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| Photo of two elephants friendly interacting with each other, from The Scientific American: Fact or Fiction?: Elephants Never Forget |
This post discusses the stateless microservice design pattern; it is meant as support material for other posts of mine that discuss microservices, mainly michael.gr - The Stateful Microservice.
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| Dory, the yellow-blue fish (a Royal Blue Tang) that suffered from amnesia in the 2003 movie Finding Nemo by Pixar. |
Even if you disagree with the terseness of that definition, and you regard microservices as necessarily more than that, I hope you will at least agree that it is precisely scalability and resilience that the stateless microservice design pattern aims to address, so the definition serves its purpose at least in the context of this series of posts.
There are many who will try to convince you that in order to build a scalable and resilient system, you need statelessness; so much so, that microservices have almost come to be regarded as synonymous with statelessness. This post examines whether this is that in fact so, and what is the cost of doing things this way.
This article attempts to shed some light on what a microservice really is; it is meant as support material for other posts of mine that discuss microservices, mainly michael.gr - The Stateful Microservice.
If you go looking for information out there, you will find many different descriptions of what a microservice is; these descriptions exhibit considerable difference of opinion, and to the extent that they agree, it is largely the result of copy-paste. One common theme in these descriptions is that in trying to define this elusive concept, they tend to assign fictitious properties to it. Often, the claims have nothing to do with what a microservice technically is, but rather with impertinent concepts such as the allegedly "independent" software development style around microservices, or some alleged organization of microservices "around business capabilities". Even when the claims do manage to stick within the technical realm, they range from the unwarranted to the preposterous. I have seen statements to the effect that a microservice is supposed to live in its very own source code repository, that a microservice must be independently deployable, that microservices must communicate with each other via REST, etc. (My favorite one is that they must necessarily be stateless; more on that in another post of mine; see michael.gr - On Stateless Microservices.)
27:00 Placing a network between modules simply to enforce programmer discipline
29:05 There is other levels of isolation I can go to. I can run a docker container per service. That's the coolest stuff right? What that means is I can make it work on my machine so I send my machine to production.
29:52 Now, one thing that's very useful is I don't necessarily want to make this decision up front. And I don't necessarily want to make the same decision in dev as in production. I may want in dev to have a different way that we run things, why? because bringing up 19 docker containers on your laptop is not very much fun. I may prefer to host everything inside a single process to make debugging and such a lot easier when I am running on dev in my laptop. Whereas in production we may go off to multiple nodes.
34:16 If you have maintenance windows, why are you working towards getting rid of your maintenance windows? Is this a business drive or is this you just being like C.V. driven development?My notes:
