README.md

envconfig

envconfig is a library which allows you to parse your configuration from environment variables and fill an arbitrary struct.

See the example to understand how to use it, it's pretty simple.

Supported types

• Almost all standard types plus time.Duration are supported by default.
• Slices and arrays
• Arbitrary structs
• Custom types via the Unmarshaler interface.

How does it work

envconfig takes the hierarchy of your configuration struct and the names of the fields to create a environment variable key.

For example:

var conf struct {
    Name string
    Shard struct {
        Host string
        Port int
    }
}

This will check for those 3 keys:

• NAME
• SHARD_HOST
• SHARD_PORT

With slices or arrays, the same naming is applied for the slice. To put multiple elements into the slice or array, you need to separate them with a , (will probably be configurable in the future, or at least have a way to escape)

For example:

var conf struct {
    Ports []int
}

This will check for the key PORTS:

• if your variable is 9000 the slice will contain only 9000
• if your variable is 9000,100 the slice will contain 9000 and 100

For slices of structs, it's a little more complicated. The same splitting of slice elements is done with a , however, each token must follow a specific format like this: {,,...}

For example:

var conf struct {
    Shards []struct {
        Name string
        Port int
    }
}

This will check for the key SHARDS. Example variable content: {foobar,9000},{barbaz,20000}

This will result in two struct defined in the Shards slice.

Future work

• support for defaut values ? don't know how to yet
• support for time.Time values with a layout defined via a field tag
• support for complex types