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pypi build codecoverage


Build Tendermint blockchain applications in Python. It's fun. This library provides the core functionality needed to create Tendermint ABCI applications.

Supported Tendermint Version

  • Tendermint 0.34.11
  • ABCI 0.17.0


Requires Python >= 3.9

pip install abci

You'll need a binary version of the Tendermint engine. Available here:

Make sure the Tendermint version you download matches the current support version of this library

Quick Start - demo

A very simple demo application is included and available from the command line as counter. You can find the code here:

To try it out:

  1. Make sure you have the Tendermint binary setup locally and in your path. To test it's working open a terminal window and type:
>> tendermint version

It should output your version of Tendermint that should match the currently supported version of this library.

  1. Next, initialize Tendermint by running:
>> tendermint init
  1. Start the Tendermint node:
>> tendermint node

The node will start, but will be waiting for you application to start.

  1. Open another terminal, and start the counter application. The counter will be available from within the Python environment where you installed abci
>> counter

You'll see the application start, and in the Tendermint terminal, you'll see the output of blocks being produced

  1. Now, open a 3rd terminal window to send some transaction to the blockchain. To do this we'll use the curl application to send transaction to the local blockchain over http. For example:
>> curl http://localhost:26657/broadcast_tx_commit?tx=0x01
>> curl http://localhost:26657/broadcast_tx_commit?tx=0x02

The counter application expects you to send transactions as numbers encoded as hex in order: 1,2,3... It will reject and out-of-order numbers. You can always see the latest accepted value by sending the request:

>> curl http://localhost:26657/abci_query

To shut down the application enter CTRL-C

Get Started

To start building your own application:

  1. Extend the abci.application.BaseApplication class
  2. Implement the Tendermint ABCI callbacks - see for details on how they work
  3. Start it:
from abci.server import ABCIServer

app = ABCIServer(app=MyApplication())

See the application in the example directory for a full example.

Developing on the code base

If you're working directly on the code base. Install a local editable version:

pip install --editable '.[test]'

Updating Protobuf code

You should only re-generate the protobuf code if you're updating the associated protobuf files, and/or contributing to this code base. You do not need to rebuild protos to create apps.

A note on protobuf: The primary code directory is abci, but you'll notice additional directories: gogoproto, tendermint, and protos.

The gogoproto and tendermint directories are the protobuf generated code used by abci. It adds proper Python modules and preserves all the import statements used by Tendermint for the various protobuf files spread across their codebase. The protos directory is the source .proto files.

To (re)build the protobuf files:

  1. Install protoc so it's available in your PATH as a command
  2. Run make update-proto