env

README

Env Source

The env source reads config from environment variables

Format

We expect environment variables to be in the standard format of FOO=bar

Keys are converted to lowercase and split on underscore.

Example

DATABASE_ADDRESS=127.0.0.1
DATABASE_PORT=3306

Becomes

{
    "database": {
        "address": "127.0.0.1",
        "port": 3306
    }
}

Prefixes

Environment variables can be namespaced so we only have access to a subset. Two options are available:

WithPrefix(p ...string)
WithStrippedPrefix(p ...string)

The former will preserve the prefix and make it a top level key in the config. The latter eliminates the prefix, reducing the nesting by one.

Example:

Given ENVs of:

APP_DATABASE_ADDRESS=127.0.0.1
APP_DATABASE_PORT=3306
VAULT_ADDR=vault:1337

and a source initialized as follows:

src := env.NewSource(
    env.WithPrefix("VAULT"),
    env.WithStrippedPrefix("APP"),
)

The resulting config will be:

{
    "database": {
        "address": "127.0.0.1",
        "port": 3306
    },
    "vault": {
        "addr": "vault:1337"
    }
}

New Source

Specify source with data

src := env.NewSource(
	// optionally specify prefix
	env.WithPrefix("MICRO"),
)

Load Source

Load the source into config

// Create new config
conf := config.NewConfig()

// Load env source
conf.Load(src)

Documentation

Index

• Variables
• func NewSource(opts ...source.Option) source.Source
• func WithPrefix(p ...string) source.Option
• func WithStrippedPrefix(p ...string) source.Option

Variables

var (
	DefaultPrefixes = []string{}
)

Functions

func NewSource

func NewSource(opts ...source.Option) source.Source

NewSource returns a config source for parsing ENV variables. Underscores are delimiters for nesting, and all keys are lowercased.

Example:

"DATABASE_SERVER_HOST=localhost" will convert to

{
    "database": {
        "server": {
            "host": "localhost"
        }
    }
}

func WithPrefix

func WithPrefix(p ...string) source.Option

WithPrefix sets the environment variable prefixes to scope to. These prefixes will not be removed. Each prefix will be considered a top level config entry.

func WithStrippedPrefix

func WithStrippedPrefix(p ...string) source.Option

WithStrippedPrefix sets the environment variable prefixes to scope to. These prefixes will be removed from the actual config entries.