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0 pointssb82448y ago0 comments

My first ever docker build was a multi-stage elixir compilation. The end result is a docker image that can be deployed to Heroku or k8s that works great. It's not that hard to get a good docker setup for it. It's even easier if you use Mix and not releases (like I did). However, releases are cool.

Code hot swapping is not really docker friendly (obviously). I haven't done that, but work's general philosophy has been to have recoverable processes such that starting up the app will bring up the correct processes loaded with the right data. However, it's definitely possible to setup hot swapping but is going to be a learning curve to it.

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macintux8y ago· 2 in thread

Code hot swapping is not particularly friendly at all. It's impressive that you can, but the time required to write the code carefully enough and QA the upgrade doesn't seem to be worth it for most applications.

Sure, a telco switch that has to be up 24x7, hot swapping makes a lot of sense. Most applications can spare the brief downtime to reload the old-fashioned way (or have multiple servers to allow upgrades to be done without downtime).

defined8y ago

I'm sorry, I disagree.

Code hot swapping can often trivially be done (by simply compiling and copying the fixed module, then 'l(module)' in the shell) if the module does not change the state record or break function signatures. I have used this countless times to fix a module function with no downtime. You don't always need the full code upgrade procedure, which is indeed far more onerous.

macintux8y ago

I agree, I should have been more specific. Individual module upgrades are indeed straightforward. That didn't sound like what the poster was describing.

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