Charmil Config Management Package

The Charmil Config package offers a convenient mechanism for both host and plugin developers to manage configurations in their command-line interface (CLI) applications made using Cobra.

Features:#

Helps in maintaining all available configurations in a single, centralized local config file.
Provides the plugin developers with a functionality to add their CLI configurations to the host CLI local config file with ease.
Provides the host CLI developers with a set of methods to read/write configurations from/to a local config file.

Steps to Use:#

For host CLI developers:#
1. Open the file where the root command of your CLI is defined using Cobra.
2. Import the Charmil Config package by adding the following line at the top of that file:
```
import c "github.com/aerogear/charmil/core/config"
```
3. Define a struct whose fields represent the keys to all the values that you want to store as config and create an instance of it.
  Important: Every field of the defined struct needs to be exportable (ie. start with an uppercase letter). The unexportable fields cannot be stored as config.
  Example:
```
type config struct {  Key1 string  Key2 string  Key3 string  Key4 string}
cfg = &config{}
```
4. Store a new instance of the Charmil Config handler by calling the NewHandler function while passing the path of local config file and the instance of the config struct (initialized in the last step) as arguments.
  Example:
```
h = c.NewHandler("./examples/host/config.json", cfg)
```
5. Load config values from the local config file using the Load method.
  Example:
```
err := h.Load()if err != nil {    log.Fatal(err)}
```
6. You can set/get/modify values under any key of config using the idiomatic way to interact with structs in Golang.
  Example:
```
// Sets a value into configcfg.Key4 = "val4"
// Overwrites a value in configcfg.Key2 = "newVal2"
// Returns the value under specified key in configfmt.Println(cfg.Key3) // Prints: val3
```
7. Write current config into the local config file using the Save method.
  Example:
```
err = h.Save()if err != nil {  log.Fatal(err)}
```
For plugin developers:#
1. Open the file where the root command of your CLI is defined using Cobra.
2. Import the Charmil Config package by adding the following line at the top of that file:
```
import c "github.com/aerogear/charmil/core/config"
```
3. Define a struct whose fields represent the keys to all the values that you want to store as config and create an instance of it. Important: Every field of the defined struct needs to be exportable (ie. start with an uppercase letter). The unexportable fields cannot be stored as config.
  Example:
```
type config struct {  Key5 string  Key6 string  Key7 string  Key8 string}
cfg = &config{}
```
4. You can set/get/modify values under any key of config using the idiomatic way to interact with structs in Golang.
  Example:
```
// Sets values into configcfg.Key5 = "val5"cfg.Key6 = "val6"cfg.Key7 = "oldVal7"cfg.Key8 = "val8"
// Overwrites a value in configcfg.Key7 = "val7"
// Returns the value under specified key in configfmt.Println(cfg.Key6) // Prints: val6
```
5. Use the MergePluginCfg function to merge the current plugin config into the host CLI config struct.
  Example:
```
err = c.MergePluginCfg(pluginName, h, cfg)if err != nil {    log.Fatal(err)}
```
  where pluginName is the name of the plugin (as you want it in the local config file), h is the config handler passed from the host CLI and cfg is a pointer to an instance of the current config file (initialized in step 3).

Here's an example for the same:#

Initial Configurations [Before running the Host CLI]:#
- config.json file:
```
{  "key1": "val1",  "key2": "val2",  "key3": "val3"}
```
- Plugin A's Config Struct:
```
{val4 val5 val6}
```
- Plugin B's Config Struct:
```
{val7 val8 val9}
```

Final Configurations [After running the Host CLI]:#

config.json file:

{  "key1": "val1",  "key2": "val2",  "key3": "val3",  "plugins": {    "pluginA": {      "Key4": "val4",      "Key5": "val5",      "Key6": "val6"    },    "pluginB": {      "Key7": "val7",      "Key8": "val8",      "Key9": "val9"    }  }}

Features:#

Steps to Use:#

For host CLI developers:#

For plugin developers:#

Here's an example for the same:#

Initial Configurations [Before running the Host CLI]:#

Final Configurations [After running the Host CLI]:#