Proposal: gate non-stable features behind a flag

[rfratto]

Background

Non-stable features are documented as such, but there's nothing preventing a user from using the feature. This can be a problem if a user didn't realize the feature was non-stable, and would either prefer to only use stable features or are running the agent in a corporate environment where non-stable features aren't permitted.

This proposal outlines an approach to help users avoid accidentally using features with an undesired stability level.

Proposal

I propose a new flag to grafana-agent run which specifies the minimum stability of features that can run in that process:

--stability.level=experimental # allow usage of experimental, beta, and stable features 
--stability.level=beta         # allow usage of beta and stable features 
--stability.level=stable       # allow usage of stable features 

If a Flow config file or any loaded module uses a feature at a level lower than the minimum stability level, that config file or module should fail to load.

As part of this proposal, code will need to be updated to reflect the stability level of various things. To start with, the following will support stability levels:

• Components
• Component blocks
• Component attributes
• Services

In the future, the stability concept may be extended to include language-level features or standard library functions in River.

If this proposal is accepted, the default value should be --stability.level=experimental for backwards compatibility with existing users. The default value should be changed to --stability.level=stable alongside the eventual 1.0 release.

[rfratto]

Proposal has been accepted following an offline vote by maintainers.