spf13--viper/docs/adr/0005-deprecate-setters-in-favor-of-functional-options-during-initialization.md

5. Deprecate setters in favor of functional options during initialization

Date: 2021-07-20

Status

Proposed

Context

The Viper struct currently acts as a facade for reading, writing and watching configuration for changes. Some of the configuration parameters can be changed runtime using setters which often lead to issues with concurrent activities.

Decision

Deprecate setters in favor of using functional options for configuring Viper when it's initialized.

Drop setters in Viper 2.

Consequences

Since Viper's interface is usually invoked from a lot of places, moving configuration to the place where it is initialized makes using Viper safer (ie. someone can't just randomly call Set when they are only supposed to call Get*).

This change will also clarify what roles Viper can be used in and makes the separation of internal components easier based on these roles.