Application Configuration UX

[alexanderbez]

Having worked with a few projects at optimum already and seeing how gateway has progressed and it's use of the common repo's config package, I really believe we can keep configuration flow and code significantly simpler. For starters, I think there are some annoyances around DevX:

• Defaults can be specified via field tags and directly in types. This means you now have 2x the surface area to keep things in check.
• common/config code has reflect code, is unwieldy and complex to follow; granted its not code that ever really needs to change, but the point remains.
• ENV vars needs to be explicitly defined in field tags, whereas they can be implicitly derived from a single yaml field.

What I think we get right:

• Precedence: env var > flag > config file
• YAML (although I like TOML too)

Proposal

• KISS. Just keep it simple. Define a Config struct with the appropriate yaml tags.
• Use validate tag annotations for basic validation.
• Use koanf to load and parse everything (no need to maintain parsing ourselves -- it has all the parsers we need).
• Config file should be kept by default in $HOME/.config/<app-name>/config.yaml (as with most CLI tools you'll use today).

A simple and clean example can be seen here: https://github.com/getoptimum/flexnode/blob/main/pkg/config/config.go#L258-L313

• Load from file
• Read ENV var (override)
• Unmarshal with defaults

[linear-code]

OPT-775

[alexanderbez]

Was this closed by a PR or decoded not to do it? If the latter, when issues are closed, which is fine, provide some context on the closure 🙏 .

[swarna1101]

apologies the issue clousre was a mistake. I reopened it.