Espresso

Decaf Testnet

Espresso is a high-performance base layer for rollups, making L2 transactions safe, fast, and seamless for users. Espresso is trusted by leading teams including Offchain Labs (Arbitrum), Polygon, ApeChain, Cartesi, RARI Chain, Celo.

L2s and rollups that use Espresso as a decentralized base layer benefit from industry-leading speed in finalizing transactions. The confirmations that Espresso provides underpin cross-chain applications that can tap into liquidity and users of all connected Espresso-chains. Resources

Website	https://www.espressosys.com/
Github	https://github.com/EspressoSystems
Explorer	https://explorer.decaf.testnet.espresso.network/nodes
Docs	https://docs.espressosys.com/network
Discord	https://discord.com/invite/YHZPk5dbcq

Hardware requirements

CPU

4 cores

RAM

16 GB

Storage

1 TGB NVME

Network

25 MBit/s

OS

Linux (Ubuntu 22.04 x64)

Installation 💾

Update repositories

apt update && apt upgrade -y

Install dependencies

sudo apt install -y curl jq ca-certificates gnupg lsb-release openssl

Install Docker

sudo install -m 0755 -d /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
sudo chmod a+r /etc/apt/keyrings/docker.gpg

echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" \
| sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

sudo apt-get update
sudo apt-get install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin
sudo systemctl enable --now docker

Create folders

mkdir -p $HOME/Espresso-test
cd ~/Espresso-test
mkdir -p sepolia/geth sepolia/lighthouse sepolia/jwt keys espresso-store

Create .env for your node identity + public IP

nano ~/Espresso-test/.env

PUBLIC_IP=YOUR_PUBLIC_IP
NODE_NAME=your-espresso-validator-01
COMPANY_NAME=YourCompany
COMPANY_WEBSITE=https://example.com
NETWORK_TYPE=Hosted
COUNTRY_CODE=US

SEPOLIA_CHECKPOINT_URL=https://beaconstate-sepolia.chainsafe.io

Create docker-compose.yml (Sepolia EL+CL + Espresso Decaf)

nano ~/Espresso-test/docker-compose.yml

services:
  geth-sepolia:
    image: ethereum/client-go:stable
    restart: unless-stopped
    command: >
      --sepolia
      --datadir=/data
      --syncmode=snap
      --http --http.addr=0.0.0.0 --http.port=8545 --http.vhosts=* --http.corsdomain=*
      --http.api=eth,net,web3,txpool
      --ws --ws.addr=0.0.0.0 --ws.port=8546 --ws.origins=*
      --ws.api=eth,net,web3,txpool
      --authrpc.addr=0.0.0.0 --authrpc.port=8551 --authrpc.vhosts=* --authrpc.jwtsecret=/jwt/jwt.hex
      --port=30303
      --nat=any
    volumes:
      - ./sepolia/geth:/data
      - ./sepolia/jwt:/jwt
    ports:
      - "18545:8545/tcp"
      - "18546:8546/tcp"
      - "18551:8551/tcp"
      - "40303:30303/tcp"
      - "40303:30303/udp"

  lighthouse-sepolia:
    image: sigp/lighthouse:v8.0.0
    restart: unless-stopped
    depends_on:
      - geth-sepolia
    command: >
      lighthouse beacon_node
      --network sepolia
      --datadir /data
      --execution-endpoint http://geth-sepolia:8551
      --execution-jwt /jwt/jwt.hex
      --checkpoint-sync-url ${SEPOLIA_CHECKPOINT_URL}
      --checkpoint-sync-url-timeout 300
      --http --http-address 0.0.0.0 --http-port 5052
      --metrics --metrics-address 0.0.0.0 --metrics-port 5054
      --port 9000
      --discovery-port 9000
    volumes:
      - ./sepolia/lighthouse:/data
      - ./sepolia/jwt:/jwt:ro
    ports:
      - "15052:5052/tcp"
      - "15054:5054/tcp"
      - "49000:9000/tcp"
      - "49000:9000/udp"

  espresso-decaf:
    image: ghcr.io/espressosystems/espresso-sequencer/sequencer:20251120
    restart: unless-stopped
    depends_on:
      - geth-sepolia
      - lighthouse-sepolia
    environment:
      ESPRESSO_SEQUENCER_API_PORT: "8080"
      ESPRESSO_SEQUENCER_GENESIS_FILE: "/genesis/decaf.toml"
      ESPRESSO_SEQUENCER_KEY_FILE: "/mount/sequencer/keys/0.env"
      ESPRESSO_SEQUENCER_STORAGE_PATH: "/mount/sequencer/store"

