Feature for disabling specific runtimes

[agocke]

Sometimes there are changes in new runtimes that require investigation. For large deployments, removing the runtime can be expensive. A feature flag (file, environment variable?) would provide a quick way to effectively rollback a runtime installation.

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[jkotas]

A feature flag (file, environment variable?) would provide a quick way to effectively rollback a runtime installation.

For a specific apps(s), or for the whole machine?

The roll forward settings (DOTNET_ROLL_FORWARD env variable, etc.) are meant to enable this sort of scenarios - https://learn.microsoft.com/en-us/dotnet/core/tools/dotnet-environment-variables.

[agocke]

For a specific apps(s), or for the whole machine?

The whole machine, or rather a fleet of whole machines. The idea is that the entire fleet can immediately disable a particular runtime on the entire fleet without reimaging.