microservices | Example of building microservices with Kotlin | Microservice library

let's assume this is my folder structure with all microservices and all package.json have start, dev and test scripts defined.

Context:

1. In Azure function with EventHubTrigger, I save data mapped from handled event to database (through the Entity framework). This action performs synchronously
2. Trigger a new event about successful data insertion using event hub producer. This action is async
3. Handle that triggered event at some other place

I guess it might happen that something fails during saving data, so I am wondering how to prevent inconsistency and secure that event is not sent if it should not. As far as I know Azure Event Hub has no outbox pattern implemented yet, so I guess I would need to mimic it somehow.

I am also thinking about alternative and a bit smelly solution to make this publish event method synchronous in step 2 (even if nature of the event-driven is to be async) and to add an addition check between step 1 and step 2 - to make sure that everything is saved in db. Only if that condition is fulfilled, event is going to be triggered (step 3).

Any advice?

I have 3 AWS Elastic Beanstalk instances which are running Spring microservices. All microservices are making POST requests to each other and using RDS service for database.

Should I isolate database traffic and microservices traffic into separate subnets? In case it's a good practice is it possible to assign 2 private network IP's for each subnet for every AWS Elastic Beanstalk instance?

Trying to understand event driven microservices; like in this video. It seems like the basic idea is "producers create tasks that change the state of a system. Consumers read all relevant tasks (from whatever topic they care about) and make decisions off that"

So, if I had a system of jars- say a red, blue, and green jar (topics). And then had producers adding marbles to each jar (deciding color based on random number, let's say). The producers would tell kafka "add a marble to red. Add a marble to blue... etc" Then, the consumers, every time we wanted to count jars would get the entire log and say "ok, a marble was added to red, so redCount++, then a marble was added to blue so blueCount++..." for the dozens/hundreds/thousands of lines that the log file takes up?

That can't be correct; I know it can't be correct. It seems incredibly inefficient; almost anti-efficient!

What am I missing in my knowledge of kafka tasks?

We have several microservices built on top of aspnetcore and entity framework and using the MySQL EntityFramework connector from Devart. I've noticed that if the first query that any of our applications attempts fails due to the data store being inaccessible, then the failure seems to be cached, and when the DB is finally alive, the exception is still returned to the user code.

As part of the diagnosis of this problem I tried disabling the database when the application is running and in this situation the application appears to be able to recover once the DB is available again, so I suspect the problem is related to a connection that may be cached during model initialisation.

I've also tried disabling the service provider caching and this also lets the application recover but at the cost of having to initialise the service provider each time, so this can't be used in our application but lends weight to the idea that the error is related to some form of caching.

Has anyone else had/seen this problem before? What was your solution?

Here is a stack trace for context:

I use a large RDS database instance that is shared among several different projects (not microservices to be exact) and this database's performance is critical. Hence I monitor the queries whenever support team raise tickets related to performance of our services. So in order for me to track where each query originated from i.e, which app, file and line number, I want to automatically add a SQL comment for all queries. So when I call toSql() on the query builder object it must show me the comment

I'm currently working on a microservices application for my internship using Consul for service discovery and feign clients for communicating between the services. When we started working on the existing project which already was built using microservices, we upgraded Spring boot to 2.4.3 & cloud to 2020.0.1, so that we could make use of Java 15 to use records instead of normal classes for dtos. The problem we have now is that, whenever we make a call to a composite service, that will try to retrieve data from multiple services (for example users and teams service), that we get the following stacktrace:

I'm trying to build sample Service Registration Server using Kotlin & Gradle, when i deploy it locally using intelliJ everything works fine, but when I try to pack it up into docker and launch container I get this:

I have successfully exposed two microservices on AWS with Traefik Ingress Controller and AWS HTTPS Load Balancer on my registered domain.

Here is the source code: https://github.com/skyglass-examples/user-management-keycloak

I can easily access both microservices with https url: