Routing traffic

How Release routes traffic to your environments

When you create environments on Release, we generate hostnames that are instantly available, unique, and predictable.

Instant domain updates

Traditional DNS is too slow for the fast-paced traffic routing required when creating ephemeral environments.

To avoid having to wait for DNS propagation every time you launch a new environment, Release uses a proprietary Lambda@Edge routing infrastructure that makes domain updates instant.

Each incoming request to CloudFront runs a Lambda@Edge function to check the request URL against a routing table stored in DynamoDB so that Release can instantly route and reroute traffic to your environments.

For dynamic services such as web servers or APIs, Release creates a routing entry that points requests to the Application Load Balancer for your environments' Kubernetes clusters.

For static sites, Release takes the bucket hostname and path, including a list of any assets written to S3 for the version being deployed, and adds those entries to our routing table.

Release takes care of maintaining this routing table when you create or delete environments.

How Release creates unique hostnames

If you're a self-hosted user with a custom domain, say,, hostnames for your ephemeral environments will follow this pattern:


Here is an example hostname for an app called portal and a service called api:

Creating predictable hostnames using environment handles

You can create environment handles to replace the random string in an environment's hostnames. This enables Release to create, or re-use, unique hostnames from a pre-determined list.

This is useful for services where it is expected that hostnames are known in advance, for example, when manually whitelisting callback domains at your OAuth provider.

When an environment is deleted, the environment handle used for the environment's hostname is returned to the pool of available handles and can be re-used for new environments.

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