Aura Validator

How to setup a Nethermind Validator in Aura (Authority Round) consensus algorithm

This article will lead you through docker-compose setup of Nethermind Aura Validator (xDai chain in this example). Same result can be obtained by Downloading & Running Nethermind package or by Building Nethermind from the source code.

If you chose not to use docker-compose, you can skip docker-compose related sections and read about config file and private key configuration only.


  • docker-compose

  • docker

  • machine with at least 4GB RAM is recommended

sudo apt-get install docker docker-compose -y

Clock synchronization

You system clock needs to be synchronized otherwise you might encounter skipping block sealing. By default stepDuration is configured to 5s.

Verify if your system clock is synchronized, type timedatectl status and you should see similar output:

Local time: Tue 2020-06-30 17:16:19 UTC
Universal time: Tue 2020-06-30 17:16:19 UTC
RTC time: Tue 2020-06-30 17:16:19
Time zone: Etc/UTC (UTC, +0000)
System clock synchronized: yes
systemd-timesyncd.service active: yes
RTC in local TZ: no

If System clock synchronized displays yes you are all set, otherwise you may need to either:

  • synchronize clock with NTP servers (allow UDP port 123 for both incoming and outgoing traffic)

  • use below script to sync with

Create script and run it with watch -n 60 command in a screen

echo sudo date -s '"$(wget -qSO- --max-redirect=0 2>&1 | grep Date: | cut -d' ' -f5-8)Z"' >
chmod +x
screen -S time
watch -n 60 ./

Press Ctrl+A+D to leave the screen

Docker-compose file sample

Create and editdocker-compose.yml file

nano docker-compose.yml
version: '3.5'
image: nethermind/nethermind:alpine
container_name: nethermind-validator
restart: unless-stopped
- 8545:8545
- 30303:30303
network_mode: host
- ${PWD}/nethermind_db:/nethermind/nethermind_db
- ${PWD}/keystore:/nethermind/keystore
- ${PWD}/logs:/nethermind/logs
- ${PWD}/xdai.cfg:/nethermind/configs/xdai.cfg
- ${PWD}/NLog.config:/nethermind/NLog.config
- ${PWD}/static-nodes.json:/nethermind/Data/static-nodes.json
driver: local
name: nethermind_db
driver: local
name: keystore
driver: local
name: logs

Configure Nethermind node via environment variables or use local config file and map it to the one, existing inside container (xdai.cfg file in above example).

Make sure that nethermind_db, keystore(logs - optional ) are mapped, otherwise you might lose database or keys

NLog.config file is optional. static-nodes.json can be filled with an array of enodes, this is also optional.

Mining Private key

Make sure that the filename contains key's public address otherwise it won't be recognized by Nethermind Client as a keyfile. Correct naming of a keyfile: key-a5237f7f43cc46cba43ac212dabd0c45e3e3050a

The keyfile should be then stored inside keystore volume.

Config file

Things to be configured:

  • Init.IsMining true

  • Init.MemoryHint can be left default, recommended to configure it accordingly to the machine hardware setup (for xdai 1000000000 is enough)

  • EthStats section if you wish to report node status to the ethstats page for a given network

  • Metrics section if running local/remote Metrics infrastructure

  • KeyStore.PasswordFiles path to the file containing password for mining private key

  • KeyStore.UnlockAccounts an array of accounts, provide mining public address here

  • KeyStore.BlockAuthorAccount mining public address should be provided here as well

  • Aura.ForceSealing set to true

"Init": {
"WebSocketsEnabled": false,
"StoreReceipts": true,
"IsMining": true,
"ChainSpecPath": "chainspec/xdai.json",
"GenesisHash": "0x4f1dd23188aab3a76b463e4af801b52b1248ef073c648cbdc4c9333d3da79756",
"BaseDbPath": "nethermind_db/xdai",
"LogFileName": "xdai.logs.txt",
"MemoryHint": 3000000000,
"StaticNodesPath": "Data/static-nodes.json"
"Network": {
"DiscoveryPort": 30303,
"P2PPort": 30303
"JsonRpc": {
"Enabled": false,
"Host": "",
"Port": 8545,
"WebSocketsPort": 8546
"Db": {
"HeadersDbCacheIndexAndFilterBlocks": false,
"BlocksDbCacheIndexAndFilterBlocks": false,
"ReceiptsDbCacheIndexAndFilterBlocks": false,
"BlockInfosDbCacheIndexAndFilterBlocks": false
"Sync": {
"FastSync": true,
"PivotNumber": 10410000,
"PivotHash": "0x806f498fdde010f25bd3beb18e6f8a9c9450752f8c0e27da2cd2465ff184628c",
"PivotTotalDifficulty": "3542339439646969404653729663364707080928280566",
"FastBlocks": true,
"UseGethLimitsInFastBlocks": false,
"FastSyncCatchUpHeightDelta": 10000000000
"EthStats": {
"Enabled": false,
"Server": "ws://localhost:3000/api",
"Name": "Nethermind xDai",
"Secret": "secret",
"Contact": ""
"Metrics": {
"NodeName": "Nethermind xDai",
"Enabled": false,
"PushGatewayUrl": "http://localhost:9091/metrics",
"IntervalSeconds": 5
"KeyStore": {
"PasswordFiles": ["keystore/password.file"],
"UnlockAccounts": ["0x..."],
"BlockAuthorAccount": "0x..."
"Aura": {
"ForceSealing": true
"Bloom": {
"IndexLevelBucketSizes": [

Running Validator node

Run it with a simple docker-compose command.

docker-compose up -d

You will need to wait for the node to be fully synchronized.

To check the logs and verify if it is sealing blocks as expected (look for the Sealed block log).

docker-compose logs -f nethermind-validator