eth-docker supports using ethdo in an online/offline fashion to prepare withdrawal credential changes files. This follows the ethdo instructions for this process.
Do NOT under any circumstances enter your mnemonic into a machine that is online or used for daily tasks
Metrika will let you see whether your validator has a withdrawal address set. If yes, that is where consensus layer rewards will be swept automatically (every 4-5 days at ~500,000 validators total) and where your funds will be sent when exiting.
You can use ./ethd keys list to get a list of your validator public keys that are currently active on your system.
On your machine running eth-docker, run ./ethd keys prepare-address-change.
Under the hood this will run ethdo --connection <FIRST_CL_IN_CL_NODE> --allow-insecure-connections validator credentials set --prepare-offline
which creates an offline-preparation.json file in ./.eth/ethdo.
This file contains a list of all validators currently on the network and is necessary for the offline machine.
This command will also download ethdo itself into this directory.
Copy the contents of this directory, including this README.md, ethdo, ethdo-arm64, the offline-preparation.json, and the create-withdrawal-change.sh script, to a USB stick (we will call it Data USB).
You should also create a new text file on the Data USB that contains the address you want your validator rewards to go to. This has to be an address you control. Good choices are a hardware wallet where the mnemonic was never online or a contract such as a multi-signature safe.
Triple-check the withdrawal address you choose! You can only set this once
If you do not provide the address through a USB stick you will have to type it manually which is prone to human error.
Get the Ubuntu Desktop ISO and burn it to a second USB stick (we will call it Live USB) with Balena Etcher or Rufus.
Plug in the Live USB to your offline computer and turn it on. You will likely need to override the boot target in the UEFI(BIOS) settings. Methods to do this vary by device: Common key interrupts are F2, F8, F12, DEL and Enter. While you are updating the boot target, it would be proper to additionally turn off WIFI, Bluetooth and LAN integrated devices.
Upon saving those settings and exiting the UEFI(BIOS) interface, you will be prompted with a list of options. Choose "Try Ubuntu". Do not install Ubuntu.
After Ubuntu loads, insert the Data USB that holds ethdo and the other files from the Offline preparation step.
Verify your internet has been disabled by attempting to visit a website, ping through terminal, or looking in the upper right corner of the desktop.
Open a "Terminal", and cd to the Data USB directory. It will likely be in /media/ubuntu/USBNAME. You can use the Files app and right-click the USB, then look at Properties, to see where it is mounted.
Run bash create-withdrawal-change.sh.
You will be prompted to specify the withdrawal address you want your funds to be sent to. You should copy that value from the text file.
Triple-check the withdrawal address you set here! You can only set this once
You will then be prompted to provide the mnemonic or "seed phrase" of your validator(s). This is needed to sign the change withdrawal request. To clarify, this is the mnemonic of the validators' "withdrawal key", which, if you used staking-deposit-cli to make the keys, is also the mnemonic of your validator signing keys. It is not the mnemonic of the depositing address, or the withdrawal address.
A file change-operations.json will then be created and saved on the Data USB for use with eth-docker and ethdo on your online computer.
Shut down Ubuntu which will make your PC "forget" anything it knew about your mnemonic during this process.
At this point your Live USB will no longer be needed.
Did I mention to triple-check the withdrawal address you have set? You can only set this once!
Go to https://beaconcha.in/tools/broadcast and drag-drop the change-operations.json file in. It will be broadcast to the chain.
Insert the Data USB to your online computer where eth-docker is running.
Copy the change-operations.json from the Data USB to ./.eth/ethdo on your eth-docker node.
Run ./ethd keys send-address-change. You will have one more chance to verify your withdrawal address.
Did I mention to triple-check the withdrawal address you have set? You can only set this once!
If a Shanghai/Capella fork has been announced on your chain, the changes will be loaded into the consensus layer client for broadcast. If Shanghai/Capella is live, they will be broadcasted. Inclusion should take ~3 days after the hardfork date if everyone piles in at once or should be almost immediate if you have waited.
Obsessively refresh Metrika to see whether your validator now has a withdrawal address set. If yes, that is where consensus layer rewards will be swept automatically every 4-5 days at ~500,000 validators total.
You can use ./ethd keys list to get a list of your validator public keys that are currently active on your system.