I am following a micro-service based architecture for my service development. I want to trace each of my request through various microservice calls in my system. My microservices are communicating over Google PubSub messaging framework. I am not able to find any out of the box way to pass on the MDC context to my subsequent service calls. I am using spring Sleuth for tracing. Is there any way I can pass the MDC context over PubSub calls?
If by "MDC" you mean tracing context then you can e.g. use Spring Cloud Stream with Google PubSub that would work out of the box. If you need to do it manually then you can access the current span from the Tracer bean, via tracer.currentSpan() and from its SpanContext you can retrieve the trace id and span id that you should pass to the Google PubSub message.
Related
Following documentation, there are multiple ways to integrate Google Cloud PubSub events with Spring application:
Spring Cloud GCP has several modules for sending messages to Pub/Sub
topics and receiving messages from Pub/Sub subscriptions using the
Spring Framework. You can use these modules independently or combine
them for different use cases:
Spring Cloud GCP Pub/Sub Starter lets you send and receive messages
using helper classes and call the Pub/Sub Java client library for more
advanced scenarios.
Spring Integration Channel Adapters for Pub/Sub
let you connect Spring Integration Message Channels with Pub/Sub.
Spring Cloud Stream Binder for Pub/Sub lets you use Pub/Sub as
messaging middleware in Spring Cloud Stream applications.
I don't have full understanding - what are those different use cases mentioned, and how to determine, which module is best for which use case?
Application (Dockerized Spring Boot app, deployed to Kubernetes in GCP) I am working on is rather simple, it is expected to act upon received PubSub event, it is not going to publish any events itself.
Spring Cloud GCP Pub/Sub Starter module contains the java client classes for pub sub which will be used by your spring application to perform administrative and functional operations (ie. sending and receiving messages).
Spring Integration Channel Adapters for Pub/Sub module is utilized when your spring application uses Message Channels. This module will help routing message between message channel and pub/sub using channel adapters.
Spring Cloud Stream Binder for Pub/Sub module is used in Spring Cloud Stream Applications in order to utilize cloud Pub/Sub API.
Since, your application requirements are basic you can easily go for Spring Cloud GCP Pub/Sub Starter module. For more information you can refer to this Google documentation.
We want to build a rest API to service high request volumes. I'm planning to build it using Spring Reactive(WebFlux) or using Spring Boot Async. We have multiple different clients who will be invoking our service.
Do I need to worry about different clients who will be consuming this service? Meaning if I build the API using Reactive or Async, will all the clients be able to consume this seemlessly?
Meaning if build a reactive Rest API, will the client using RestTemplate be able to consume or do they need to use WebClient only?
Yes, your (not non blocking) clients will still be able to consume a reactive service.
I'm running a Spring Boot app using:
Spring Boot 2.3.8
Spring Cloud Hoxton.SR10
I've declared the spring-cloud-starter-zipkin and spring-cloud-starter-openfeign dependencies, and have configured my app to point to a Zipkin server. Its a pretty vanilla setup and configuration (I also declare the spring-cloud-starter-netflix-ribbon and spring-cloud-starter-kubernetes-all dependencies o allow Spring Feign to use k8s service discovery).
My app declares a #SpringFeign annotated interface with a method to call to a remote service S.
So generally zipkin is getting spans from my app (for e.g. incoming REST calls) and B3 headers are being propagated via HTTP to the service S being called through feign.
But zipkin does not report a span from my app representing the Feign call to S.
Is that something that should "just happen", or am I missing a piece of the puzzle?
I can e.g. add #NewSpan to the feign interface method, but that doesn't give me HTTP details for the request/response as span tags. And I rather not do that if this is supposed to work out of the box.
This should be done out of the box: https://docs.spring.io/spring-cloud-sleuth/docs/2.2.7.RELEASE/reference/html/#feign
You can take a look at the feign sample (you need to go back in the history, currently it is for 3.x): https://github.com/spring-cloud/spring-cloud-sleuth/tree/master/spring-cloud-sleuth-samples/spring-cloud-sleuth-sample-feign
In order to see if propagation works, look into the outgoing request, it should contain the tracing-related headers.
I have created topic and subscription in google pubsub. How to read the google pub sub message from spring boot application(Subscriber? Also how to make always listening that subscription from my application to pull/read the message.
I would strongly recommend you to take a look at Spring Cloud GCP. It features a Pub/Sub integration that should be just what you're looking for.
There's a sample application here.
I have a spring mvc application which runs correctly,now another colleague wants to call the same functions from another application but he needs REST URL of my functions.
how is it possible to provide the same functionality through spring REST?
is it just with new annotations .please provide some resource to show me how to do it.
when server has a service, only legal clients which had any contracts with server can access it. And clients can use service by the way such as: use RestTemplate to get/post request to URL of service, and clients can get data as JSON, or XML type if you have an equivalent object as this image:
Also, a service can be support as a interface, ex: google search is a service supported by google, but it's not rest service.
If you know each other URL address you can consume each other REST API from java code by using RestTemplate object.
I would advise you to go over the Spring starter guide which deals with that issue, here is the link (Consuming a RESTful Web Service):
https://spring.io/guides/gs/consuming-rest/