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Basic Node Configuration

This page outlines the processes and files involved in setting up a Casper node. For step-by-step node installation instructions, follow the Node Setup guide.

The Casper Node Launcher​

A node is usually run by executing the casper-node-launcher, which executes the casper-node as a child process and also handles upgrades to bring the node to the latest version released.

The casper-node-launcher can be installed via a Debian package, which also creates the casper user and directory structures and sets up a systemd unit and logging.

The casper-node-launcher Debian package can be obtained from https://repo.casperlabs.io. You only need to run the steps detailed there once.

Then, proceed to install the casper-node-launcher by running these commands:

sudo apt update
sudo apt install casper-node-launcher

You can also build from source. However, all the setup and pull of casper-node releases will be manual.

File Locations​

The casper-node-launcher Debian installation creates the directories and files needed to run casper-node versions and perform upgrades. A casper user and casper group are created during installation and used to run the software. Two main folders are relevant for our software: /etc/casper and /var/lib/casper.

The casper-node install version

Each version of the casper-node install is located based on the semantic version with underscores. For example, version 1.0.3 is represented by a directory named 1_0_3. This convention applies to both binary and configuration file locations. Versioning with [m_n_p] represents the major, minor, and patch of a semantic version.

note

Multiple versioned folders will exist on a system when upgrades are set up.

The following is the filesystem's state after installing the casper-client and casper-node-launcher Debian packages, and after running the command sudo -u casper /etc/casper/node_util.py stage_protocols casper.conf (Use casper-test.conf if on Testnet).

/usr/bin/​

The default location for executables from the Debian package install is /usr/bin.

  • casper-client - A client for interacting with a Casper network
  • casper-node-launcher - The launcher application which starts the casper-node as a child process

/etc/casper/​

This is the default location for configuration files. It can be overwritten with the CASPER_CONFIG_DIR environment variable. The paths in this document assume the default configuration file location of /etc/casper. The data is organized as follows:

  • delete_local_db.sh - Removes *.lmdb* files from /var/lib/casper/casper-node
  • pull_casper_node_version.sh - Pulls bin.tar.gz and config.tar.gz from genesis.casperlabs.io for a specified protocol version and extracts them into /var/lib/bin/<protocol_version> and /etc/casper/<protocol_version>
  • config_from_example.sh - Gets external IP to replace and create the config.toml from config-example.toml
  • node_util.py - A script that will be replacing other scripts and is the preferred method of performing the actions of pull_casper_node_version.sh, config_from_example.sh, and delete_local_db.sh. Other scripts will be deprecated in future releases of casper-node-launcher.
  • casper-node-launcher-state.toml - The local state for the casper-node-launcher which is created during the first run
  • validator_keys/ - The default folder for node keys, containing:
    • README.md - Instructions on how to create validator keys using the casper-client
    • secret_key.pem - Secret key used by the validator node to sign blocks and peer-to-peer messages
    • public_key.pem - Public key associated with the secret key above, stored in PEM format
    • public_key_hex - Public key associated with the secret key above, stored in hex format
  • 1_0_0/ - Folder for genesis configuration files, containing:
    • accounts.toml - Contains the genesis validators and delegators
    • chainspec.toml - Contains invariant network settings, with the activation_point (network start time) as a timestamp
    • config-example.toml - Example for creating a config.toml file
    • config.toml - Contains variable node configuration settings, created by a node operator manually or by running config_from_example.sh 1_0_0
  • m_n_p/ - Folder for each installed upgrade package's configuration files, containing:
    • chainspec.toml - Contains invariant network settings, with the activation_point as an era ID (the era at which this protocol version of the node became or will become active)
    • config-example.toml - As per 1_0_0/config-example.toml, but compatible with the m.n.p version of the node
    • config.toml - As per 1_0_0/config.toml, but compatible with the m.n.p version of the node

/var/lib/casper/​

This is the location for larger and variable data for the casper-node, organized in the following folders and files:

  • bin/ - The parent folder storing the versions of casper-node executables. This location can be overwritten with the CASPER_BIN_DIR environment variable. The paths in this document assume the default of /var/lib/casper/bin/.

    • 1_0_0/ - Folder for genesis binary files, containing:
      • casper-node - The node executable - defaults to the Ubuntu 20.04 compatible binary
      • README.md - Information about the repository location and the Git hash used for compilation to allow a rebuild on other platforms
    • m_n_p/ - Folder for each installed upgrade package, containing:
      • casper-node - As per 1_0_0/casper-node, but the m.n.p version of the node
      • README.md - As per 1_0_0/README.md, but compatible with the m.n.p version of the node

  • casper-node/<NETWORK NAME> - Folder containing databases and related files produced by the node binary. For Mainnet, the network name is casper and for Testnet it is casper-test.

    • data.lmdb - Persistent global state store of the network
    • data.lmbd-lock - Lockfile for the data.lmdb database
    • storage.lmdb - Persistent store of all other network data, primarily Blocks and transactions
    • storage.lmdb-lock - Lockfile for the storage.lmdb database
    • unit_files/ - Folder containing transient caches of consensus information

Node Version Installation​

Included with the casper-node-launcher is node_util.py for installing casper-node versions. This command will stage all current casper-node versions:

sudo -u casper /etc/casper/node_util.py stage_protocols <NETWORK_CONFIG>

For <NETWORK_CONFIG>, we use casper.conf for Mainnet and casper-test.conf for Testnet. This will install all currently released protocols in one step.

