Casper is the blockchain platform purpose-built to scale opportunity for everyone. Building toward blockchain’s next frontier, Casper is designed for real-world applications without sacrificing usability, cost, decentralization, or security. It removes the barriers that prevent mainstream blockchain adoption by making blockchain friendly to use, open to the world, and future-proof to support innovations today and tomorrow. Guided by open-source principles and built from the ground up to empower individuals, the team seeks to provide an equitable foundation made for long-lasting impact. Read more about our mission at: https://casperlabs.io/company

Current Development Status

The status on development is reported during the Community calls and is found here

The Casper Testnet is live.

• Transactions can be sent to: deploy.casperlabs.io via the client or via Clarity.
• Clarity Block Exporer

Specification

• Platform Specification
• Highway Consensus Proofs

Get Started with Smart Contracts

• Writing Smart Contracts
• Rust Smart Contract SDK
• Rust Smart Contract API Docs
• AssemblyScript Smart Contract API

Community

• Discord Server
• CasperLabs Community Forum
• Telegram Channel

casper-node

This is the core application for the Casper blockchain.

Running a validator node from Source

Pre-Requisites for Building

• CMake 3.1.4 or greater
• Rust
• libssl-dev
• pkg-config
• gcc
• g++
• optionally wasm-strip (used to reduce the size of compiled Wasm)

Setup

Before building a node, prepare your Rust build environment, and build the required system smart contracts:

make setup-rs
make build-system-contracts -j

The node software can be compiled afterwards:

cargo build -p casper-node --release

The result will be a casper-node binary found in target/release. Copy this somewhere into your PATH, or substitute target/release/casper-node for casper-node in all examples below.

Running one node

To run a validator node you will need to specify a config file and launch the validator subcommand, for example

casper-node validator /etc/casper-node/config.toml

The node ships with an example configuration file that should be setup first. There is also a template for a local chainspec in the same folder.

For launching, the following configuration values must be properly set:

Setting

Description

network.known_addresses

Must refer to public listening addresses of one or more currently-running nodes. If the node cannot connect to any of these addresses, it will panic. The node can be run with this referring to its own address, but it will be equivalent to specifying an empty list for known_addresses - i.e. the node will run and listen, but will be reliant on other nodes connecting to it in order to join the network. This would be normal for the very first node of a network, but all subsequent nodes should normally specify that first node's public listening address as their known_addresses.

Running multiple nodes on one machine

If you want to run multiple instances on the same machine, you will need to modify the following configuration values:

Setting	Description
consensus.secret_key_path	The path to the secret key must be different for each node, as no two nodes should be using an identical secret key.
storage.path	Storage must be separate for each node, e.g. /tmp/node-2-storage for the second node
network.bind_address	Each node requires a different bind address, although the port can be set to 0, which will cause the node to select a random port.
network.gossip_interval	(optional) To reduce the initial time to become fully interconnected, this value can be reduced, e.g. set to 1000 for once every second. However, beware thatthis will also increase the network traffic, as gossip rounds between the nodes will continue to be exchanged at this frequency for the duration of the network.

The nodes can take quite a long time to become fully interconnected. This is dependent on the network.gossip_interval value (in milliseconds). Nodes gossip their own listening addresses at this frequency.

There is a tool which automates the process of running multiple nodes on a single machine.

Note that running multiple nodes on a single machine is normally only recommended for test purposes.

Configuration

In general nodes are configured through a configuration file, typically named config.toml. This file may reference other files or locations through relative paths. When it does, note that all paths that are not absolute will be resolved relative to config.toml directory.

CLI overrides

It is possible to override config file options from the command line using one or more args in the form of -C=<SECTION>.<KEY>=<VALUE>. These will override values set in a config file if provided, or will override the default values otherwise. For example

casper-node validator /etc/casper-node/config.toml \
    -C=consensus.secret_key_path=secret_keys/node-1.pem \
    -C=network.known_addresses="[1.2.3.4:34553, 200.201.203.204:34553]"

will override the consensus.secret_key_path and the network.known_addresses configuration setting.

Be aware that semicolons are prohibited (even escaped) from being used in any option passed on the command line.

Environment overrides

Some environments may call for overriding options through the environment rather than the command line. In this scenario, the NODE_CONFIG environment variable can be used. For example, the command from the previous section can be alternatively expressed as

export NODE_CONFIG=consensus.secret_key_path=secret_keys/node-1.pem;network.known_addresses=[1.2.3.4:34553, 200.201.203.204:34553]
casper-node validator /etc/casper-node/config.toml

Note how the semicolon is used to separate configuration overrides here.

Development environment variables

To set the threshold at which a warn-level log message is generated for a long-running reactor event, use the env var CL_EVENT_MAX_MICROSECS. For example, to set the threshold to 1 millisecond:

CL_EVENT_MAX_MICROSECS=1000

Logging

Logging can be enabled by setting the environment variable RUST_LOG. This can be set to one of the following levels, from lowest priority to highest: trace, debug, info, warn, error:

RUST_LOG=info cargo run --release -- validator resources/local/config.toml

If the environment variable is unset, it is equivalent to setting RUST_LOG=error.

Log message format

A typical log message will look like:

Jun 09 01:40:17.315 INFO  [casper_node::components::rpc_server rpc_server.rs:127] starting HTTP server; server_addr=127.0.0.1:7777

This is comprised of the following parts:

• timestamp
• log level
• full module path (not to be confused with filesystem path) of the source of the message
• filename and line number of the source of the message
• message

Filtering log messages

RUST_LOG can be set to enable varying levels for different modules. Simply set it to a comma-separated list of module-path=level, where the module path is as shown above in the typical log message, with the end truncated to suit.

For example, to enable trace level logging for the small_network module in components, info level for all other modules in components, and warn level for the remaining codebase:

RUST_LOG=casper_node::components::small=trace,casper_node::comp=info,warn

Debugging

Some additional debug functionality is available, mainly allowed for inspections of the internal event queue.

Event queue dump

The event queue can be dumped by sending a SIGUSR1 to the running node process, e.g. if the node's process ID was $NODE_PID:

kill -USR1 $NODE_PID

This will create a queue_dump.json in the working directory of the node. A tool like jq can then be used to format and display it:

$ jq < queue_dump.json
{
  "NetworkIncoming": [],
  "Network": [],
  "Regular": [
    "AddressGossiper"
  ],
  "Api": []
}

jq Examples

Dump the type of events:

jq 'map_values( map(keys[0] | {"type": ., weight: 1})| group_by(.type) | map ([.[0].type,(.|length)]) | map({(.[0]): .[1]}) )' queue_dump.json

Count number of events in each queue:

jq 'map_values(map(keys[0]))' queue_dump.json

Running a client

See the client README.

Running a local network

See the nctl utility README.