nimbus-eth1/nimbus_verified_proxy/docs/metamask_configuration.md

MetaMask configuration with Alchemy provider

This document explains how to configure the proxy, and how to configure MetaMask to make use of the proxy.

1. Building the Nimbus Verified Proxy

First build the Nimbus Verified Proxy as explained here.

2. Configuring and running the Nimbus Verified Proxy

To start the proxy for the Goerli network, run the following command (inserting your own TRUSTED_BLOCK_ROOT and Alchemy API_KEY):

# From the nimbus-eth1 repository
TRUSTED_BLOCK_ROOT=0x1234567890123456789012345678901234567890123456789012345678901234 # Replace this
API_KEY=abcd # Replace this
./build/nimbus_verified_proxy \
    --network=goerli \
    --trusted-block-root=${TRUSTED_BLOCK_ROOT} \
    --web3-url="wss://eth-goerli.g.alchemy.com/v2/${API_KEY}"

After startup, the Nimbus Verified Proxy will start looking for suitable peers in the network, i.e peers which serve consensus light client data, and will then start syncing. During syncing most of the RPC endpoints will be inactive and will fail to respond to queries. This happens because the proxy cannot verify responses from the data provider until the consensus light client is in sync with the consensus chain.

When the consensus light client is in sync, the following line should be visible in the logs:

NOT 2022-09-29 10:06:15.974+02:00 New LC optimistic block                    opt=81de61ec:3994230 wallSlot=3994231

After receiving the first optimistic block, the proxy is ready to be used with MetaMask.

3. Configuring MetaMask extension to use a custom network

To add custom network in MetaMask browser extension:

1. Go to MetaMask settings.
2. In settings, go to networks tab.
3. Click on the Add a network button.
4. Click on Add a network manually.
5. Type a Network name of choice, e.g. "Trusted Goerli". The New RPC URL field must be configured to point to the HTTP server of the proxy. In this example it will be http://127.0.0.1:8545. The Chain ID field must be set to the chain id of the network used by the proxy. The chain id for Goerli is 5.

If everything went smooth there should be a new network in Networks drop down menu.

After switching to this network it should be possible to create new accounts, and perform transfers between them.

Note: Currently, adding a custom network with a chain id which already exists in the MetaMask configuration will be highlighted as an error. This should be ignored as this should be rather a warning, and is a known bug in MetaMask.