Support $XDG_CONFIG_HOME for config file location

[gtback]

Overview

ecctl should be able to read a config file located at $XDG_CONFIG_HOME/ecctl/config.{json,yaml,toml,hcl} (by convention, $HOME/.config/ecctl/config.{json,yaml,toml,hcl}) in line with the XDG Base Directory Specification.

Possible Implementation

Caveat: I'm not a Golang developer.
It seem like Viper supports this, but not implicitly.

Adding viper.AddConfigPath("$XDG_CONFIG_HOME/ecctl") to func setupViper should do the trick:

diff --git a/cmd/root.go b/cmd/root.go
index 1a50581..d5cc47c 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -137,6 +137,7 @@ func setupViper(v *viper.Viper) {
        v.SetEnvKeyReplacer(strings.NewReplacer("-", "_"))
        v.AutomaticEnv()
        v.AddConfigPath(ecctlHomePath)         // adding home directory as first search path
+       v.AddConfigPath("$XDG_CONFIG_HOME/ecctl")
        v.SetConfigName(v.GetString("config")) // name of config file (without extension)

        // If a config file is found, read it in.

A more thorough implementation might be to split up ecctlHomePath to different variables that could also be used in case the tool needs to store user data or cache data ($XDG_DATA_HOME and $XDG_CACHE_HOME, respectively), rather than making the assumption they'll all be in the same ~/.ecctl directory.

Testing

• Test that if $XDG_CONFIG_HOME is defined, ecctl init writes the config file in that directory.
• Test that if $XDG_CONFIG_HOME is defined and $XDG_CONFIG_HOME/ecctl/config.json exists, it is used for configuration values.
• Test that if both $XDG_CONFIG_HOME/ecctl/config.json and $HOME/.ecctl/config.json exist, the latter takes priority (I think? It depends on the implementation and which is given higher precedence)
• Test that if $XDG_CONFIG_HOME is defined and $XDG_CONFIG_HOME/ecctl/config.json doesn't exist, it falls back to $HOME/.ecctl/config.json if it exists, otherwise the missing ecctl config file message is diplayed.

Context

I try to keep my $HOME directory free of extraneous dotfiles/directories.

Your Environment

macOS (but any Linux/Unix variant will be similarly affected).