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Someone asked me today if a function was just a container packaged as a ZIP. Wellll .. not quite. Packaging format isn’t a durable difference, nor it should be. 1/5
First, some terms cos containers is as overloaded as serveless - images define what runs, containers is a running of the image. Crazy how often folks conflate the two. Let’s also leave aside the “aaS” part of FaaS vs orchestration in containers. 2/5
A running function is dynamically bound to its execution environment (resource config, memory/CPU, OS, ideally runtime), as opposed containers which statically binds all of the above. Good use cases for both models, with the trade off being control vs maintenance of the EE. 3/5
A function has a specific programming model:single point of entry/exit, single execution context off which all threads spawn, single request per execution context (in most cases), and stateless (ideally). Containers are less opinionated about the code in them and how it runs. 4/5
ZIPs vs images isn’t where’s it’s at, and I expect that to not matter in the long run - either the tools will speak both, or the services will. ZIPs are ridiculously lightweight today in comparison though, so looking forward to the slimming down of containers as this happens. 5/5
