lighthouse/scripts/local_testnet

Simple Local Testnet

These scripts allow for running a small local testnet with multiple beacon nodes and validator clients and a geth execution client. This setup can be useful for testing and development.

Requirements

The scripts require lcli, lighthouse, geth, bootnode to be installed on PATH (run echo $PATH to view all PATH directories).

MacOS users need to install GNU sed and GNU grep, and add them both to PATH as well.

The first step is to install Rust and dependencies. Refer to the Lighthouse Book for installation. We will also need jq, which can be installed with sudo apt install jq.

Then, we clone the Lighthouse repository:

cd ~
git clone https://github.com/sigp/lighthouse.git
cd lighthouse

We are now ready to build Lighthouse. Run the command:

make
make install-lcli

This will build lighthouse and lcli. For geth and bootnode, go to geth website and download the Geth & Tools. For example, to download and extract Geth & Tools 1.13.1:

cd ~
curl -LO https://gethstore.blob.core.windows.net/builds/geth-alltools-linux-amd64-1.13.1-3f40e65c.tar.gz
tar xvf geth-alltools-linux-amd64-1.13.1-3f40e65c.tar.gz

After extraction, copy geth and bootnode to the PATH. A typical directory is /usr/local/bin.

cd geth-alltools-linux-amd64-1.13.1-3f40e65c
sudo cp geth bootnode /usr/local/bin

After that We can remove the downloaded files:

cd ~
rm -r geth-alltools-linux-amd64-1.13.1-3f40e65c geth-alltools-linux-amd64-1.13.1-3f40e65c.tar.gz

We are now ready to start a local testnet.

Starting the testnet

To start a testnet using the predetermined settings:

cd ~
cd ./lighthouse/scripts/local_testnet
./start_local_testnet.sh genesis.json

This will execute the script and if the testnet setup is successful, you will see "Started!" at the end.

The testnet starts with a post-merge genesis state. The testnet starts a consensus layer and execution layer boot node along with BN_COUNT (the number of beacon nodes) each connected to a geth execution client and VC_COUNT (the number of validator clients). By default, BN_COUNT=4, VC_COUNT=4.

The start_local_testnet.sh script takes four options -v VC_COUNT, -d DEBUG_LEVEL, -p to enable builder proposals and -h for help. It also takes a mandatory GENESIS_FILE for initialising geth's state. A sample genesis.json is provided in this directory.

The options may be in any order or absent in which case they take the default value specified.

• VC_COUNT: the number of validator clients to create, default: BN_COUNT
• DEBUG_LEVEL: one of { error, warn, info, debug, trace }, default: info

The ETH1_BLOCK_HASH environment variable is set to the block_hash of the genesis execution layer block which depends on the contents of genesis.json. Users of these scripts need to ensure that the ETH1_BLOCK_HASH variable is updated if genesis file is modified.

To view the beacon, validator client and geth logs:

tail -f ~/.lighthouse/local-testnet/testnet/beacon_node_1.log
tail -f ~/.lighthouse/local-testnet/testnet/validator_node_1.log
tail -f ~/.lighthouse/local-testnet/testnet/geth_1.log

where beacon_node_1 can be changed to beacon_node_2, beacon_node_3 or beacon_node_4 to view logs for different beacon nodes. The same applies to validator clients and geth nodes.

Stopping the testnet

To stop the testnet, navigate to the directory cd ~/lighthouse/scripts/local_testnet, then run the command:

./stop_local_testnet.sh

Once a testnet is stopped, it cannot be continued from where it left off. When the start local testnet command is run, it will start a new local testnet.

Manual creation of local testnet

In Starting the testnet, the testnet is started automatically with predetermined parameters (database directory, ports used etc). This section describes some modifications of the local testnet settings, e.g., changing the database directory, or changing the ports used.

The testnet also contains parameters that are specified in vars.env, such as the slot time SECONDS_PER_SLOT=3 (instead of 12 seconds on mainnet). You may change these parameters to suit your testing purposes. After that, in the local_testnet directory, run the following command to create genesis state with embedded validators and validator keys, and also to update the time in genesis.json:

./setup.sh
./setup_time.sh genesis.json

Note: The generated genesis validators are embedded into the genesis state as genesis validators and hence do not require manual deposits to activate.

