detect-environment/guides/gulp-integration/travis.md

Detect environments in JavaScript similar to the way Laravel does

# Working with travis

When you want your environment variables to be present inside your [travis](https://travis-ci.org)
builds, but not be present in your repositories history, you can leverage
travis's own [environment variables](http://docs.travis-ci.com/user/environment-variables/#Using-Settings).

## Configuring travis

To add variables to your build navigate to your repo on travis and then head to
the `/settings/env_vars` page. The url should be somthing like:

> https://travis-ci.org/<username>/<reponame>/settings/env_vars

You will need to do this for every value in your `.env` files. Next you will
need to add a new variable for each variable in your `.env` file. Follow the
steps below to add new variables.

1. Click `Add a new variable`.
2. Set `Name` and `Value`.
3. Optionall check `Display value in build logs`.

By checking `Display value in build logs` a log will appear in the travss build
like so:

```sh
$ export TRAVIS_FOO=TRAVIS_BAR
```

Otherwise you will see:

```sh
$ export TRAVIS_FOO=[secure]
```

Either way the value is set all the same.

## Working locally

Given the following `.env` file,

```yml
# .env.testing.yml
---
    key:    "12345678123456781234567812345678"
    secret: "abcdefghabcdefghabcdefghabcdefgh"
```

To reproduce the variables within the travis environment, add two new
environment variables to travis by navigating the the example url below.

> https://travis-ci.org/<username>/<reponame>/settings/env_vars

In accordance with the `.env.testing.yml` file we need to add two variables to
travis. These variables should be namespaced so as to not run into any
collisions with other variables. Example input is provided below

| Name          | Value                            |
| :------------ | :------------------------------- |
| TRAVIS_KEY    | 12345678123456781234567812345678 |
| TRAVIS_SECRET | abcdefghabcdefghabcdefghabcdefgh |

Because the JavaScript environment that travis is run is just an ordinary `node`
environment, we can use nodes build in [`process.env`](http://nodejs.org/api/process.html#process_process_env)
variable to gain access to the above defined environment variables.

Consideer the following code snippet.

```js
console.log(process.env.TRAVIS_KEY);    // 12345678123456781234567812345678
console.log(process.env.TRAVIS_SECRET); // abcdefghabcdefghabcdefghabcdefgh
```

Because the vm that travis runs its tests on is just an ordinary linux
environment, we can exploit that fact and test to see if certain directories
exist. The `$HOME` directory exposed by travis is `/home/travis`.

We can us the node [`fs`](http://nodejs.org/api/fs.html) module to test to see
if this directory exists[[1]](#travis-warning), and if it does we can have a
reasonable level of confidence that we are running from within the travis
environment.

```js
// gulpfile.js

// Pull in any system pacakges.
var fs = require('fs');

// Pull in `gulp` and its plugins.
var gulp = require('gulp');
var gutil = require('gulp-util');

// Pull in the `detect-environment` plugin.
var de = require('detect-environment');

// Determine our environment name and fetch its data.
var env = de(function (envName, envData) {
    if (fs.existsSync('/home/travis')) {
        gutil.log('Travis detected. Setting environment to "testing"');
        envData.key    = process.env.TRAVIS_KEY;
        envData.secret = process.env.TRAVIS_SECRET;
        return 'testing';
    }
    return envName;
});
```

In the `de()` callback we check to see if we are running from within the travis
vm by checking to see if the `/home/travis` directory exists. If it is found to
exist we attach the required variables to the `envData` Object.

Modifying the `envData` Object works the same way that modifying the `exports`
variable inside a node package works.

These additions to the `envData` Object will override any values present in a
local `.env` file. But since no `.env` file will exist on the travis box this is
a moot point.

---
###### <sub>Travis warning</sub>
<sub>The travis docs advise against using this as a form of detection due to the
possibility of the directory changing at any point of time. This is however very
very unlikely to be changed. Check their [docs](http://docs.travis-ci.com/user/ci-environment/)
form more info.</sub>