env: A Go repository from davecheney

#GAE Environment Variable Library#

Available under the MIT (Expat) License - see bottom of README.

Rationale

Mapping GAE Projects to Programming Environments

A simpler way of thinking about programming environments when working with `appengine.Context' AppIDs (or Project IDs) on Google's Cloud Platform, GAE

So, instead of

func SomeHandler(c appengine.Context, w http.ResponseWriter, r *http.Request) {
	if appengine.AppID(c) == "rockpool-production" {
		//do this
	} else if appengine.AppID(c) == "rockpool-staging" {
		//do that
	}

you can do this

func SomeHandler(c appengine.Context, w http.ResponseWriter, r *http.Request) {
	if env.Is("production") {
		//do this
	} else env.Is("staging") {
		//do that
	}

As well as being cleaner, it means you can meaningfully refer to environments in your code without having to hardcode the name of the Google Cloud Project.

Environment Specific Variables

You may then access environment specific variables with env.Get(c, appengine.Context, key string) or env.GetOk(c, appengine.Context, key string):

func SomeHandler(c appengine.Context, w http.ResponseWriter, r *http.Request) {
	db_password := env.Get(c, "db_password").(string)
	//or, use the GetOk pattern
	db_password2, ok := env.GetOk(c, "db_password")
}

Example JSON Config

{
    "mappings" : {
        "production" : "rockpool-production",
        "staging" : "rockpool-staging",
        "test" : "rockpool-test"
    },
	"default" : {
		"question" : "How about a nice game of chess?",
	},
	"production" : {
		"message" : "I am a production Msg",
		"tolerance" : 0.12,
		"acceptableRank" : ["2","3","4"]
	},
	"staging" : {
		"message" : "I am a staging Msg",
		"tolerance" : 0.13,
		"acceptableRank" : ["5","6","7"]
		"question" : "How about a nice game of chess (in staging)?",
	}

The default stanza

Default variables mean that every environment will gain this value, unless they choose you choose to override it within the environment's stanza.

In the example configuration above, production will have a question with "How about a nice game of chess?" as its value but staging will have "How about a nice game of chess (in staging)?".

How to load the JSON config

Typically setup is down within a init function called early in the lifecycle of one of your packages.

Use MustLoad to create a runtime panic if the JSON config cannot be loaded. Use Load to return an error to handle yourself if the JSON config cannot be loaded.

func init() {
	env.MustLoad("./environment.json")
	// or ...
	err := env.Load("./environment.json")

	if err != nil {
		...
	}
}

Installation

goapp get github.com/rockpoollabs/env

Also see Configuration below.

Godoc

http://godoc.org/github.com/rockpoollabs/env

Configuration

You will need to be setup with google app engine and goapp. See the google app engine documentation for details

Dependencies are installed via:

make deps

Testing

make test
make live-test //then browse to http://localhost:8080/

Formatting

make fmt

Development

Ensure that you are running Goapp. This was developed on goapp 1.9.15 but should work with earlier versions supporting appengine.AppId.

	goapp version
	go version go1.2.1 (appengine-1.9.15) darwin/amd64

Contributing

You're welcome to make a Pull Request; please include tests for anything you want to contribute.

MIT License

The MIT License (MIT)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

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 OR COPYRIGHT HOLDERS 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.

davecheney/env