Configure your experiment

The first step in creating an experiment is to configure it. Configuring is a brief, two-step process: first you’ll create an environment, then you’ll install the SDK you want to use.

Create an environment

In Amplitude Experiment, an environment is where you can serve a group of flags or experiments for code execution. Once you create an environment, Experiment will generate an access key, which you can then use to properly route your flags and experiments.

Environments live under Amplitude Analytics projects. A project can have multiple environments, but each environment can only be attached to a single project.

To create an environment, follow these steps:

1. From inside Experiment, click Environments in the left-hand rail. Then click + Add Environment. 
2. Choose the Amplitude Analytics project you’d like the environment to be associated with. If you want to create environments in multiple projects at once, just select all the relevant projects from the drop-down list.
3. Next, choose a name for your environment and specify its type:

• • • • Client-side: These environments run on a client device, such as a web browser or mobile app. The API key associated with client environments can be viewed publicly and should be used in client-side SDKs.
      • Server-side: These environments run on a server you control, such as a web server or batch processing system. The API key associated with server environments should be kept secret and are for use in server-side SDKs. Server-side keys can access the REST API for flag evaluation. If, instead of running a full-blown experiment, you only need to evaluate flags using the REST API, you should create a server-side environment.
      • Secret: These environments run on a server you control. The API key associated with secret environments should be kept secret. Secret keys have access to the full REST API. If you need to use the REST API for more than just flag evaluation, you should create a secret environment.

4. Click Add Environment. Amplitude Experiment will create your environments and automatically generate keys to copy and use.

Install the SDK

If you’re not planning to use the REST API, the next step is to install the SDK. Each SDK has different installation instructions, which you can find by clicking through these links:

• Browser JS (Client)
• Node JS (Server)
• Android (Client)
• iOS (Client)
• React Native (Client)

All SDKs send a request to Amplitude Experiment to determine what flag configurations should be served to a particular user. That said, there are some important differences between client-side and server-side SDKs you should be aware of.

Client-side SDKs are meant to be run in the end-user application environment. When choosing between client-side and server-side, keep in mind that client-side SDKs:

• Assume a single user environment
• Use client-side API Keys, which are public and visible to end users
• Fetch variants up front for a given user
• Store variants locally on the client for offline mode

Server-side SDKs, on the other hand, are meant to be run in a server environment. Server-side SDKs:

• Assume a multi user environment
• Use Server-side API Keys, which should be kept private
• Fetch variants on each request

The User context

When assigning variants, the evaluation engine applies the targeting rules to a user context object. This object represents the identity of an individual user. In client-side SDKs, this object-user relationship is set on initialization and passed to the server on every request for variants. In server-side SDKs, the user may change, and should be set on every request.

When targeting individual users to allocate variants, Experiment will match on any of the listed user IDs ( user_id ) or device IDs ( device_id ). Using rule-based user segments will match on any of the predefined properties (country, platform, etc.), or on custom properties specified in the user_properties object.

JSON:

{
  "user_id": "Amplitude User ID",
  "device_id": "Amplitude Device ID",
  "country": "Country",
  "region": "Region",
  "city": "City",
  "dma": "DMA"
  "language": "Language",
  "platform": "Platform",
  "version": "Version",
  "device_family": "Device Family",
  "device_type": "Device Type",
  "carrier": "Carrier",
  "user_properties": {
    // you can attach custom user properties here
  }
}

NOTE: You should use the same user identifiers (device ID and user ID) for Amplitude Experiment that you use for sending data to Amplitude Analytics. This way, identities will be resolved correctly, and data generated will be correctly associated with the same user in Analytics.