simple_config

simple_config

An example configuration package

This package is a setup for brain-dead config parsing. Sure, it's verbose for two real parameters and there are is a lot of boilerplate for what it does, but nothing is going to go wrong and it is fully extendable to a real world project without needing any complicated additional libraries involved. Don't get me wrong, Cobra and Viper are super powerful and well maintained, but 98% of the time I only really want one command per executable and every time I touch Cobra or Viper I spend at least half an hour reading through documentation. Why bother for the vast majority of my public work just involves stupid things like a slack-bot to render text as party parrots?

Note that while this looks like a lot of code for what it does, it does have a good set of functionality for a small project:

• Clear precedence of config sources
• Only basic flag library used
• Flag for debug output
• Flag to choose config file (including option to skip file loading without needing a separate flag!)
• Annotations for env var mapping and file loading of the config are defined by the loader struct itself
• Default values kept directly above config loader structs for easy comparison
• No super ugly long parameter sets to pass from flag parsing to initialize structs (builder pattern preferred)
• Reloadable, so if you create an init ConfigLoader from flags you can then do hot reloads in response to e.g. a SIGHUP (see examples/simple_config/main.go)
• No magic hidden in a library you need to look up

If you want to try it, it was written so that the precedence is flags > file > env. The default values in the code are { Host: "localhost", Port: 1443 }.

Try running it a few different ways and seeing what happens!

go run .
PORT=3000 go run .
PORT=3000 go run . --port 5000
PORT=3000 go run . --port 5000 --host "example.com"
PORT=3000 HOST=host.from.env go run .
PORT=3000 HOST=host.from.env go run . --config alt.toml
HOST=host.from.env go run . --config none
PORT=3000 HOST=host.from.env go run . --config .alt.toml --port 5000 --host host.from.flag
PORT=3000 HOST=host.from.env go run . --config .alt.toml --port 5000 --host host.from.flag
PORT=3000 HOST=host.from.env go run . --log debug --config alt.toml --port 5000 --host host.from.flag