Supported types

Category	Types
Strings	string
Booleans	bool (strconv.ParseBool: 1, t, true, TRUE, …)
Integers	int, int8…int64, uint, uint8…uint64
Floats	float32, float64
Time	time.Duration ("5s", "1h30m"), time.Time (RFC3339 or layout tag)
Collections	[]T (any supported T), map[string]T (key:value pairs)
Pointers	*T for any supported T (allocated only when a value is present)
Nested	structs (recursed into, with optional envPrefix)
Custom	any encoding.TextUnmarshaler, or any type via WithTypeParser

Slices and maps use the field’s separator (default ,); map entries are key:value. For example LABELS=a:1,b:2 decodes into map[string]int{"a":1,"b":2}.

Slices of structs

A []Struct field is decoded from indexed keys: the field’s env name, then _<index>_, then the element’s key. Decoding starts at index 0 and stops at the first index with no keys present.

type Server struct {
    Host string `env:"HOST"`
    Port int    `env:"PORT"`
}
type Config struct {
    Servers []Server `env:"SERVER"`
}

SERVER_0_HOST=a
SERVER_0_PORT=1
SERVER_1_HOST=b
SERVER_1_PORT=2