cfginterpolator

cfginterpolator is an interpolate library in golang allowing to include data from external sources in your configuration

cfginterpolator ingest a map[string]interface{} with as many nested map[string]interface{} as you want.

This data structure can, as example, be produced by:

• a yaml file read by gopkg.in/yaml.v3

• a json file read by encoding/json

After cfginterpolator Interpolate job, you can use https://github.com/mitchellh/mapstructure to inject the map[string]interface{} interpolated by cfginterpolator to any kind of struct you defined.

Example

package main

import (
    "github.com/mitchellh/mapstructure"
    "github.com/bbayszczak/cfginterpolator"
)

type Config struct {
    Username string
    Password string
}

var rawConfig = `
---
username: "John-David"
password: "{{env::PASSWORD}}"
`

func main() {
    var config map[string]interface{}
    var configStruct Config
    if err := yaml.Unmarshal([]byte(rawConfig), &config); err != nil {
		panic("cannot unmarshall data: %v", err)
	}
    cfginterpolator.Interpolate(config)
    mapstructure.Decode(config, &configStruct)
}

Available external datasources

environment variables

{{env::ENV_VAR1}} will be replaced by the value of the environment variable ENV_VAR1

External datasources to be implemented

• environment variables

• file

• Hashicorp Vault

• Hashicorp Consul

Improvements

• allow to interpolate several times in the same value

• not panic when interpolator name does not exists

• add error returns