service to service authentication with Spring cloud Oauth 2 - spring-boot

Question

I'm using multiple microservices with Spring Cloud stack and oauth2 is used to protect resources and provide SSO.
I'm able to authenticate from a user interface with login and password.
But i also need to call a service from another service. My issue is that the service need to be authenticate. This kind of call:
ResponseEntity<String> responseEntity = restTemplate.exchange("http://anoter-service/hello", HttpMethod.GET, null, new ParameterizedTypeReference<String>() {});
Any idea on how to authenticate a service calling another one ?
I have this exception:
Caused by: org.springframework.security.oauth2.client.resource.UserRedirectRequiredException: A redirect is required to get the users approval
at org.springframework.security.oauth2.client.token.grant.code.AuthorizationCodeAccessTokenProvider.getRedirectForAuthorization(AuthorizationCodeAccessTokenProvider.java:359)
at org.springframework.security.oauth2.client.token.grant.code.AuthorizationCodeAccessTokenProvider.obtainAccessToken(AuthorizationCodeAccessTokenProvider.java:205)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.acquireAccessToken(OAuth2RestTemplate.java:221)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.getAccessToken(OAuth2RestTemplate.java:173)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.createRequest(OAuth2RestTemplate.java:105)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:592)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.doExecute(OAuth2RestTemplate.java:128)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:557)
at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:503)
at org.springframework.web.client.RestTemplate$$FastClassBySpringCGLIB$$aa4e9ed0.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:720)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:85)
at org.springframework.cloud.netflix.metrics.RestTemplateUrlTemplateCapturingAspect.captureUrlTemplate(RestTemplateUrlTemplateCapturingAspect.java:33)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:620)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:609)
at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:68)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:655)
at org.springframework.security.oauth2.client.OAuth2RestTemplate$$EnhancerBySpringCGLIB$$3473d19a.exchange(<generated>)

Answer 1

I would just log in programatically through the same authentication entry point your users do. Create credentials for your services and set their permissions in this area. I don't think you should try to treat your services any differently.
You will likely have to set up your rest template to watch for 403s and when encountered perform a log in, but that should be fairly easy to code.