config's Introduction

Config

Manage your application config as a typesafe struct in as little as two function calls.

type MyConfig struct {
	DatabaseUrl string `config:"DATABASE_URL"`
	FeatureFlag bool   `config:"FEATURE_FLAG"`
	Port        int // tags are optional. PORT is assumed
	...
}

var c MyConfig
config.FromEnv().To(&c)

How It Works

Its just simple, pure stdlib.

A field's type determines what strconv function is called.
All string conversion rules are as defined in the strconv package
If chaining multiple data sources, data sets are merged. Later values override previous values.
```
config.From("dev.config").FromEnv().To(&c)
```
Unset values remain as their native zero value
Nested structs/subconfigs are delimited with double underscore
- e.g. PARENT__CHILD
Env vars map to struct fields case insensitively
- NOTE: Also true when using struct tags.

Why you should use this

Its the cloud-native way to manage config. See 12 Factor Apps
Simple:
- only 2 lines to configure.
Composeable:
- Merge local files and environment variables for effortless local development.
small:
- only stdlib
- < 180 LoC

Design Philosophy

Opinionated and narrow in scope. This library is only meant to do config binding. Feel free to use it on its own, or alongside other libraries.

Only structs at the entry point. This keeps the API surface small.
Slices are space delimited. This matches how environment variables and commandline args are handled by the go cmd.
No slices of structs. The extra complexity isn't warranted for such a niche usecase.
No maps. The only feature of maps not handled by structs for this usecase is dynamic keys.
No pointer members. If you really need one, just take the address of parts of your struct.

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