Running OP Testnet from Source

Before You Begin

You need to know some prerequisite information on migrated vs. non-migrated networks shared in this section.

• Migrated Networks, OP Mainnet and OP Goerli, were running before the Bedrock upgrade.
• Non-Migrated Networks, OP Sepolia, have only existed in a post Bedrock world. The way transaction execution is handled is fundamentally different pre- vs post-bedrock.
• Migrated networks are required to initialize their nodes with a data directory and non-migrated networks can simply initialize from a genesis file.

OP Sepolia Initialization

OP Sepolia is non-migrated network so it requires initialization via genesis file. op-geth uses JSON files to encode a network's genesis information. You'll need to download the genesis JSON, then run the following command to initialize the data directory:

curl -o <path to genesis JSON> -sL https://networks.optimism.io/op-sepolia/genesis.json
 
geth init \
	 --datadir="<your data directory>" \
	 "<path to genesis JSON>"

Create a shared secret between op-geth and op-node

openssl rand -hex 32 > jwt.txt

Start op-geth

./build/bin/geth \
  --datadir=<</path/to/op-geth-datadir>> \
  --http \
  --http.port=8545 \
  --http.addr=0.0.0.0 \
  --authrpc.addr=localhost \
  --authrpc.jwtsecret=./jwt.txt \
  --verbosity=3 \
  --rollup.sequencerhttp=https://sepolia-sequencer.optimism.io/ \
  --nodiscover \
  --syncmode=full \
  --maxpeers=0 \
  --op-network=op-sepolia

Start op-node

./bin/op-node \
    --l1=<< L1 RPC URL >>  \
    --l1.rpckind=<< L1 RPC KIND >> \
    --l2=ws://localhost:8551 \
    --l2.jwt-secret=<< /path/to/op-geth/jwt.txt >> \
    --rpc.addr=0.0.0.0 \
    --rpc.port=8547 \
    --network=op-sepolia \
    --rollup.load-protocol-versions=true

The initial synchronization

The datadir provided by Optimism is not updated continuously, so before you can use the node you need a to synchronize it.

During that process you get log messages from op-node, and nothing else appears to happen.

INFO [06-26|13:31:20.389] Advancing bq origin                      origin=17171d..1bc69b:8300332 originBehind=false

That is normal - it means that op-node is looking for a location in the batch queue. After a few minutes it finds it, and then it can start synchronizing.

While it is synchronizing, you can expect log messages such as these from op-node:

INFO [06-26|14:00:59.460] Sync progress                            reason="processed safe block derived from L1" l2_finalized=ef93e6..e0f367:4067805 l2_safe=7fe3f6..900127:4068014 l2_unsafe=7fe3f6..900127:4068014 l2_time=1,673,564,096 l1_derived=6079cd..be4231:8301091
INFO [06-26|14:00:59.460] Found next batch                         epoch=8e8a03..11a6de:8301087 batch_epoch=8301087 batch_timestamp=1,673,564,098
INFO [06-26|14:00:59.461] generated attributes in payload queue    txs=1  timestamp=1,673,564,098
INFO [06-26|14:00:59.463] inserted block                           hash=e80dc4..72a759 number=4,068,015 state_root=660ced..043025 timestamp=1,673,564,098 parent=7fe3f6..900127 prev_randao=78e43d..36f07a fee_recipient=0x4200000000000000000000000000000000000011 txs=1  update_safe=true

And log messages such as these from op-geth:

INFO [06-26|14:02:12.974] Imported new potential chain segment     number=4,068,194 hash=a334a0..609a83 blocks=1         txs=1         mgas=0.000  elapsed=1.482ms     mgasps=0.000   age=5mo2w20h dirty=2.31MiB
INFO [06-26|14:02:12.976] Chain head was updated                   number=4,068,194 hash=a334a0..609a83 root=e80f5e..dd06f9 elapsed="188.373µs" age=5mo2w20h
INFO [06-26|14:02:12.982] Starting work on payload                 id=0x5542117d680dbd4e

Estimate the synchronization time

To estimate how long the synchronization will take, you need to first find out how many blocks you synchronize in a minute. You can use this Foundry (opens in a new tab) script to get an estimated sync time.

touch run-estimate.sh

chmod +x run-estimate.sh

#!/usr/bin/bash
 
export ETH_RPC_URL=http://localhost:8545
CHAIN_ID=`cast chain-id`
echo Chain ID: $CHAIN_ID
echo Please wait
 
if [ $CHAIN_ID -eq 10 ]; then
  L2_URL=https://mainnet.optimism.io
fi
 
 
if [ $CHAIN_ID -eq 420 ]; then
  L2_URL=https://goerli.optimism.io
fi
 
 
if [ $CHAIN_ID -eq 11155420 ]; then
  L2_URL=https://sepolia.optimism.io
fi
 
T0=`cast block-number --rpc-url $ETH_RPC_URL` ; sleep 60 ; T1=`cast block-number --rpc-url $ETH_RPC_URL`
PER_MIN=`expr $T1 - $T0`
echo Blocks per minute: $PER_MIN
 
 
if [ $PER_MIN -eq 0 ]; then
    echo Not synching
    exit;
fi
 
# During that minute the head of the chain progressed by thirty blocks
PROGRESS_PER_MIN=`expr $PER_MIN - 30`
echo Progress per minute: $PROGRESS_PER_MIN
 
 
# How many more blocks do we need?
HEAD=`cast block-number --rpc-url $L2_URL`
BEHIND=`expr $HEAD - $T1`
MINUTES=`expr $BEHIND / $PROGRESS_PER_MIN`
HOURS=`expr $MINUTES / 60`
echo Hours until sync completed: $HOURS
 
if [ $HOURS -gt 24 ] ; then
   DAYS=`expr $HOURS / 24`
   echo Days until sync complete: $DAYS
fi

./run-estimate.sh

Operations

It is best to start op-geth first and shut it down last.

Next Steps

• Now that you've got your node up and running, check out the Node Metrics and Monitoring Guide for health monitoring.
• If you run into any problems, please visit the Node Troubleshooting Guide for help.