In this article, I’m going to show you how to bootstrap a local kubernetes cluster with a custom image, debug it, deploy a new image, then rollback to the old image.

There is some [hacky] code for this post on Github.

The number of hystrix configuration options, as of this writing, is about 34. In reality, you don’t need to worry about most of them, as the defaults are perfectly reasonable. This article discusses those parameters that, in my experience, you typically need to pay attention to and tune, and I have provided some examples using spring boot’s support for hystrix via the javanica library.

You can see the source code for this post on Github.

Following up on the last post [ How to Expose Meaningful Prometheus Metrics In a Spring Boot 2.x Application], if we have metrics exposed but they don’t go anywhere, are there metrics exposed at all?

The source code for this post can be found on Github.

Prometheus is a metrics aggregator with its own presumed format. The basic idea is to have the application gather a set of custom metrics, then periodically collect (or “scrape”) the metrics and send them off to a prometheus server. This server will store the data in its database, and you can thus view the evolution of your application’s metrics over time.

Reactive Programming is a very different way of thinking about doing work in a microservices environment. Anyone who has worked with a GUI, dating back to even to windows forms, is familiar with the event based model, but what does that mean when there is unpredictable latency involved? How does handing off to a thread to make a remote call differ from this new “reactive web”?

Spring Boot’s WebFlux programming model is pretty neat, but there isn’t a lot by way of explaining how to best leverage it to get the results you need. I wrote this blog post after tinkering with the configuration of Reactor Netty on Spring Boot.

The source code for this post can be found on GitHub.

When you’re in a microservice environment, it often makes sense to make some calls to multiple services at the same time. This allows for the time an operation needs to complete to be reduced from the sum of all the time spent waiting to the maximum time spent over the span of calls.

havent written it

In a previous post, we saw how to provision a simple consul client/server cluster using Ansible. We will now look at interacting with that cluster by showing how to register a spring boot application to it, using spring cloud consul.

A single page application (SPA) architecture usually involves an end user getting a smattering of javascript files when he/she makes a request to a URL endpoint. After the javascript files load and start executing code, they usually make AJAX calls to interact with the back end from that point onwards. This pairs nicely with a microservice architecture based on REST over HTTP, since the front end SPA can effectively act as a client to any microservice that it needs information from.

You can see the source code for this post on GitHub.

We spent the last post figuring out how to migrate an embedded PostgreSQL database using Spring, while trying to side-step the extra magic that comes along with the framework. Here, we are going to build on that work to migrate a real PostgreSQL instance, which we will build in a local Vagrant Virtual Machine.

The source code for this post can be found on GitHub.

Flyway is a database migration tool. Migrating a database generally means that you are making a change to the way the database currently structures its data. It could also mean you are adding stuff like custom stored procedures or indexes to help speed up queries. Either way, migrating databases is easily the most difficult part of any deployment strategy–Flyway makes this process as painless as possible because it will, by default, only run migration scripts that haven’t yet run.