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https://github.com/Jagerente/gocfg

⚙️ Golang config manager. Control your configurations using tags, unmarshal to structs, implement and inject your own value providers and parsers.
https://github.com/Jagerente/gocfg

config configuration configuration-management dotenv env environment-variables go golang

Last synced: 14 days ago
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⚙️ Golang config manager. Control your configurations using tags, unmarshal to structs, implement and inject your own value providers and parsers.

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## GoCfg

## Key Features

- Unmarshal from **Environment Variables**, **.env** and any other sources right to your structs.
- Set default values for each field using tags.
- Easy to inject as much custom parsers as you need.
- Easy to inject your own values providers as much as you need and use them all at once with priority.
- Automatic documentation generator.

## Quick start

### Install package:

```bash
go get -u github.com/Jagerente/gocfg
```

### Basic usage:

It will use environment variables and default values defined in tags.

```go
package main

import (
"github.com/Jagerente/gocfg"
"github.com/Jagerente/gocfg/pkg/parsers"
"github.com/Jagerente/gocfg/pkg/values"
"time"
)

type LoggerConfig struct {
LogLevel string `env:"LOG_LEVEL" default:"debug"`
}

type RedisConfig struct {
RedisHost string `env:"REDIS_HOST" default:"localhost"`
RedisPort uint16 `env:"REDIS_PORT" default:"6379"`
RedisUser string `env:"REDIS_USER,omitempty"`
RedisPassword string `env:"REDIS_PASS"`
RedisDatabase string `env:"REDIS_DATABASE"`
}

type AppConfig struct {
// Supported Tags:
// - env: Specifies the environment variable name.
// - default: Specifies the default value for the field.
// - omitempty: Allows empty fields.
// If both the parsed value and the default value are empty,
// the field will be set to the zero value for its type in Go.

LogLevel LoggerConfig
RedisConfig RedisConfig
BoolField bool `env:"BOOL_FIELD"`
StringField string `env:"STRING_FIELD"`
IntField int `env:"INT_FIELD"`
Int8Field int8 `env:"INT8_FIELD"`
Int16Field int16 `env:"INT16_FIELD"`
Int32Field int32 `env:"INT32_FIELD"`
Int64Field int64 `env:"INT64_FIELD"`
UintField uint `env:"UINT_FIELD"`
Uint8Field uint8 `env:"UINT8_FIELD"`
Uint16Field uint16 `env:"UINT16_FIELD"`
Uint32Field uint32 `env:"UINT32_FIELD"`
Uint64Field uint64 `env:"UINT64_FIELD"`
Float32Field float32 `env:"FLOAT32_FIELD"`
Float64Field float64 `env:"FLOAT64_FIELD"`
TimeDurationField time.Duration `env:"TIME_DURATION_FIELD"`
ByteSliceField []byte `env:"BYTE_SLICE_FIELD"`
StringSliceField []string `env:"STRING_SLICE_FIELD" default:"string1,string2,string3"`
EmptyField string `env:"EMPTY_FIELD,omitempty"`
WithDefaultField string `env:"WITH_DEFAULT_FIELD" default:"ave"`
}

func main() {
cfg := gocfg.NewDefault()

// Equals to
cfg = gocfg.NewEmpty().
UseDefaults().
AddParserProviders(parsers.NewDefaultParserProvider()).
AddValueProviders(values.NewEnvProvider())

appConfig := new(AppConfig)
if err := cfg.Unmarshal(appConfig); err != nil {
panic(err)
}
}

```

### Default Type Parsers

> The following types are supported by default parsers:

- time.Duration
- bool
- string
- int, int8, int16, int32, int64
- uint, uint8, uint16, uint32, uint64
- float32, float64
- slices: bytes, strings

