🌀 YACL - Yet Another Config Loader
YACL is a package designed to simplify configuration management in Go applications. It allows you to load and merge configuration from various sources such as environment variables, command-line flags, and multiple file formats into an arbitrary config structure instance. Also, it is designed to work out of the box with just a single line of code to load your configuration.
🌟 Features
- Multiple sources to load config hierarchically:
- 🚩 Command-line flags
- 🌐 Environment variables
- 📜 YAML files
- 📄 JSON files
- 💾 Binary files
- 🆕 Default config instance (optional)
- Automatically merges configs' fields with non-default values from different sources
- Supports nested structs
- Supports slices
- No need to bind variables to config struct by hand
- Easy-to-use single line convenient API
- Aliases with the tag
yacl: "newFieldName"
📝 Supported types
- string
- bool
- uint32, uin64
- int32, int64
- float64
- []string
- []bool
- []uint32, []uint64
- []int32, []int64
- []float64
💻 Installation
go get github.com/andrew528i/yacl
🧑💻 Usage
Here's an example of how to use YACL to load configuration from multiple sources with just a single line of code.
import (
"fmt"
"github.com/andrew528i/yacl"
)
type DatabaseConfig struct {
Hostname string
Port uint
}
type Config struct {
Database DatabaseConfig
CanRestart bool
Tags []string
Temperatures []float64
}
func DefaultConfig() *Config {
// Optional fallback struct with default values
return &Config{
Database: DatabaseConfig{Hostname: "localhost-default"},
CanRestart: true,
Tags: []string{"hello", "world"},
Temperatures: nil,
}
}
func main() {
cfg, err := yacl.Parse[Config](DefaultConfig()) // DefaultConfig() is optional
// cfg, err := yacl.Parse[Config]()
if err != nil {
panic(err)
}
fmt.Printf("%+v\n", cfg)
}
YAML file
config.yaml content:
database:
hostname: localhost-yaml
port: 5432
can_restart: true
tags:
- hello
- world
temperatures:
- 12.75
- 17.49929
- 27.46
$ ./app
&{Database:{Hostname:localhost-yaml Port:5432} CanRestart:true Tags:[hello world] Temperatures:[12.75 17.49929 27.46]}
Environment variables
$ export DATABASE_HOSTNAME=localhost-env
$ export DATABASE_PORT=1234
$ export CAN_RESTART=true
$ export TAGS=one,two
$ export TEMPERATURES=123.321,234.432,456.654
$ ./app
&{Database:{Hostname:localhost-env Port:1234} CanRestart:true Tags:[one two] Temperatures:[123.321 234.432 456.654]}
Command-line flags
$ ./app -database-hostname localhost-flags -database-port 6543 -can-restart -tags aaa -tags bbb -tags ccc -temperatures 1.223 -temperatures 2.332
&{Database:{Hostname:localhost-flags Port:6543} CanRestart:true Tags:[aaa bbb ccc] Temperatures:[1.223 2.332]}
Documentation
Global params
SetEnvPrefix
Use this to set a global prefix for environment variables:
yacl.SetEnvPrefix("APP")
For example, struct field HTTPPort uint
will become APP_HTTP_PORT
.
SetEnvDelimiter
yacl.SetEnvDelimiter("__")
For example, struct field HTTPPort uint
will become HTTP__PORT
.
SetFilePath
Specifies the path where to look for config files for all the formats: yaml, json, and bin. Also, YACL always looks for config files in the current working directory.
SetFilename
Sets the default filename for the config filename. For example:
yacl.SetFilename("my-config")
So YACL will look for those files: my-config.yaml, my-config.json, and my-config.bin.
SetFlagDelimiter
yacl.SetFlagDelimiter("_")
So, struct field DatabasePort uint
will become command-line flag -database_port
.
Parse
Parses all the config source hierarchically. See the usage section for more details and examples.
🌟 Instance parameters
In order to create a separate instance of YACL with its own params you can:
y := yacl.New()
SetEnvPrefix
Same as the global version.
SetEnvDelimiter
Same as the global version.
AddFilePath
Adds a path to look for a config.
SetFilename
Same as the global version.
SetFlagDelimiter
Same as the global version.
SetIgnoreFlags
In some cases, you may need not to touch flag params. For such a case, you can yacl.SetIgnoreFlags(true)
and YACL will not clear default flags.
Parse
Same as the global version.