      ESPRESSO_SEQUENCER_CONFIG_PEERS: "https://cache.decaf.testnet.espresso.network"
      ESPRESSO_SEQUENCER_ORCHESTRATOR_URL: "https://orchestrator-UZAFTUIMZOT.decaf.testnet.espresso.network/"
      ESPRESSO_SEQUENCER_CDN_ENDPOINT: "cdn.decaf.testnet.espresso.network:1737"
      ESPRESSO_STATE_RELAY_SERVER_URL: "https://state-relay.decaf.testnet.espresso.network"
      ESPRESSO_SEQUENCER_STATE_PEERS: "https://query.decaf.testnet.espresso.network"

      ESPRESSO_SEQUENCER_L1_PROVIDER: "http://geth-sepolia:8545"
      ESPRESSO_SEQUENCER_L1_WS_PROVIDER: "ws://geth-sepolia:8546"

      ESPRESSO_SEQUENCER_LIBP2P_BIND_ADDRESS: "0.0.0.0:9000"
      ESPRESSO_SEQUENCER_LIBP2P_ADVERTISE_ADDRESS: "${PUBLIC_IP}:19000"

      ESPRESSO_SEQUENCER_IDENTITY_NODE_NAME: "${NODE_NAME}"
      ESPRESSO_SEQUENCER_IDENTITY_COMPANY_NAME: "${COMPANY_NAME}"
      ESPRESSO_SEQUENCER_IDENTITY_COMPANY_WEBSITE: "${COMPANY_WEBSITE}"
      ESPRESSO_SEQUENCER_IDENTITY_NETWORK_TYPE: "${NETWORK_TYPE}"
      ESPRESSO_SEQUENCER_IDENTITY_COUNTRY_CODE: "${COUNTRY_CODE}"

      RUST_LOG: "warn,hotshot_libp2p_networking=off"
      RUST_LOG_FORMAT: "json"
    volumes:
      - ./keys:/mount/sequencer/keys
      - ./espresso-store:/mount/sequencer/store
    ports:
      - "18080:8080/tcp"
      - "19000:9000/tcp"
      - "19000:9000/udp"

start

cd ~/Espresso-test/ && docker compose up -d

docker compose ps

Become Validator

You may need approval / tokens from Espresso

Decaf docs note node operation is limited to a select group and provide a form to request tokens.

Register your validator on Sepolia (staking-cli)

Decaf registration uses staking-cli register-validator and requires:

• your validator Ethereum address (the address you register)

• a commission value (decimal between 0 and 1)

• Sepolia RPC URL (your own is http://127.0.0.1:18545)

Decaf contract addresses from docs (set these exactly as environment variables when using staking-cli):

export STAKING_CONTRACT_ADDRESS=0x40304fbe94d5e7d1492dd90c53a2d63e8506a037
export ESP_TOKEN_CONTRACT_ADDRESS=0x4d4a35a5c843461cdf5f889045d69c59dd18be18

Example:

staking-cli register-validator \
  --validator-address 0xYOUR_VALIDATOR_ADDRESS \
  --commission 0.05 \
  --rpc-url http://127.0.0.1:18545

If you got --commission ... empty: it usually means your shell variable was empty (e.g. --commission $COMMISSION but COMMISSION wasn’t set). Use a literal number like 0.05.

Delegation (required to actually participate)

Decaf uses a dynamic active set (top 100 by delegation) and you need ESP tokens delegated to your validator to be active.

Example:

staking-cli delegate \
  --validator-address 0xYOUR_VALIDATOR_ADDRESS \
  --amount YOUR_AMOUNT_IN_ESP \
  --rpc-url http://127.0.0.1:18545

Validator address clarification: it’s the address you used in register-validator (and that will receive commission/rewards), not “whatever address has Sepolia ETH”. Sepolia ETH is just gas to send the registration/delegation transactions.

Cheat sheet (status, logs, quick health checks)

Logs (use your container names)

docker logs --tail=100 espresso-test-geth-sepolia-1
docker logs --tail=100 espresso-test-lighthouse-sepolia-1
docker logs --tail=100 espresso-test-espresso-decaf-1

Follow live:

docker logs -f espresso-test-espresso-decaf-1

Sepolia EL sync (geth)

curl -s -X POST http://127.0.0.1:18545 \
  -H 'content-type: application/json' \
  --data '{"jsonrpc":"2.0","id":1,"method":"eth_syncing","params":[]}' | jq

Sepolia CL health (lighthouse HTTP API)

curl -sS -i http://127.0.0.1:15052/eth/v1/node/health

Espresso metrics (best single check)

curl -sSL http://127.0.0.1:18080/v1/status/metrics \
 | egrep -i 'consensus_libp2p_num_connected_peers|consensus_libp2p_is_ready|consensus_current_view|consensus_last_decided_view' \
 | head -50

Interpretation (rule of thumb):

• consensus_libp2p_is_ready 1

• consensus_libp2p_num_connected_peers > 0 (ideally dozens)

• consensus_current_view keeps increasing

• consensus_last_decided_view stays close to current_view

Restart only Espresso (safe)

docker compose restart espresso-decaf