go-env-manager

README

Go Env Manager

Go Env Manager is a simple, lightweight package to manage environment variables in Go projects. It uses reflection to bind environment variables to struct fields, avoiding the need for code generation. This keeps your codebase clean, while the one-time initialization ensures no noticeable performance cost.

Features

• Load environment variables from .env files.

• Bind structs to environment variables to provide a schema and validation for your env files.

• Supports:

  • Default values
  • Field-specific delimiters
  • Nested structs with prefixes
  • Map binding from multiple env keys
  • Wildcard key matching

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Methods

1. func LoadEnv(fileName string) Loads environment variables from the given .env file.

2. func BindEnv(envStructPtr interface{}) Binds a pointer to a struct to the respective environment variables. The struct tags define the mapping.

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Struct Field Tags

Tag	Description
env	The env variable name linked to the field.
env_def	Default value if the variable is missing.
env_delim	Delimiter for splitting values into slices.
env_prefix	Prefix for all env variables in a nested struct.
env_keys	List of env keys for maps. Supports * wildcard to match keys by prefix.

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Example

type Config struct {
    ProjectName string   `env:"APP_NAME"`
    Difficulty  []string `env_delim:";"`
    Port        int      `env_def:"8080"`
    Email       *struct {
        Host      string
        Port      int
        User      string
        Pass      string
        Signature string
    } `env_prefix:"EMAIL"`
    UserKeys map[string]string `env_keys:"USER*"`
}

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Example .env File

APP_NAME="my-game"
DIFFICULTY="easy;medium;hard"
PORT=4545

EMAIL_HOST=smtp.mailtrap.io
EMAIL_PORT=2525
EMAIL_USER="user@example.com"
EMAIL_PASS="password123"
EMAIL_SIGNATURE="Thanks,
${APP_NAME} Team
Contact: support@gmail.com"

USER1="hello-user-1"
USER2="hello-user-2"
USER3="hello-user-3"

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ENV File Parsing

Go Env Manager supports:

• Quotes: 'single', "double", `backtick`
• Variable substitution inside values (${VAR_NAME})
• Flexible delimiters for lists and maps
• Multi-line values