[LRUG] Config

[Patrick Gleeson]

Hi LRUG,

After the awesome discussion on 'Continuous *' back in January, I wondered
if this might be a place to ask another broad question I've been mulling
for a while now.

According to the 12 factor app (https://12factor.net/config) we should
store our config in environment variables, and in Ruby that means we access
it via ENV. I get the benefit of orthogonal config, but ENV always ends up
feeling pretty unsatisfactory to me for config-heavy apps, for the
following reasons:

(1) No easy way of seeing for any app what config needs to be set
(cmd-shift-F 'ENV' anyone?)
(2) Everything is stringly typed (How many times have I forgotten that
'false' is truthy? And what if a config var is going to be, say, either an
array of integers or null? "&.split(',')&.map(:to_i)" is not my favourite
thing.)
(3) No single place to put sensible defaults if an environment variable not
set
(4) No namespacing or grouping except by prefixes
(5) No protection from typos when reading env vars
(6) Or when writing them
(7) No fine-grained access control to env vars (occasionally useful if
someone semi-technical wants direct control over something set in config
but you don't want them touching the database credentials)
(8) Depending on where you deploy to, your UI for reading and writing env
vars may be better or worse
(9) Depending on where you deploy to, your mechanism for cloning an
environment's vars may be better or worse
(10) No revision history ("Hey Patrick, can we go back to using that
redirect we were using last week?")

For 1 - 5 I normally end up writing a wrapper around ENV with a little DSL
to define the keys the app uses, so that I end up with file with a list of
things like:

namespace :fulfilment_centre do
  set :hours_of_operation, type: :integer, array: true, default: [9,17]
end

And then I can call Config.fulfilment_centre.hours_of_operation with some
confidence

But I don't really know how best to get round 6 - 10. I sort of feel like I
want a Config-as-a-Service platform with web/RESTful interfaces for
defining environments and their config, so that my apps can pull in config
on deploy. Does something like that exist? Or (more likely, I would
imagine) do I want the wrong thing? And if so why?

Any thoughts welcome!

Best,

Patrick
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lrug.org/pipermail/chat-lrug.org/attachments/20190227/8af181c2/attachment.html>