Using spf13/viper to gather parameters from various sources can be tricky. You will probably run into the problem of having to redefine default parameters for each means of input. This example shows how to to load parameters from different sources without having to define them multiple times. The common priority for input methods is this:

1. CLI parameters
2. Environment variables
3. Config file
4. Default values

Checkout the cli package on how to setup this config.

Build the application

make build

Parameters can be passed into the application in these 4 ways:

config.yaml:

param1: "param from config"

defaultConfig in config.go:

var defaultConfig = config{
    Param2: "param with default value",
}

Environment variable

PARAM1="param from env" ./our_app

Cli parameter

./our_app --param1="param from cli"