Environments is a new way to organize activation strategy configurations for feature toggles into separate environments. In Unleash, a feature lives across all your environments — after all, the goal is to get the new feature released as soon as possible — but it makes sense to configure the activation differently per environment. You might want the feature enabled for everyone in development, but only for yourself in production, for instance.
Previously, Unleash Enterprise could use [strategy constraints](../advanced/strategy-constraints.md) to control the rollout across environments. With the new environments feature, this is no longer necessary. Now all activation strategies belong to an explicit environment instead.
Further, connected applications will use environment-scoped API keys to make sure they only download feature toggle configurations for the environment they are running in.
Despite this being a shift in how Unleash works, everything will continue to work exactly how it did for existing users. For backwards compatibility, we have created an environment named "default" that will contain all of the existing toggles and API keys. Read more about that in [the migration section](#migration).
In order to start using environments you need to be on Unleash v4.2 or higher.
If you are on v4.2, you also need to have the environment feature enabled (if you are using Unleash Hosted, please reach out on [contact@getunleash.io](mailto:contact@getunleash.io) if you want to start using environments.
If you are on v4.3 or later, environments are already enabled for you.
Note that in order to enable an environment for a feature toggle, you must first add activation strategies for that environment. You cannot enable an environment without activation strategies.
From the “feature toggle view” you will now be able to configure activation strategies per environment. You can also enable and disable environments here. Remember that an environment must have activation strategies before you can enable it.
In order for the SDK to download the feature toggle configuration for the correct environment you will need to create an API token for a defined environment.
To ease migration we have created a special environment called “default”. All existing activation strategies have been added to this environment. All existing Client API keys have also been scoped to work against the default environment to ensure zero disruption as part of the upgrade.
If you're currently using strategy constraints together with the “environment” field on the Unleash Context, you should be aware that the new environment support works slightly differently. With environments, the SDK API will use the client's API key to determine which environment the client is configured for. The API then sends _only_ strategies belonging to the client's environment. This means that you might not need the "environment" property of the Unleash Context anymore.
We have made some slight changes to events related to feature toggles: there's one deprecation and several new event types. Most of the new events contain _project_ and _environment_ data.
To avoid missing important updates, you will also need to update your addon configuration to subscribe to the new events.
* **FEATURE-STRATEGY-ADD**¹ - An activation strategy was added to a feature toggle in an environment. The _data_ will contain the updated strategy configuration.
* **FEATURE-STRATEGY-UPDATE**¹ - An activation strategy was updated for a feature toggle. The _data_ will contain the updated strategy configuration.
In order to support configuration per environment we had to rebuild our feature toggle admin API to account for environments as well. This means that we're making the following changes to the API:
* **/api/admin/features** - _deprecated (scheduled for removal in Unleash v5.0). The [old feature toggles admin API](../api/admin/feature-toggles-api.md) still works, but strategy configuration will be assumed to target the “default” environment._
* **/api/admin/projects/:projectId/features** - New feature API to be used for feature toggles which also adds support for environments. See [the documentation](../api/admin/feature-toggles-api-v2.md) to learn more.
* Will get access to two preconfigured environments: “development” and “production”. Existing users of Unleash will also get an additional “default” environment to simplify the adoption of environments.
* Will get access to two preconfigured environments: “development” and “production”. Existing users of Unleash will also get an additional “default” environment to simplify the adoption of environments.
* Will get access to two preconfigured environments: “development” and “production”. Existing users of Unleash will also get an additional “default” environment to simplify the adoption of environments.
* Improve **Usage Metrics** to be able to show usage and evaluation results per hour for multiple days with dimensions such as environment, application and time (per hour).
* Improve **RBAC** with the ability to limit who can change configuration for a specific environment (planned as an enterprise feature).