### .env file

```go
package main

import (
"github.com/Jagerente/gocfg"
"github.com/Jagerente/gocfg/pkg/parsers"
"github.com/Jagerente/gocfg/pkg/values"
)

type AppConfig struct {
BoolField bool `env:"BOOL_FIELD"`
StringField string `env:"STRING_FIELD"`
IntField int `env:"INT_FIELD"`
}

func main() {
// With default '.env' file
dotEnvProvider, _ := values.NewDotEnvProvider()

// With custom env file path
dotEnvProvider, _ = values.NewDotEnvProvider("local.env")

// With multiple env files
dotEnvProvider, _ = values.NewDotEnvProvider("local.env", "dev.env")

cfg := gocfg.NewDefault().
AddValueProviders(dotEnvProvider)

// Equals to
cfg = gocfg.NewEmpty().
UseDefaults().
AddParserProviders(parsers.NewDefaultParserProvider()).
AddValueProviders(
values.NewEnvProvider(),
dotEnvProvider,
)

appConfig := new(AppConfig)
if err := cfg.Unmarshal(appConfig); err != nil {
panic(err)
}
}
```

### Custom key tag

```go
package main

import (
"github.com/Jagerente/gocfg"
)

type AppConfig struct {
BoolField bool `mapstructure:"BOOL_FIELD"`
StringField string `mapstructure:"STRING_FIELD"`
IntField int `mapstructure:"INT_FIELD"`
}

func main() {
cfg := gocfg.NewDefault().
UseCustomKeyTag("mapstructure")

appConfig := new(AppConfig)
if err := cfg.Unmarshal(appConfig); err != nil {
panic(err)
}
}

```

### Custom parser provider

```go
package main

import (
"github.com/Jagerente/gocfg"
"reflect"
"time"
)

type CustomParserProvider struct {
}

func NewCustomParserProvider() *CustomParserProvider {
return &CustomParserProvider{}
}

func (p *CustomParserProvider) Get(field reflect.Value) (func(v string) (any, error), bool) {
switch field.Type() {
case reflect.TypeOf(time.Duration(83)):
return func(v string) (any, error) {
return time.ParseDuration(v)
}, true
default:
return nil, false
}
}

type AppConfig struct {
BoolField bool `env:"BOOL_FIELD"`
StringField string `env:"STRING_FIELD"`
IntField int `env:"INT_FIELD"`
}

func main() {
customParserProvider := NewCustomParserProvider()

cfg := gocfg.NewDefault().
AddParserProviders(customParserProvider)

appConfig := new(AppConfig)
if err := cfg.Unmarshal(appConfig); err != nil {
panic(err)
}
}

```

### Custom value provider

```go
package main

import (
"github.com/Jagerente/gocfg"
"os"
)

type CustomValueProvider struct {
}

func NewCustomValueProvider() *CustomValueProvider {
return &CustomValueProvider{}
}

func (p *CustomValueProvider) Get(key string) string {
return os.Getenv("CUSTOM_" + key)
}

type AppConfig struct {
BoolField bool `env:"BOOL_FIELD"`
StringField string `env:"STRING_FIELD"`
IntField int `env:"INT_FIELD"`
}

func main() {
customValueProvider := NewCustomValueProvider()

cfg := gocfg.NewDefault().
AddValueProviders(customValueProvider)

appConfig := new(AppConfig)
if err := cfg.Unmarshal(appConfig); err != nil {
panic(err)
}
}

