul.routes.gatewaysvc.url=forward:/status
Reference:
Strangulation Patterns and Local Forwards
I have the following services:
EurekaServer - hosts the eureka discovery server
Client-service - registers to EurekaServer
Finder-service - registers to EurekaServer
Is there a way to get Client-service's ip so I can make requests to it from the Finder-service.
I know there is a way to find InstanceInfo from EurekaServer and I was thinking of making a controller in eureka server where you pass service id and get service's instance ip. This way Finder-service would only need to know service id and eureka ip which it knows because it is registered there.
Is there another solution which is cleaner than this?
To use client discovery you first need to enable by adding either #EnableEurekaClient or #EnableDiscoveryClient to your #SpringBootApplication annotated class (or your specialized #Configuration).
Next to make use of the resolution of the actual service instance to use you need to create a RestTemplate which is load-balanced. This will add an interceptor which translates the service name into the ip-address / DNS name to send the request to (if multiple instances are found it will distribute the load between those instances).
To create a load balanced RestTemplate add the #LoadBalanced annotation to the configured RestTemplate.
#Bean
#LoadBalanced
public RestTemplate restTemplate(RestTemplateBuilder rtb) {
return rtb.build();
}
Now when doing a request through the RestTemplate it will resolve the service name client-service to the actual service instance to use. Without you having to do anything.
In our project we use Spring cloud + Eureka as service registry.
When we use the ribbon client to call internal micro-services, all URL are resolved via Eureka ... that's a problem to call external URLs.
As external API are old fashioned usage of Feign doesn't seem to be good choice.
What's the best way to call an external URL from such a service ?
Thanks in advance
Patrice
One way working:
Use two configurations.
Declare your RestTemplate Bean to call external services like this:
#Primary
#Qualifier("withoutEureka")
#Bean
public RestTemplate restTemplate(){
...
}
Inject this reference in your client this way
#Bean
public MyClientForExtCall myClientForExtCall(#Qualifier("withoutEureka")RestTemplate restTemplate)
In the other configuration use the restTemplate as usual, but don't forget to use another qualifier
#LoadBalanced
#Bean
#Qualifier("withEureka")
public RestTemplate loadBalancedEureka(){
...
}
#Bean
public MyClientForInternal myClientForInternal(#Qualifier("withoutEureka")RestTemplate restTemplate)
Patrice
You can use Ribbon without Eureka. For external APIs where you cannot configure in Eureka to abstract the discover. You can hard code their URLs in client and configure server list. The Ribbon client defaults to a configured server list, and you can supply the configuration like this:
stores:
ribbon:
listOfServers: example.com, google.com
According to this blog https://spring.io/blog/2015/07/14/microservices-with-spring
Was able to run the application without any issues. In this order:
java -jar microservice-demo-0.0.1-SNAPSHOT.jar registration 1111
java -jar microservice-demo-0.0.1-SNAPSHOT.jar accounts 2222
java -jar microservice-demo-0.0.1-SNAPSHOT.jar web 3333
But when trying to hit any service through the web application (http://localhost:3333/) which uses the http://ACCOUNTS-SERVICE url to access any accounts service endpoints like http://ACCOUNTS-SERVICE/accounts/123456789 I'm getting an error response:
Response Status: 500 (Internal Server Error)
Cause: org.springframework.web.client.ResourceAccessException I/O error on GET request for "http://ACCOUNTS-SERVICE/accounts/123456789": ACCOUNTS-SERVICE; nested exception is java.net.UnknownHostException: ACCOUNTS-SERVICE
When I provide the real address (http://localhost:2223/) of the accounts service to the web server instead of the http://ACCOUNTS-SERVICE everything works properly but there is no service discovery in this case.
The source code is stored at: https://github.com/paulc4/microservices-demo
This issue was due to the RestTemplate was no longer auto-created in the Brixton release-train (Spring Cloud 1.1.0.RELEASE), so the RestTemplate could not resolve properly the http://ACCOUNTS-SERVICE url using the service discovery server.
Was able to fix this issue after declaring a RestTemplate bean with #LoadBalanced as follows:
#Bean
#LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}