launch

README

Launch

Lightly Wrapped Envconfig for your Golang main

Why?

Why wrap the excellent envconfig module?

• "-h" flag for a list of environment variables of interest
• "-c" flag to show what would be loaded from environment
• Redact type for not disclosing sensitive strings via json.Marshal
• demonstrate super handy Config pattern for packages
• top-level error checking
• b-but mostly to test and reuse this surprisingly fiddly code

Help Flag

launch % go run github.com/clarktrimble/launch/examples/thingone -h
This application is configured via the environment. The following environment
variables can be used:

KEY                   TYPE       DEFAULT    REQUIRED    DESCRIPTION
DEMO_THINGTWO         String     bargle
DEMO_TOKEN            Redact                true
DEMO_SVC_IMPORTANT    String                true
DEMO_SVC_NOTSOMUCH    Integer    42

Copy and paste from here into env file!

Config Flag and Redact

launch % source examples/thingone/demo.env
launch % go run github.com/clarktrimble/launch/examples/thingone -c
{
  "version": "",
  "thing_two": "thingone",
  "token": "--redacted--",
  "svc_layer": {
    "important": "Brush and floss every day!",
    "not_so_much": 42
  }
}

Nice for a quick sanity check!

Config Pattern

From package:

type Config struct {
  Important string `json:"important" required:"true"`
  NotSoMuch int    `json:"not_so_much" default:"42"`
}

func (cfg *Config) New() (svc *SvcLayer, err error) {
  // ...
  return
}

In main:

type Config struct {
  // ...
  Version  string           `json:"version" ignored:"true"`
  Svc      *svclayer.Config `json:"demo_svc"`
}
// ...

cfg := &Config{Version: version}
launch.Load(cfg, cfgPrefix)
// ...

svc, err := cfg.Svc.New()
launch.Check(context.Background(), lgr, err)
// ...

So yeah, such packages are "dependent" on the pattern, but feels like a reasonable 80/20 trade-off so long as confined to the service-layer (ala Clean Architecture).

Check

Heresy perhaps, but at the top one checks for errors. Nice to capture this in the logs where possible.

Test, Build, and/or Run

launch % go test --count=1 ./...
launch % go run github.com/clarktrimble/launch/examples/thingone

or

proj/launch % make build
:: Done
proj/launch % make test
CGO_ENABLED=0 go test -count 1 ./...
?   	github.com/clarktrimble/launch/examples/thingone	[no test files]
?   	github.com/clarktrimble/launch/examples/thingone/minlog	[no test files]
?   	github.com/clarktrimble/launch/examples/thingone/svclayer	[no test files]
ok  	github.com/clarktrimble/launch	0.130s

Golang (Anti) Idioms

I dig the Golang community, but I might be a touch rouge with:

• multi-char variable names
• named return parameters
• BDD/DSL testing

Todo: spellcheck my man!

All in the name of readability, which of course, tends towards the subjective.

License

This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.

In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain. We make this dedication for the benefit of the public at large and to the detriment of our heirs and successors. We intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

For more information, please refer to http://unlicense.org/

Documentation

Overview

Package launch lightly wraps the lovely envconfig for main

Index

• func Check(ctx context.Context, lgr Logger, err error)
• func Load(cfg any, prefix string, usage string)
• type Logger
• type Redact
  • func (redact Redact) MarshalJSON() ([]byte, error)

Functions

func Check

func Check(ctx context.Context, lgr Logger, err error)

Check exits when error is not nil

func Load

func Load(cfg any, prefix string, usage string)

Load looks for help flags and loads the config from env

-h for help (handly for writing env file!) -c to show config that would be loaded from the current env

Types

type Logger

type Logger interface {
	Error(ctx context.Context, msg string, err error, kv ...interface{})
}

Logger is a logging interface

type Redact

type Redact string

Redact is a type for private strings

func (Redact) MarshalJSON

func (redact Redact) MarshalJSON() ([]byte, error)

MarshalJSON implements the Marshaler interface