Quick Start


This is a quick start guide. If you have a vague idea about how CometBFT works and want to get started right away, continue.


See the install guide.



cometbft init

will create the required files for a single, local node.

These files are found in $HOME/.cometbft:

$ ls $HOME/.cometbft

config  data

$ ls $HOME/.cometbft/config/

config.toml  genesis.json  node_key.json  priv_validator.json

For a single, local node, no further configuration is required. Configuring a cluster is covered further below.

Local Node

Start CometBFT with a simple in-process application:

cometbft node --proxy_app=kvstore

Note: kvstore is a non persistent app, if you would like to run an application with persistence run --proxy_app=persistent_kvstore

and blocks will start to stream in:

I[01-06|01:45:15.592] Executed block                               module=state height=1 validTxs=0 invalidTxs=0
I[01-06|01:45:15.624] Committed state                              module=state height=1 txs=0 appHash=

Check the status with:

curl -s localhost:26657/status

Sending Transactions

With the KVstore app running, we can send transactions:

curl -s 'localhost:26657/broadcast_tx_commit?tx="abcd"'

and check that it worked with:

curl -s 'localhost:26657/abci_query?data="abcd"'

We can send transactions with a key and value too:

curl -s 'localhost:26657/broadcast_tx_commit?tx="name=satoshi"'

and query the key:

curl -s 'localhost:26657/abci_query?data="name"'

where the value is returned in hex.

Cluster of Nodes

First create four Ubuntu cloud machines. The following was tested on Digital Ocean Ubuntu 16.04 x64 (3GB/1CPU, 20GB SSD). We’ll refer to their respective IP addresses below as IP1, IP2, IP3, IP4.

Then, ssh into each machine and install CometBFT following the instructions.

Next, use the cometbft testnet command to create four directories of config files (found in ./mytestnet) and copy each directory to the relevant machine in the cloud, so that each machine has $HOME/mytestnet/node[0-3] directory.

Before you can start the network, you’ll need peers identifiers (IPs are not enough and can change). We’ll refer to them as ID1, ID2, ID3, ID4.

cometbft show_node_id --home ./mytestnet/node0
cometbft show_node_id --home ./mytestnet/node1
cometbft show_node_id --home ./mytestnet/node2
cometbft show_node_id --home ./mytestnet/node3

Finally, from each machine, run:

cometbft node --home ./mytestnet/node0 --proxy_app=kvstore --p2p.persistent_peers="ID1@IP1:26656,ID2@IP2:26656,ID3@IP3:26656,ID4@IP4:26656"
cometbft node --home ./mytestnet/node1 --proxy_app=kvstore --p2p.persistent_peers="ID1@IP1:26656,ID2@IP2:26656,ID3@IP3:26656,ID4@IP4:26656"
cometbft node --home ./mytestnet/node2 --proxy_app=kvstore --p2p.persistent_peers="ID1@IP1:26656,ID2@IP2:26656,ID3@IP3:26656,ID4@IP4:26656"
cometbft node --home ./mytestnet/node3 --proxy_app=kvstore --p2p.persistent_peers="ID1@IP1:26656,ID2@IP2:26656,ID3@IP3:26656,ID4@IP4:26656"

Note that after the third node is started, blocks will start to stream in because >2/3 of validators (defined in the genesis.json) have come online. Persistent peers can also be specified in the config.toml. See here for more information about configuration options.

Transactions can then be sent as covered in the single, local node example above.

Decorative Orb