Generate bootnode enr and start an EL and CL bootnode so that multiple nodes can find each other

./bootnode.sh
./el_bootnode.sh

Start a geth node:

./geth.sh <DATADIR> <NETWORK-PORT> <HTTP-PORT> <AUTH-HTTP-PORT> <GENESIS_FILE>

e.g.

./geth.sh $HOME/.lighthouse/local-testnet/geth_1 7001 6001 5001 genesis.json

Start a beacon node:

./beacon_node.sh <DATADIR> <NETWORK-PORT> <QUIC-PORT> <HTTP-PORT> <EXECUTION-ENDPOINT> <EXECUTION-JWT-PATH> <OPTIONAL-DEBUG-LEVEL>

e.g.

./beacon_node.sh $HOME/.lighthouse/local-testnet/node_1 9001 9101 8001 http://localhost:5001 ~/.lighthouse/local-testnet/geth_1/geth/jwtsecret

In a new terminal, start the validator client which will attach to the first beacon node:

./validator_client.sh <DATADIR> <BEACON-NODE-HTTP> <OPTIONAL-DEBUG-LEVEL>

e.g. to attach to the above created beacon node

./validator_client.sh $HOME/.lighthouse/local-testnet/node_1 http://localhost:8001

You can create additional geth, beacon node and validator client instances by changing the ports, e.g., for a second geth, beacon node and validator client:

./geth.sh $HOME/.lighthouse/local-testnet/geth_2 7002 6002 5002 genesis.json
./beacon_node.sh $HOME/.lighthouse/local-testnet/node_2 9002 9102 8002 http://localhost:5002 ~/.lighthouse/local-testnet/geth_2/geth/jwtsecret
./validator_client.sh $HOME/.lighthouse/local-testnet/node_2 http://localhost:8002

Additional Info

Adjusting number and distribution of validators

The VALIDATOR_COUNT parameter is used to specify the number of insecure validator keystores to generate and make deposits for. The BN_COUNT parameter is used to adjust the division of these generated keys among separate validator client instances. For e.g. for VALIDATOR_COUNT=80 and BN_COUNT=4, the validator keys are distributed over 4 datadirs with 20 keystores per datadir. The datadirs are located in $DATADIR/node_{i} which can be passed to separate validator client instances using the --datadir parameter.

Starting fresh

You can delete the current testnet and all related files using the following command. Alternatively, if you wish to start another testnet, doing the steps Starting the testnet will automatically delete the files and start a fresh local testnet.

./clean.sh

Updating the genesis time of the beacon state

If it's been a while since you ran ./setup then the genesis time of the genesis state will be far in the future, causing lots of skip slots.

Update the genesis time to now using:

./reset_genesis_time.sh

Note: you probably want to just rerun ./start_local_testnet.sh to start over but this is another option.

Testing builder flow

1. Add builder URL to BN_ARGS in ./vars.env, e.g. --builder http://localhost:8650. Some mock builder server options:
   • mock-relay
   • dummy-builder
2. The above mock builders do not support non-mainnet presets as of now, and will require setting SECONDS_PER_SLOT and SECONDS_PER_ETH1_BLOCK to 12 in ./vars.env.
3. Start the testnet with the following command (the -p flag enables the validator client --builder-proposals flag):

   ./start_local_testnet.sh -p genesis.json
   

4. Block production using builder flow will start at epoch 4.

Testing sending a transaction

Some addresses in the local testnet are seeded with testnet ETH, allowing users to carry out transactions. To send a transaction, we first add the address to a wallet, such as Metamask. The private keys for the addresses are listed here.

Next, we add the local testnet to Metamask, a brief guide can be found here. If you start the local testnet with default settings, the network RPC is: http://localhost:6001 and the Chain ID is 4242, as defined in vars.env. Once the network and account are added, you should see that the account contains testnet ETH which allow us to carry out transactions.