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https://github.com/JeremyLoy/config
12 factor configuration as a typesafe struct in as little as two function calls
https://github.com/JeremyLoy/config
12-factor cloud configuration environment go golang minimal
Last synced: about 2 months ago
JSON representation
12 factor configuration as a typesafe struct in as little as two function calls
- Host: GitHub
- URL: https://github.com/JeremyLoy/config
- Owner: JeremyLoy
- License: mit
- Created: 2019-04-02T13:41:22.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2022-05-30T19:57:34.000Z (over 2 years ago)
- Last Synced: 2024-07-31T20:43:59.192Z (4 months ago)
- Topics: 12-factor, cloud, configuration, environment, go, golang, minimal
- Language: Go
- Homepage:
- Size: 96.7 KB
- Stars: 336
- Watchers: 6
- Forks: 15
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
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README
# Config
[](https://pkg.go.dev/github.com/JeremyLoy/config)
[](https://github.com/avelino/awesome-go)
[](https://github.com/JeremyLoy/config/actions/workflows/ci.yml)
[](https://goreportcard.com/report/github.com/JeremyLoy/config)
[](https://coveralls.io/github/JeremyLoy/config?branch=master)
[](https://github.com/JeremyLoy/config/issues)
[](https://github.com/JeremyLoy/config/LICENSE)
[](https://github.com/JeremyLoy/config/releases)
Manage your application config as a typesafe struct in as little as two function calls.
```go
type MyConfig struct {
DatabaseUrl string `config:"DATABASE_URL"`
FeatureFlag bool `config:"FEATURE_FLAG"`
Port int // tags are optional. PORT is assumed
...
}
var c MyConfig
err := config.FromEnv().To(&c)
```
## How It Works
It's just simple, pure stdlib.
* A field's type determines what [strconv](https://pkg.go.dev/strconv) function is called.
* All string conversion rules are as defined in the [strconv](https://pkg.go.dev/strconv) package
* `time.Duration` follows the same parsing rules as [time.ParseDuration](https://pkg.go.dev/time#ParseDuration)
* `*net.URL` follows the same parsing rules as [url.Parse](https://pkg.go.dev/net/url#URL.Parse)
* NOTE: `*net.URL` fields on the struct **must** be a pointer
* If chaining multiple data sources, data sets are merged.
Later values override previous values.
```go
config.From("dev.config").FromEnv().To(&c)
```
* Unset values remain intact or as their native [zero value](https://tour.golang.org/basics/12)
* 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.
* Any errors encountered are aggregated into a single error value
* the entirety of the struct is always attempted
* failed conversions (i.e. converting "x" to an int) and file i/o are the only sources of errors
* missing values are not errors
## Why you should use this
* It's the cloud-native way to manage config. See [12 Factor Apps](https://12factor.net/config)
* 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.
* One exception is `*url.URL`, which is explicitly a pointer for ease of use, matching the `url` package conventions