@typeberry/jam

Command-line interface for running a Typeberry JAM node.

Usage

jam [options]
jam [options] dev <dev-validator-index>
jam [options] import <bin-or-json-blocks>
jam [options] export <output-directory-or-file>
jam [options] [--version=1] fuzz-target [socket-path=/tmp/jam_target.sock]
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Commands

jam (default)

Run a JAM node in regular operation mode.

jam --name=my-node --config=default
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jam dev <index>

Run a JAM node in development mode as a validator. The <index> parameter determines the validator slot and automatically configures:

• Node name (e.g., jam-1, jam-2)
• Networking port (12346, 12347, etc.)
• Local bootnodes for a 5-validator dev network
• Block authoring capabilities

# Start first dev validator
jam dev 1

# Start second dev validator
jam dev 2
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jam import <files...>

Import blocks from one or more .bin or .json files into the node's database. The node will start, import the blocks, and then exit.

jam import blocks/block-1.bin blocks/block-2.bin
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jam export <output>

Export blocks from the node's database to the specified output directory or file.

jam export ./exported-blocks
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jam fuzz-target [socket]

Run the node as a fuzzing target, listening on the specified Unix socket path (defaults to /tmp/jam_target.sock).

jam --version=1 fuzz-target /tmp/custom_socket.sock
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Options

--name

Override the node name. This affects the networking key derivation and database location.

Default: jam

jam --name=alice
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--config

Configuration directives for the node. Can be specified multiple times and are evaluated left to right.

A configuration directive can be:

• A path to a config file
• An inline JSON object
• A pseudo-jq query (subset of jq syntax for modifying config)
• One of the predefined configs: dev, default

Default: default

Examples:

# Use dev configuration
jam --config=dev

# Modify bootnodes in dev config (merge)
jam --config=dev --config=.chain_spec+={"bootnodes": []}

# Replace entire chain spec property
jam --config=dev --config=.chain_spec={"bootnodes": []}

# Merge JSON file onto chain spec
jam --config=dev --config=.chain_spec+=bootnodes.json

# Merge JSON object onto dev config
jam --config=dev --config={"chain_spec": {"bootnodes": []}}

# Merge contents of JSON file onto dev config
jam --config=dev --config=bootnodes.json

# Use custom config file
jam --config=custom-config.json
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--pvm

Select the PVM (Polkavm) backend to use. Available options: wasmtime, interpreter, ananas.

Default: ananas

jam --pvm=wasmtime
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Environment Variables

JAM_LOG

Control logging output. Set to a comma-separated list of log filters.

JAM_LOG=trace jam dev 1
JAM_LOG=networking:debug,state:trace jam
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Development

The dev command is designed for local testing with multiple validators:

# Terminal 1
jam dev 1

# Terminal 2
jam dev 2

# Terminal 3
jam dev 3
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Each validator automatically discovers the others via local bootnodes and begins block production.