Create DAppNode Anchor package

[chong-he]

This is the PR to create a DAppNode package for Anchor. It currently only has anchor node ability to run a SSV node. It supports importing an existing encrypted private key. Tested and the package is able to start Anchor and use the imported key successfully. However I am sure there are still some fine details/bugs that can be tuned/improved.

[chong-he]

I think the current package is in a pretty good form. Tested and it works mostly, except for a bug that: currently for importing existing keys, it requires a manual restart in the first time. Details below:

When importing existing operator key, user will upload the private key encrypted_private_key.json, and provide password in the web UI. It seems that there is some race condition happens where the private key is yet to be detected by Anchor:

2026-02-02T07:02:16.186620Z  INFO Starting the Anchor client                        beacon_nodes=["http://beacon-chain.hoodi.dncore.dappnode:3500/"] execution_nodes=["http://execution.hoodi.dncore.dappnode:8545/"] execution_nodes_websocket="ws://execution.hoodi.dncore.dappnode:8546/" data_dir=/root/.anchor version="Anchor/v1.2.0"
2026-02-02T07:02:16.187094Z  INFO Creating private key
2026-02-02T07:02:16.214625Z  INFO Shutting down...                                  reason=Success("Received SIGTERM")
2026-02-02T07:02:16.317737Z  INFO Saving encrypted private key                      file=/root/.anchor/encrypted_private_key.json
2026-02-02T07:02:16.969752Z ERROR Failed to start Anchor                            reason="Unable to write encrypted private key: File exists (os error 17)"

We see that Anchor is creating a new private key. This only happens when we run anchor node and it does not detect a private key in the data directory. But, soon after, the creation of private key failed with error:

File exists

i.e., the private key exists. This is when it detects that the private key is there. Anchor shuts down, but it does not auto restart although in docker-compose.yml, the restart: unless-stopped is set. When the user manually clicks restart, then Anchor will run as usual (with the uploaded private key, not a new private key). It will be nice to have this bug solved so that users will have a seamless experience if they migrate their keys to Anchor using DAppNode. Currently waiting for reviews and feedback.