Gnosis Chain with an external CL

Alternatively, you can also run a Gnosis Chain node as an Execution Layer (EL) and couple it with an external Consensus Layer (CL). Here is an example of configuration with Lighthouse.

1. Start Erigon:

Start Erigon adding the --externalcl flag.

erigon --chain=gnosis --externalcl

If your CL client is on a different device, add the following flags:

• --authrpc.addr <this-host-LAN-IP> — the Engine API listens on localhost by default, so it has to be widened for a remote CL. Read the warning below before reaching for 0.0.0.0;
• --authrpc.vhosts <CL_host> where <CL_host> is the source host or the appropriate hostname that your CL client is using.

warning

The Engine API drives block processing, so anything that can reach it and holds your JWT secret controls the node. Only widen it when the CL really is on another machine, and protect the endpoint when you do:

• prefer the specific interface — --authrpc.addr <this-host-LAN-IP> — over 0.0.0.0, which listens on every interface including any public one;
• restrict port 8551 at the firewall to the CL host's address, and never expose it to the internet;
• treat --authrpc.vhosts as a Host-header check, not a network control: it is not a substitute for a firewall rule;
• keep jwt.hex readable only by the accounts that need it, and copy it to the CL host over a private channel.

2. Install Lighthouse

Install Lighthouse, following instructions at https://lighthouse-book.sigmaprime.io/installation.html.

The official pre-built binaries already support Gnosis Chain and Chiado, so no special build is required. You can confirm this with lighthouse --help, which lists gnosis and chiado among the accepted --network values.

tip

Track Lighthouse releases and keep it current, the same way you would Erigon. Beyond fixes and performance work, a consensus client carries the fork schedule it was built with: a version released before an upcoming hard fork may not follow the chain through it, which stalls your execution layer too. Watch the Lighthouse releases page and upgrade before scheduled forks, not after.

note

Only if you build Lighthouse from source do you need to enable the Gnosis Chain support explicitly, since it is not one of the default Cargo features:

env FEATURES=gnosis make

3. Sync Lighthouse to a public checkpoint

Because Erigon needs a target head in order to sync, Lighthouse must be synced before Erigon can synchronize. The fastest way to synchronize Lighthouse is to use one of the many public checkpoint synchronization endpoints, for example:

1. https://checkpoint.gnosischain.com for Gnosis Chain;
2. https://checkpoint.chiadochain.net for Chiado testnet.

4. Set the Erigon JWT secret path in Lighthouse

To communicate with Erigon, the execution endpoint must be specified as <erigon address>:8551, where <erigon address> is either http://localhost or the IP address of the device running Erigon.

1. Lighthouse must point to the JWT secret automatically created by Erigon in the --datadir directory. In the following example the default data directory is used.

   lighthouse bn \
   --network gnosis \
   --datadir=data \
   --http \
   --execution-endpoint http://localhost:8551 \
   --execution-jwt /home/user/.local/share/erigon/jwt.hex \
   --checkpoint-sync-url "https://checkpoint.gnosischain.com"

   Here is an example of Lighthouse running the Chiado testnet:

   lighthouse bn \
   --network chiado \
   --datadir=data \
   --http \
   --execution-endpoint http://localhost:8551 \
   --execution-jwt /home/user/.local/share/erigon/jwt.hex \
   --checkpoint-sync-url "https://checkpoint.chiadochain.net"

Check the Erigon and Lighthouse logs to make sure that the EL and CL are communicating and that your node is syncing correctly.