This command will do the following:

  • Create /var/lib/casper/bin/1_0_2/ and expand the bin.tar.gz containing at a minimum casper-node
  • Create /etc/casper/1_0_2/ and expand the config.tar.gz containing chainspec.toml, config-example.toml, and possibly accounts.csv and other files
  • Remove the archive files and run /etc/casper/config_from_example.sh 1_0_2 to create a config.toml from the config-example.toml

Release versions are invoked using the underscore format, such as:

sudo -u casper /etc/casper/pull_casper_node_version.sh 1_0_2

The Node Configuration File​

One config.toml file exists for each casper-node version installed. It is located in the /etc/casper/[m_n_p]/ directory, where m_n_p is the current semantic version. This can be created from the config-example.toml by using /etc/casper/config_from_example.sh [m_n_p] where [m_n_p] is replaced with the current version, using underscores.

Below are some fields in the config.toml that you may need to adjust.

The Trusted Hash for Synchronizing​

Each Casper network is a permissionless, Proof-of-Stake network, implying that nodes can join and leave the network. As a result, some nodes may not be synchronized or as secure as bonded validators. Ideally, all nodes will join the network using a trusted source, such as a bonded validator.

When joining the network, the system will start from the hash of a recent block and then work backward to obtain the finalized blocks from the linear block store. Here is the process to get the trusted hash of a bonded validator:

  • Find a list of trusted validators
  • Query the status endpoint of a trusted validator (http://<NODE_IP_ADDRESS>:8888/status)
  • Obtain the hash of a block from the status endpoint
  • Update the config.toml for the node to include the trusted hash. There is a field dedicated to this near the top of the file

Here is an example command for obtaining a trusted hash. Replace the node address with an updated address from a node on the network.

sudo sed -i "/trusted_hash =/c\trusted_hash = '$(casper-client get-block --node-address http://3.14.161.135:7777 -b 20 | jq -r .result.block.hash | tr -d '\n')'" /etc/casper/1_0_0/config.toml

Known Addresses​

For the node to connect to a network, the node needs a set of trusted peers for that network. For Mainnet, these are listed in the config.toml as known_addresses. For other networks, locate and update the list to include at least two trusted IP addresses for peers in that network. Here is an example configuration. The casper-protocol-release repository stores configurations for various environments, which you can also use as examples.

Updating the config.toml file​

At the top of a config.toml file as shown here, enter the trusted block hash to replace the 'HEX-FORMATTED BLOCK HASH' and uncomment the line by deleting the leading '#'. See the Configuration File for more details.

# ================================
# Configuration options for a node
# ================================
[node]

# If set, use this hash as a trust anchor when joining an existing network.
#trusted_hash = 'HEX-FORMATTED BLOCK HASH'

Secret Keys​

Provide the path to the secret keys for the node. This path is set to etc/casper/validator_keys/ by default. See Creating Keys and Funding Accounts for more details.

Networking and Gossiping​

The node requires a publicly accessible IP address. The config_from_example.sh and node_util.py both allow IP for network address translation (NAT) setup. Specify the public IP address of the node. If you use the config_from_example.sh external services are called to find your IP and this is inserted into the config.toml created.

The following default values are specified in the file if you want to change them:

  • The port that will be used for status and transactions
  • The port used for networking
  • Known_addresses - these are the bootstrap nodes (there is no need to change these)

Enabling Speculative Execution​

The speculative_exec endpoint provides a method to execute a transaction without committing its execution effects to global state. This can be used by developers to roughly estimate the gas costs of sending the transaction in question. By default, speculative_exec is disabled on a node.

speculative_exec can be enabled within config.toml by changing enable_server to true under the configuration options for the speculative execution JSON-RPC HTTP server.

Node operators may also change the incoming request port for speculative execution, which defaults to 7778. Further, you can choose to alter the qps_limit and max_body_bytes, which limit the amount and size of requests to the speculative execution server.

Example Config.toml configuration with speculative execution enabled​

# ========================================================================
# Configuration options for the speculative execution JSON-RPC HTTP server
# ========================================================================
[speculative_exec_server]

# Flag which enables the speculative execution JSON-RPC HTTP server.
enable_server = true

# Listening address for speculative execution JSON-RPC HTTP server.  If the port
# is set to 0, a random port will be used.
#
# If the specified port cannot be bound to, a random port will be tried instead.
# If binding fails, the speculative execution JSON-RPC HTTP server will not run,
# but the node will be otherwise unaffected.
#
# The actual bound address will be reported via a log line if logging is enabled.
address = '0.0.0.0:7778'

# The global max rate of requests (per second) before they are limited.
# Request will be delayed to the next 1 second bucket once limited.
qps_limit = 1

# Maximum number of bytes to accept in a single request body.
max_body_bytes = 2_621_440

# Specifies which origin will be reported as allowed by speculative execution server.
#
# If left empty, CORS will be disabled.
# If set to '*', any origin is allowed.
# Otherwise, only a specified origin is allowed. The given string must conform to the [origin scheme](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Origin).
cors_origin = ''

Rust Client Installation​

The Prerequisites page lists installation instructions for the Casper client, which is useful for generating keys and retrieving information from the network.

Creating Keys and Funding Accounts​

The following command will create keys in the /etc/casper/validator_keys folder.

sudo -u casper casper-client keygen /etc/casper/validator_keys

To learn about other options for generating keys, see Accounts and Cryptographic Keys or run the Rust client keygen command with the --help option.

sudo -u casper casper-client keygen --help

More about keys and key generation can also be found in /etc/casper/validator_keys/README.md if the casper-node-launcher was installed from the Debian package.

note

Save your keys in a secure location, preferably offline.

To submit a bonding request, you will need to fund your account as well.

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