Enable experimental features runtime

[sagikazarmark]

Preflight Checklist

• I have searched the issue tracker for an issue that matches the one I want to file, without success.

Problem Description

Consumers may want to enable experimental features runtime. Although it may not always be possible, it should be doable for the most part.

Proposed Solution

Introduce a new API to enable feature flags in Viper.

Something like:

v := viper.New(viper.Enable("bind-struct"))

The nice thing about this API is that it's generic and it doesn't necessarily break once an experiment is rolled out as a fully functional feature.

The counterpart of Enable should be Disable, so users can go back to the old behavior while it's still available.

Alternatives Considered

Other potential names:

• EnableFlag/DisableFlag
• EnableExperiment/DisableExperiment
• Enable(Experimental)Feature/Disable(Experimental)Feature

Additional Information

Came up in #1706 (comment)

[github-actions]

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[mazenharake]

imho, I think I would prefer viper.New(viper.EnableBindStruct(), ...). I would also reckon it is easier to maintain since as more features are released then the viper.Enable("...") could become bloated. Since this is going to become a part of the API then it is clearer to know what Options there are by simply looking at the exported Options rather than to look up a string in the documentation.

just my 2 cents, either would be fine though.