```

### Documentation generation

1. Let's say you have such config file `/internal/config/config.go`:

```go
package config

import (
"github.com/Jagerente/gocfg"
"github.com/Jagerente/gocfg/pkg/values"
"time"
cache_factory "your_cool_app/internal/router/cache"
)

type LoggerConfig struct {
LogLevel int `env:"LOG_LEVEL" default:"6" description:"https://pkg.go.dev/github.com/sirupsen/[email protected]#Level"`
ReportCaller bool `env:"REPORT_CALLER" default:"true"`
LogFormatter int `env:"LOG_FORMATTER" default:"0"`
}

type CassandraConfig struct {
CassandraHosts string `env:"CASSANDRA_HOSTS" default:"127.0.0.1"`
CassandraKeyspace string `env:"CASSANDRA_KEYSPACE" default:"user_data_service"`
}

type RouterConfig struct {
ServerPort uint16 `env:"SERVER_PORT" default:"8080"`
Debug bool `env:"ROUTER_DEBUG" default:"true"`
CacheAdapter string `env:"CACHE_ADAPTER,omitempty" description:"Leave blank to not use.\nPossible values:\n- redis\n- memcache"`
CacheAdapterTTL time.Duration `env:"CACHE_ADAPTER_TTL,omitempty" default:"1m"`
CacheAdapterNoCacheParam string `env:"CACHE_ADAPTER_NOCACHE_PARAM,omitempty" default:"no-cache"`
}

type RedisCacheAdapterConfig struct {
RedisAddr string `env:"CACHE_ADAPTER_REDIS_ADDR,omitempty" default:":6379"`
RedisDB int `env:"CACHE_ADAPTER_REDIS_DB,omitempty" default:"0"`
RedisUsername string `env:"CACHE_ADAPTER_REDIS_USERNAME,omitempty"`
RedisPassword string `env:"CACHE_ADAPTER_REDIS_PASSWORD,omitempty"`
}

type MemcacheCacheAdapterConfig struct {
Capacity int `env:"CACHE_ADAPTER_MEMCACHE_CAPACITY,omitempty" default:"10000000"`
CachingAlgorithm cache_factory.Algorithm `env:"CACHE_ADAPTER_MEMCACHE_CACHING_ALGORITHM,omitempty" default:"LRU"`
}
type Config struct {
LoggerConfig `title:"Logger configuration"`
RouterConfig `title:"Router configuration"`
RedisCacheAdapterConfig `title:"Redis Cache Adapter configuration"`
MemcacheCacheAdapterConfig `title:"Memcache Cache Adapter configuration"`
CassandraConfig `title:"Cassandra configuration"`
}

func New() (*Config, error) {
var cfg = new(Config)

cfgManager := gocfg.NewDefault()
if dotEnvProvider, err := values.NewDotEnvProvider(); err == nil {
cfgManager = cfgManager.AddValueProviders(dotEnvProvider)
}

if err := cfgManager.Unmarshal(cfg); err != nil {
return nil, err
}

return cfg, nil
}

```

2. Create new app, for example `/cmd/docs/main.go`:

```go
package main

import (
"fmt"
"github.com/Jagerente/gocfg"
"github.com/Jagerente/gocfg/pkg/docgens"
"os"
"your_cool_app/internal/config"
)

const outputFile = ".env.dist.generated"

func main() {
cfg := new(config.Config)

file, err := os.Create(outputFile)
if err != nil {
panic(fmt.Errorf("error creating %s file: %v", outputFile, err))
}

cfgManager := gocfg.NewDefault()
if err := cfgManager.GenerateDocumentation(cfg, docgens.NewEnvDocGenerator(file)); err != nil {
panic(err)
}
}

```

3. Run it by executing `go run cmd/docs/main.go`; it will generate the following file `.env.dist.generated`:

```go
# Auto-generated config

#############################
# Logger configuration
#############################

# Description:
# https://pkg.go.dev/github.com/sirupsen/[email protected]#Level
LOG_LEVEL=6

REPORT_CALLER=true

LOG_FORMATTER=0

#############################
# Router configuration
#############################

SERVER_PORT=8080

ROUTER_DEBUG=true

# Allowed to be empty
# Description:
# Leave blank to not use.
# Possible values:
# - redis
# - memcache
CACHE_ADAPTER=

# Allowed to be empty
CACHE_ADAPTER_TTL=1m

# Allowed to be empty
CACHE_ADAPTER_NOCACHE_PARAM=no-cache

#############################
# Redis Cache Adapter configuration
#############################

# Allowed to be empty
CACHE_ADAPTER_REDIS_ADDR=:6379

# Allowed to be empty
CACHE_ADAPTER_REDIS_DB=0

# Allowed to be empty
CACHE_ADAPTER_REDIS_USERNAME=

# Allowed to be empty
CACHE_ADAPTER_REDIS_PASSWORD=

#############################
# Memcache Cache Adapter configuration
#############################

# Allowed to be empty
CACHE_ADAPTER_MEMCACHE_CAPACITY=10000000

# Allowed to be empty
CACHE_ADAPTER_MEMCACHE_CACHING_ALGORITHM=LRU

#############################
# Cassandra configuration
#############################

CASSANDRA_HOSTS=127.0.0.1

CASSANDRA_KEYSPACE=user_data_service

```