terraform

Commit Graph

Author	SHA1	Message	Date
Martin Atkins	b90fb25321	experiments: a mechanism for opt-in experimental language features Traditionally we've preferred to release new language features in major releases only, because we can then use the beta cycle to gather feedback on the feature and learn about any usability challenges or other situations we didn't consider during our design in time to make those changes before inclusion in a stable release. This "experiments" feature is intended to decouple the feedback cycle for new features from the major release rhythm, and thus allow us to release new features in minor releases by first releasing them as experimental for a minor release or two, adjust for any feedback gathered during that period, and then finally remove the experiment gate and enable the feature for everyone. The intended model here is that anything behind an experiment gate is subject to breaking changes even in patch releases, and so any module using these experimental features will be broken by a future Terraform upgrade. The behavior implemented here is: - Recognize a new "experiments" setting in the "terraform" block which allows module authors to explicitly opt in to experimental features. terraform { experiments = [resource_for_each] } - Generate a warning whenever loading a module that has experiments enabled, to avoid accidentally depending on experimental features and thus risking unexpected breakage on next Terraform upgrade. - We check the enabled experiments against the configuration at module load time, which means that experiments are scoped to a particular module. Enabling an experiment in one module does not automatically enable it in any other module. This experiments mechanism is itself an experiment, and so I'd like to use the resource for_each feature to trial it. Because any configuration using experiments is subject to breaking changes, we are free to adjust this experiments feature in future releases as we see fit, but once for_each is shipped without an experiment gate we'll be blocked from making significant changes to it until the next major release at least.	6 years ago

Author

SHA1

Message

Date

Martin Atkins

b90fb25321

experiments: a mechanism for opt-in experimental language features

Traditionally we've preferred to release new language features in major
releases only, because we can then use the beta cycle to gather feedback
on the feature and learn about any usability challenges or other
situations we didn't consider during our design in time to make those
changes before inclusion in a stable release.

This "experiments" feature is intended to decouple the feedback cycle for
new features from the major release rhythm, and thus allow us to release
new features in minor releases by first releasing them as experimental for
a minor release or two, adjust for any feedback gathered during that
period, and then finally remove the experiment gate and enable the feature
for everyone.

The intended model here is that anything behind an experiment gate is
subject to breaking changes even in patch releases, and so any module
using these experimental features will be broken by a future Terraform
upgrade.

The behavior implemented here is:

- Recognize a new "experiments" setting in the "terraform" block which
  allows module authors to explicitly opt in to experimental features.

  terraform {
    experiments = [resource_for_each]
  }

- Generate a warning whenever loading a module that has experiments
  enabled, to avoid accidentally depending on experimental features and
  thus risking unexpected breakage on next Terraform upgrade.

- We check the enabled experiments against the configuration at module
  load time, which means that experiments are scoped to a particular
  module. Enabling an experiment in one module does not automatically
  enable it in any other module.

This experiments mechanism is itself an experiment, and so I'd like to
use the resource for_each feature to trial it. Because any configuration
using experiments is subject to breaking changes, we are free to adjust
this experiments feature in future releases as we see fit, but once
for_each is shipped without an experiment gate we'll be blocked from
making significant changes to it until the next major release at least.

1 Commits (a978d4ee99048967895eb48a208e731e5b00a36f)