react-native-environments-guide

According to the twelve-factor app guidelines:

an app’s config is everything that is likely to vary between deploys (staging, production, dev).

Moreover, a twelve-factor app:

requires strict separation of config from code. Config varies substantially across deploys, code does not.

In the context of a React Native app, this means having:

1. a bunch of .env files, one for each environment
2. a script to build the app for a specific environment (and platform).

In the end, I want to make a build with a command-line invocation, like this:

fastlane ios build --env production

where env can be production, staging or dev.

To achieve this, I'll use react-native-config, Xcode build schemes and Android product flavors.

• Start here
• Setup iOS
• Setup Android
• Write the build scripts
• (Bonus) Validate env variables

Start here

First, let's make sure we are on the same page. For this particular guide, I'm using the following package versions:

[email protected]
[email protected]

I want to set up 3 environments: dev, staging and production. The naming is completely arbitrary, it can be anything you prefer (like local, alpha and release, as another example).

I'm creating a new env directory, where I'll place these three .env.* files.

mkdir env
touch ./env/.env.dev ./env/.env.staging ./env/.env.production

And in the project's root, an empty .env file, which I'll add add to .gitignore:

touch .env
echo ".env" >> .gitignore

[!IMPORTANT] -- Why do I add it to .gitignore? The main .env will be the working file, changed before every build to contain the desired environment variables. Considering its volatile nature, it's not something we want to track in source control.

Now the directory structure looks like this:

/example
  /env
  ├── .env.dev
  ├── .env.production
  └── .env.staging
  .env
  ...

[!TIP] -- using tree to pretty-print the directory content.

Setup iOS

I'm relying on Xcode build schemes to create one scheme per environment.

Setup Android

TODO