Forking

Forking is the mechanism by which workloads are deployed into a Sandbox. At a high level, it takes a baseline workload, applies some customizations to it and creates a new workload called the forked workload that is tied to the Sandbox Environment.

Forking relies on the idea that when it comes to testing a microservice, only a small portion of its specification changes against its baseline (stable) version. Concretely, if all we were testing was a new docker image for a microservice, the specification of a fork looks as below:

  forks:
  - forkOf:
      kind: Deployment
      namespace: ...
      name: ...
    customizations:
      images:
      - image: ...
      ...

The baseline workload (Deployment in this case) that we want to derive from is specified under forkOf, identified by its namespace and name. When a sandbox containing the above fork specification is created, it will automatically use that baseline workload's runtime specification in Kubernetes, apply the specified customizations and then derive a new forked version of that Deployment that is specific to the Sandbox. Note that the baseline workload is never modified as part of this process.