Configuring Juno ⚙
Juno can be configured using several methods, with the following order of precedence:
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
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
Environment variables rank second in configuration precedence. Command line parameters override environment variables.
Configuration file
Juno can be configured using a 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>
By default, Juno looks for the configuration file in the $XDG_CONFIG_HOME directory.
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 Option | Default Value | Description |
|---|---|---|
cn-core-contract-address | Custom network core contract address | |
cn-feeder-url | Custom network feeder URL | |
cn-gateway-url | Custom network gateway URL | |
cn-l1-chain-id | Custom network L1 chain id | |
cn-l2-chain-id | Custom network L2 chain id | |
cn-name | Custom network name | |
cn-unverifiable-range | [] | Custom network range of blocks to skip hash verifications (e.g. 0,100) |
colour | true | Use --colour=false command to disable colourized outputs (ANSI Escape Codes) |
config | The YAML configuration file | |
db-cache-size | 8 | Determines the amount of memory (in megabytes) allocated for caching data in the database |
db-max-handles | 1024 | A soft limit on the number of open files that can be used by the DB |
db-path | juno | Location of the database files |
eth-node | WebSocket 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 | |
grpc | false | Enable the HTTP gRPC server on the default port |
grpc-host | localhost | The interface on which the gRPC server will listen for requests |
grpc-port | 6064 | The port on which the gRPC server will listen for requests |
gw-api-key | API key for gateway endpoints to avoid throttling | |
gw-timeout | 5 | Timeout for requests made to the gateway |
http | false | Enables the HTTP RPC server on the default port and interface |
http-host | localhost | The interface on which the HTTP RPC server will listen for requests |
http-port | 6060 | The port on which the HTTP server will listen for requests |
log-level | info | Options: trace, debug, info, warn, error |
max-vm-queue | 2 * max-vms | Maximum number for requests to queue after reaching max-vms before starting to reject incoming requests |
max-vms | 3 * CPU Cores | Maximum number for VM instances to be used for RPC calls concurrently |
metrics | false | Enables the Prometheus metrics endpoint on the default port |
metrics-host | localhost | The interface on which the Prometheus endpoint will listen for requests |
metrics-port | 9090 | The port on which the Prometheus endpoint will listen for requests |
network | mainnet | Options: mainnet, sepolia, sepolia-integration |
p2p | false | EXPERIMENTAL: Enables p2p server |
p2p-addr | EXPERIMENTAL: Specify p2p source address as multiaddr | |
p2p-feeder-node | false | EXPERIMENTAL: Run juno as a feeder node which will only sync from feeder gateway and gossip the new blocks to the network |
p2p-peers | EXPERIMENTAL: Specify list of p2p peers split by a comma. These peers can be either Feeder or regular nodes | |
p2p-private-key | EXPERIMENTAL: Hexadecimal representation of a private key on the Ed25519 elliptic curve | |
pending-poll-interval | 5 | Sets how frequently pending block will be updated (0s will disable fetching of pending block) |
pprof | false | Enables the pprof endpoint on the default port |
pprof-host | localhost | The interface on which the pprof HTTP server will listen for requests |
pprof-port | 6062 | The port on which the pprof HTTP server will listen for requests |
remote-db | gRPC URL of a remote Juno node | |
rpc-call-max-steps | 4000000 | Maximum 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-enable | false | Enable CORS on RPC endpoints |
rpc-max-block-scan | 18446744073709551615 | Maximum number of blocks scanned in single starknet_getEvents call |
ws | false | Enables the WebSocket RPC server on the default port |
ws-host | localhost | The interface on which the WebSocket RPC server will listen for requests |
ws-port | 6061 | The port on which the WebSocket server will listen for requests |