Ethereum Protocol Fellowship - The Third Cohort (Update 10)

Long term topic I'm working on

Rewrite the validator client code to be compatible with the Beacon API instead of prysmaticlabs' internal API.

Ticket here.

Actions done

GetFeeRecipientByPubKey

I wrote this (merged) PR:

What does this PR do? Why is it needed?

This PR introduces two main changes:

FeeRecipientconfig

In ProposerOption, a new wrapper FeeRecipientConfig around FeeRecipient is created:

type FeeRecipientConfig struct {
	FeeRecipient common.Address
}

// ProposerOption is a Prysm internal representation of the ProposerOptionPayload on the validator client in bytes format instead of hex.
type ProposerOption struct {
	FeeRecipientConfig *FeeRecipientConfig
	BuilderConfig      *BuilderConfig
}

This change enables the fact that FeeRecipient could be undefined while BuilderConfig is defined.
This fixes https://github.com/prysmaticlabs/prysm/issues/11948.

This PR ensures PrepareBeaconProposer and SubmitValidatorRegistrations are called only for pubkeys with a (custom or default) fee recipient.

==> We can call POST setGasLimit on a pubkey without fee recipient without automatically defined the corresponding fee recipient to burn address.

GetFeeRecipientByPubKey

Before this PR, GetFeeRecipientByPubKey gRPC call is called in:

• SetGasLimit,
• SetFeeRecipientByPubkey, and
• ListFeeRecipientByPubkey

There is no (direct or indirect) equivalent of GetFeeRecipientByPubKey in Beacon API.
The idea of this PR is to reduce usage of GetFeeRecipientByPubKey gRPC call as low as possible.

After this PR, GetFeeRecipientByPubKey gRPC is only used in ListFeeRecipientByPubkey.
A next PR will handle this last case in order to be fully Beacon API compatible.

Also, I wrote this (not yet merged) PR:

What does this PR do? Why is it needed?

This PR deals with the (lack of) implementation for the GetFeeRecipientByPubKey method in beacon API.

With gRPC implementation, if, for a given {pubkey}:

• no {pubkey} specific fee recipient is set in validator client, AND
• no default fee recipient is set in validator client, AND
• the GetFeeRecipientByPubKey gRPC beacon API call responds on error, then:

Before this PR, the call to GET /eth/v1/validator/{pubkey}/feerecipient returns the burn address 0x0000....
After this PR the call to GET /eth/v1/validator/{pubkey}/feerecipient returns:

{
    "message": "Failed to retrieve default fee recipient from beacon node",
    "code": 500
}

With gRPC implementation, if, for a given {pubkey}:

• no {pubkey} specific fee recipient is set in validator client, AND
• no default fee recipient is set in validator client, AND
• the GetFeeRecipientByPubKey gRPC beacon API call responds with a nil value or with an empty value, then:

Before this PR, the call to GET /eth/v1/validator/{pubkey}/feerecipient returns the burn address 0x0000....
After this PR the call to GET /eth/v1/validator/{pubkey}/feerecipient returns:

{
    "message": "No fee recipient set",
    "code": 400
}

With beacon API implementation, if, for a given {pubkey}:

• no {pubkey} specific fee recipient is set in validator client, AND
• no default fee recipient is set in validator client, then:

the call to GET /eth/v1/validator/{pubkey}/feerecipient returns:

{
    "message": "No fee recipient set",
    "code": 400
}

Warning:
The 400 and 500 code listed above will cause, in Prysm validator WebUI, the following error:

Because this PR breaks the Prysm validator client WebUI, it is marked as blocked waiting for the Prysm validator client WebUI (which is in another git repo) update.