feat: env vars as vectors

[kdmoreira]

This PR enables configurations coming from environment variables that represent multiple values to be stored as a vector in config.edn, which is not supported by aero config as of now. An example of such variable:
ALLOWED_ORIGINS="https://domain.a.com, https://domain.b.com"

It's expected that env variables are comma-separated strings.
Their configs should have a #csv tag literal.
Trailing commas and whitespaces are handled.

[rafaeldelboni]

Nice catch, that's definitely something I didn't thought when doing this hahaha
Thanks for your contribution!

I think since the config component is using aero under the hood, we can simplify your code a little bit using tag literals.

I did a small POC to check the idea to help you:

(ns codes.clj.docs.backend.config
  (:require [aero.core :as aero]
            [clojure.string :as string]))

(defn- str-var->vector-var
  "Converts a string config variable to a vector of strings, when applicable.
  Environment variables are expected to be set as comma-separated values."
  [value]
  (if (string? value)
    (let [split-configs (-> value
                            (string/split  #","))
          env-config (->> split-configs
                          (map string/trim)
                          (remove empty?))]
      env-config)
    value))

(defmethod aero/reader 'csv
  [opts tag value]
  (prn opts tag value)
  (str-var->vector-var value))

(aero/read-config "config.edn")

Where the config.edn is something like this:

{:debug #boolean #or [#env DEBUG "true"]
 :webserver {:port #long #or [#env PORT 8080]
             :factor #double #or [#env FACTOR "1.2"]
             :mode #keyword #or [#env MODE "my-mode"]
             :origins #csv #or [#env ORIGINS "my, domain"]}}

With this we don't need to wrap the config component in a function just remember to require the codes.clj.docs.backend.config before starting the component.

We can do this PR here, evaluate and later we can move this to the config component in parenthesin/components

WDYT?

[kdmoreira]

Good suggestion, @rafaeldelboni, I agree this makes things simpler.
I've applied it and changed the tests to reflect the new approach.
Having this in parenthesin's components eventually would be nice, indeed.
Thanks for the improvement.

[rafaeldelboni]

🔝 Thanks!