Running Reth on OP Stack chains

reth ships with the optimism feature flag in several crates, including the binary, enabling support for OP Stack chains out of the box. Optimism has a small diff from the L1 EELS, comprising of the following key changes:

  1. A new transaction type, 0x7E (Deposit), which is used to deposit funds from L1 to L2.
  2. Modifications to the PayloadAttributes that allow the sequencer to submit transactions to the EL through the Engine API. Payloads will be built with deposit transactions at the top of the block, with the first deposit transaction always being the "L1 Info Transaction."
  3. EIP-1559 denominator and elasticity parameters have been adjusted to account for the lower block time (2s) on L2. Otherwise, the 1559 formula remains the same.
  4. Network fees are distributed to the various fee vaults.
  5. ... and some other minor changes.

For a more in-depth list of changes and their rationale, as well as specifics about the OP Stack specification such as transaction ordering and more, see the documented op-geth diff, the L2 EL specification, and the OP Stack specification.

Running on Optimism

op-reth is currently in the alpha stage of development. It is not yet ready for production use, and therefore does not have a stable release. To run it, you must build the op-reth binary from source. If you do encounter any bugs during this early stage of development, please report them in an issue on the GitHub repository.

op-reth also does not currently support OP Stack chains with legacy, pre-Bedrock state, i.e. Optimism Mainnet and Optimism Goerli. This will be possible once a database migration tool for pre-Bedrock state is released, with the capability to extract the legacy state from the old l2geth LevelDB datadir and transplant it into Reth's MDBX database.

You will need three things to run op-reth:

  1. An archival L1 node, synced to the settlement layer of the OP Stack chain you want to sync (e.g. reth, geth, besu, nethermind, etc.)
  2. A rollup node (e.g. op-node, magi, hildr, etc.)
  3. An instance of op-reth.

For this example, we'll start a Base Mainnet node.

Installing op-reth

To run Reth on Optimism, first install op-reth via the Makefile in the workspace root:

git clone git@github.com:paradigmxyz/reth.git && \
    cd reth && \
    make install-op

This will install the op-reth binary to ~/.cargo/bin/op-reth.

Installing a Rollup Node

Next, you'll need to install a Rollup Node, which is the equivalent to the Consensus Client on the OP Stack. Available options include:

  1. op-node
  2. magi
  3. hildr

For the sake of this tutorial, we'll use the reference implementation of the Rollup Node maintained by OP Labs, the op-node. The op-node can be built from source, or pulled from a Docker image available on Google Cloud.

rethdb build tag
The op-node also comes with an experimental rethdb build tag, which allows it to read receipts directly from an L1 reth database during derivation. This can speed up sync times, but it is not required if you do not have access to the L1 archive node on the same machine as your L2 node.

To build the op-node with the rethdb build tag enabled:

git clone git@github.com:ethereum-optimism/optimism.git && \
    (cd optimism/op-service/rethdb-reader && cargo build --release) && \ 
    cd optimism/op-node && \
    go build -v -tags rethdb -o ./bin/op-node ./cmd/main.go && \
    mv bin/op-node /usr/bin/op-node

This will build the rethdb-reader dylib and instruct the op-node build to statically link this dylib into the binary. The op-node binary will be installed to /usr/bin/op-node.

Running op-reth

The optimism feature flag in op-reth adds several new CLI flags to the reth binary:

  1. --rollup.sequencer-http <uri> - The sequencer endpoint to connect to. Transactions sent to the op-reth EL are also forwarded to this sequencer endpoint for inclusion, as the sequencer is the entity that builds blocks on OP Stack chains.
  2. --rollup.disable-tx-pool-gossip - Disables gossiping of transactions in the mempool to peers. This can be ommitted for personal nodes, though providers should always opt to enable this flag.
  3. --rollup.enable-genesis-walkback - Disables setting the forkchoice status to tip on startup, making the op-node walk back to genesis and verify the integrity of the chain before starting to sync. This can be ommitted unless a corruption of local chainstate is suspected.

Base's rollup.json files, which contain various configuration fields for the rollup, can be found in their node repository, under the respective L1 settlement layer's directory (mainnet, goerli, & sepolia).

First, ensure that your L1 archival node is running and synced to tip. Then, start op-reth with the --rollup.sequencer-http flag set to the Base Mainnet sequencer endpoint:

op-reth node \
    --chain base \
    --rollup.sequencer-http https://sequencer.base.org \
    --http \
    --ws \
    --authrpc.port 9551 \
    --authrpc.jwtsecret /path/to/jwt.hex

Then, once op-reth has been started, start up the op-node:

op-node \
    --l1=<your-L1-rpc> \
    --l2=http://localhost:9551 \
    --rollup.config=/path/to/rollup.json \
    --l2.jwt-secret=/path/to/jwt.hex \
    --rpc.addr=0.0.0.0 \
    --rpc.port=7000 \
    --l1.trustrpc

If you opted to build the op-node with the rethdb build tag, this "RPCKind" can be enabled via appending two extra flags to the op-node invocation:

Note, the reth_db_path is the path to the db folder inside of the reth datadir, not the mdbx.dat file itself. This can be fetched from op-reth db path [--chain <chain-name>], or if you are using a custom datadir location via the --datadir flag, by appending /db to the end of the path.

op-node \
    # ...
    --l1.rpckind=reth_db \
    --l1.rethdb=<your_L1_reth_db_path>