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blockchain-importer

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TLDR: Functional, typesafe, well-tested and composable streaming blockchain importer, drop-in solution for and leverages Kafka ecosystem. Aims for no-code and great developer experience.

Blockchain-importer is the first-of-its-kind open-source software that enables typesafe agnostic real-time streaming of Blockchain data into different sinks and primiarily into the Kafka ecosystem (in Avro and from here leveraging fault tolerance, exactly-once). It currently supports Bitcoin, but any block/transaction-based ledger can be added easily. It is therefore very different from the data science use case of Python/SQL-based analytics in AWS/GCP where other projects are more suited such as bitcoin-etl, ethereum-etl. If you need to just read from the full node in a typesafe way, have a look at the blockchain-rpc project.

For any questions or support please visit our gitter channel.

Quickstart

The following commands will create a docker container setup with a Kafka broker, Schema registry, Zookeeper, PostgreSQL and the blockchain-importer. It will start ingesting blocks, transactions and scripts into Kafka topics starting from genesis block. Please change RPC settings in the docker-compose file minimal.yml to point to the RPC server your Bitcoin full node (with txindex=1 in config).

    # vim docker/minimal.yml (modify RPC settings)
    # docker-compose -f docker/minimal.yml up

Table of Contents

  1. Modes
  2. Avro Protocol
  3. Configuration
  4. Running a full node
  5. Build your own Docker image

Modes

Blockchain-importer has two distinct modes lagging and push, pushverify which allows a consumer to select the type of subscription that is adequate for the existing streaming infrastructure.

The lagging mode is widely used in lots of different Blockchain data companies and it maintains a distance between the current processed block and the tip of the chain. This approach ensures that wrong blocks due to blockchain reorganizations are not propagated downstream. The push mode is reading from the tip of the chain and is propagating the last mined block. This mode does not guarantee that only correct blocks are forwarded. Therefore, pushverify has been introduced which additionaly checks if there was a reorganization and replays the missed canonical blocks.

Modes cheatsheet

mode description use cases
lagging polling-based: maintains a distance between the current processed block and the tip of the chain high-latency, store in data lake
push push-based: reads from the tip of the chain, on each new mined block low-latency, trading with onchain data, ignore reorgs
pushverify like push, but also replays missed out blocks on reorganization low-latency, mission critical, upsert correct data

Avro Protocol

The Bitcoin protocol in blockchain-importer is specified in Avro as Block, Coinbase, Transaction, Input, Output and Script. The definition is encoded as case classes in Scala using avro4s.

Configuration

variable description type
BLOCKCHAIN type of blockchain to extract String
MODE push, pushverify or lagging String
LAG_BEHIND if in lagging mode, sets lag behind Integer
POLL_TIME_MS if in lagging mode, sets poll time Long
BLOCKCHAIN_RPC_HOSTS Comma-seperated list of IPs or hostname of full nodes IP,IP
BLOCKCHAIN_RPC_USERNAME RPC username String
BLOCKCHAIN_RPC_PASSWORD RPC password String
BLOCKCHAIN_RPC_PORT JSON-RPC port Optional Int
BLOCKCHAIN_RPC_ZEROMQ_PORT ZeroMQ port Optional port
SCHEMA_REGISTRY Schema registry URL URL with port
BROKERS Kafka broker list Comma seperated list of host:ip of brokers
KAFKA_TRANSACTIONAL_ID Transactional producer id String
KAFKA_TOPIC_PREFIX Topic prefix for topics to push to *-transactions String
DB_HOST Postgres host ip IP address
DB_NAME Postgres database name String
DB_USER Postgres user String
DB_PASS Postgres password String
DB_OFFSET_NAME Extractor name under which store the offset String
IN_MEMORY_OFFSET Temporary in-memory blockchain offset when running locally String

Running a full node

  • Instead of AWS/GCP use a dedicated server provider, these are much cheaper.
  • Make sure your chaindata is on a SSD. Bootstrapping from genesis block is much faster.
  • Make sure the RPC server is not reachable from the outside and set username/password.

Building your own Docker image

    $ vim build.sbt (change organization name, top of file)
    $ sbt docker

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Functional, typesafe, well-tested and composable streaming blockchain importer, drop-in solution for Kafka ecosystem.

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