The original purpose of the fee_recipient_file was to allow the user to change a validator's fee_recipient on the fly (that is, without restarting the validator client).

But there is now a new validator keymanager API endpoint for doing this. See:

• Implement feerecipient API for keymanager (VC) #3173
• [Merged by Bors] - Implement feerecipient API for keymanager #3213

In order to implement this API endpoint, we must persist changes to the fee_recipient made via the API in the validator_definitions.yml file. This will automatically override the settings in the fee_recipient_file.

So this endpoint not only makes the fee_recipient_file unnecessary, it makes it useless if the API endpoint is used.

Furthermore, in the future, there will be additional configuration options that can be set on a per-validator basis (like the gas_limit). There's no point in having the fee_recipient be the only option that is set via a file, nor do we want to implement a new file type for each setting as it would become tedious to manage, especially when there are these API endpoints to change them.

We should remove the --fee_recipient_file functionality and manage these changes entirely via API endpoints. For options that don't yet have an official endpoint we should utilize a PATCH endpoint.

We should remove this before the merge as most people will not have added it to their workflows yet.