env package

Designed to provide simple and useful tooling to popoulate simple structs and provide managagement and helpful services utilizing struct tags instead of package like flag or third-party solutions.

type params struct {
	Action    string `env:"A,require,order" help:"a name to use"`
	Secret    string `env:"hidden" help:"a secret"`
	Flag      bool   `default:"on"  help:"a flag setting"`
	Number    int    `default:"5" help:"a number"`
	timestamp int64  // not parsed or reported in Summary
}

func main() {
	var param params
	paths := env.NewEnv(&param)
}

Set struct params and populate by calling env.NewEnv(&param) to parse and populate the struct as shown.

• Any default value is overloaded by system environment that is in turn overloaded by any command line values.

Supported types in env.Parser are limited to string, bool, and int.

• Bool understands and accepts: on, yes, ok, true, and 1 and their associated negative counter parts.
• Everything you want can be derived from these three basic types, including arrays and maps that utilize your own encoding and decoding.
  • Array can be passed or set as one,two,three and split by on comman, simarly a map can be encode as k1:v1,k1:v2 and decoded by splitting on comma and then each set split on the colon.

---

Struct tag element supported and descriptions.

• env: alias,order,require,environ,hidden

  • alias support can be short form of the switch -A instead of -action
  • order makes it switchless and populated based on os.Args location index
  • require will cause hard stop when not defaulted or provided
  • environ sets all struct elements in the system envronment
  • hidden redacts the struct value in the summary report

• default: string, bool, int values

• help: description

Automatic -help support reports basic information, the struct field name, the alias is any, the env:tag in use, any default value and the help description.

 % go run example/main.go -help

 development
--------------------
 version 
 build   

 action         A     [or  ] default:           an action to do
 secret               [   *] default:           a secret
 flag                 [    ] default:on         a flag setting
 number               [    ] default:5          a number

A summary log reports the struct values and integrates with other env system. If more than one param is populated by env.NewENV(&param,&server), each will appear as seperate sets in the order provided in the log summary output.

% go run example/main.go run   
2024/07/10 21:19:54 |----------------------------------------|
2024/07/10 21:19:54 | MAIN ::::::::::::::::::::::: event log |
2024/07/10 21:19:54 |-----//o--------------------------------|
2024/07/10 21:19:54                                 version
2024/07/10 21:19:54                                 build
2024/07/10 21:19:54                             pid 65812
2024/07/10 21:19:54 |-----//o--------------------------------|
2024/07/10 21:19:54  action         | run
2024/07/10 21:19:54  secret         | <hidden>
2024/07/10 21:19:54  flag           | true
2024/07/10 21:19:54  number         | 5
2024/07/10 21:19:54 |----------------------------------------|
2024/07/10 21:19:54 _dev/srv
2024/07/10 21:19:54 sample: start
2024/07/10 21:19:55 main: bootstrap complete
2024/07/10 21:19:58 main: interrupt shutdown
2024/07/10 21:19:58 sample: stop
2024/07/10 21:19:58 main: shutdown initiated
2024/07/10 21:19:58 |----------------------------------------|
2024/07/10 21:19:58 main: bye
2024/07/10 21:19:58 |----------------------------------------|

• env.NewEnv - parse and populate a param struct

• env.Parser - parser used with NewEnv methods

• env.Dir - ensure a directory exists

• env.Expire - expiration file manager with graceful interface support

• env.Graceful - graceful interface startup/shutdown controller

• env.Lock - process file lock (simple in use detection)

• env.Persist - persist and resume with data on disk

• env.Shutdown - shutdown, not necessary with graceful controller