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Version: 0.11.8

Configuring Juno

Juno can be configured using several methods, with the following order of precedence:

  1. Command line parameters (flags)
  2. Environment variables
  3. Configuration file

Command line params

Juno can be configured directly on the command line by prefixing -- to each option name:

./build/juno --http --http-port 6060 --http-host 0.0.0.0

When using Docker, append the command line parameters after the image name to configure Juno:

docker run nethermind/juno --http --http-port 6060 --http-host 0.0.0.0
tip

Command line parameters override environment variables and configuration file.

Environment variables

Juno can be configured through environment variables by prefixing the variable names with JUNO_ and using the configuration options in SCREAMING_SNAKE_CASE format.

To set the http, http-port, and http-host configurations, Juno should be run in this format:

JUNO_HTTP=true JUNO_HTTP_PORT=6060 JUNO_HTTP_HOST=0.0.0.0 ./build/juno

When using Docker, start Juno using the -e command option:

docker run \
-e "JUNO_HTTP=true JUNO_HTTP_PORT=6060 JUNO_HTTP_HOST=0.0.0.0" \
nethermind/juno
tip

Environment variables rank second in configuration precedence. Command line parameters override environment variables.

Configuration file

Juno can be configured using a YAML file:

Sample YAML File
log-level: info
network: mainnet
http: true
http-port: 6060
metrics: true
metrics-port: 9090

To run Juno with a configuration file, use the config option to specify the path of the configuration file:

# Standalone binary
./build/juno --config <CONFIG FILE PATH>

# Docker container
docker run nethermind/juno --config <CONFIG FILE PATH>
info

By default, Juno looks for the configuration file in the $XDG_CONFIG_HOME directory.

tip

Configuration file rank third in configuration precedence. Command line parameters and environment variables override configuration file.

Configuration options

To list all available command line options, you can use the --help parameter:

# Standalone binary
./build/juno --help

# Docker container
docker run nethermind/juno --help

Below is a list of all configuration options available in Juno, along with their default values and descriptions:

Config OptionDefault ValueDescription
cn-core-contract-addressCustom network core contract address
cn-feeder-urlCustom network feeder URL
cn-gateway-urlCustom network gateway URL
cn-l1-chain-idCustom network L1 chain id
cn-l2-chain-idCustom network L2 chain id
cn-nameCustom network name
cn-unverifiable-range[]Custom network range of blocks to skip hash verifications (e.g. 0,100)
colourtrueUse --colour=false command to disable colourized outputs (ANSI Escape Codes)
configThe YAML configuration file
db-cache-size8Determines the amount of memory (in megabytes) allocated for caching data in the database
db-max-handles1024A soft limit on the number of open files that can be used by the DB
db-pathjunoLocation of the database files
eth-nodeWebSocket endpoint of the Ethereum node. To verify the correctness of the L2 chain, Juno must connect to an Ethereum node and parse events in the Starknet contract
grpcfalseEnable the HTTP gRPC server on the default port
grpc-hostlocalhostThe interface on which the gRPC server will listen for requests
grpc-port6064The port on which the gRPC server will listen for requests
gw-api-keyAPI key for gateway endpoints to avoid throttling
gw-timeout5Timeout for requests made to the gateway
httpfalseEnables the HTTP RPC server on the default port and interface
http-hostlocalhostThe interface on which the HTTP RPC server will listen for requests
http-port6060The port on which the HTTP server will listen for requests
log-levelinfoOptions: trace, debug, info, warn, error
max-vm-queue2 * max-vmsMaximum number for requests to queue after reaching max-vms before starting to reject incoming requests
max-vms3 * CPU CoresMaximum number for VM instances to be used for RPC calls concurrently
metricsfalseEnables the Prometheus metrics endpoint on the default port
metrics-hostlocalhostThe interface on which the Prometheus endpoint will listen for requests
metrics-port9090The port on which the Prometheus endpoint will listen for requests
networkmainnetOptions: mainnet, sepolia, sepolia-integration
p2pfalseEXPERIMENTAL: Enables p2p server
p2p-addrEXPERIMENTAL: Specify p2p source address as multiaddr
p2p-feeder-nodefalseEXPERIMENTAL: Run juno as a feeder node which will only sync from feeder gateway and gossip the new blocks to the network
p2p-peersEXPERIMENTAL: Specify list of p2p peers split by a comma. These peers can be either Feeder or regular nodes
p2p-private-keyEXPERIMENTAL: Hexadecimal representation of a private key on the Ed25519 elliptic curve
pending-poll-interval5Sets how frequently pending block will be updated (0s will disable fetching of pending block)
pproffalseEnables the pprof endpoint on the default port
pprof-hostlocalhostThe interface on which the pprof HTTP server will listen for requests
pprof-port6062The port on which the pprof HTTP server will listen for requests
remote-dbgRPC URL of a remote Juno node
rpc-call-max-steps4000000Maximum number of steps to be executed in starknet_call requests. The upper limit is 4 million steps, and any higher value will still be capped at 4 million
rpc-cors-enablefalseEnable CORS on RPC endpoints
rpc-max-block-scan18446744073709551615Maximum number of blocks scanned in single starknet_getEvents call
wsfalseEnables the WebSocket RPC server on the default port
ws-hostlocalhostThe interface on which the WebSocket RPC server will listen for requests
ws-port6061The port on which the WebSocket server will listen for requests