Blockchains serve as foundational infrastructure that unblocks new use cases and introduces a new generation of decentralized applications by relying on a public ledger.
chainhook is a reorg-aware transaction indexing engine that helps developers get reliable blockchain data, regardless of forks and reorgs. By focusing only on the data devs care about, Chainhook helps developers work with much lighter datasets and build IFTTT logic into their applications.
Chainhook can be used as a tool in your local development environment and as a service in the cloud environment.
Key Features:
Benefits are plurals:
There are a few options when installing Chainhook.
Chainhook can be installed on macOS using Homebrew with the following command:
brew install chainhookChainhook is also available on the snap store for Linux users. To install, run:
sudo snap install chainhookWindows users can install via winget:
winget install HiroSystems.ChainhookIf you don't like using package managers and want to download our builds directly, they are published to our release page.
Finally, you can also build our source code directly:
$ git clone https://github.com/hirosystems/chainhook.git
$ cd chainhook
$ cargo chainhook-installif_this / then_that predicate designTo get started with Bitcoin predicates, we can use the chainhook to generate a template:
$ chainhook predicates new hello-ordinals.json --bitcoinWe will focus on the if_this and then_that parts of the specifications.
The current bitcoin predicates support the following if_this constructs:
// Get any transaction matching a given txid
// `txid` mandatory argument admits:
// - 32 bytes hex encoded type. example:
{
"if_this": {
"scope": "txid",
"equals": "0xfaaac1833dc4883e7ec28f61e35b41f896c395f8d288b1a177155de2abd6052f"
}
}
// Get any transaction, including an OP_RETURN output starting with a set of characters.
// `starts_with` mandatory argument admits:
// - hex encoded bytes. example: `0x589403`
{
"if_this": {
"scope": "outputs",
"op_return": {
"starts_with": "X2["
}
}
}
// Get any transaction, including an OP_RETURN output matching the sequence of bytes specified
// `equals` mandatory argument admits:
// - hex encoded bytes. example: `0x589403`
{
"if_this": {
"scope": "outputs",
"op_return": {
"equals": "0x69bd04208265aca9424d0337dac7d9e84371a2c91ece1891d67d3554bd9fdbe60afc6924d4b0773d90000006700010000006600012"
}
}
}
// Get any transaction including an OP_RETURN output ending with a set of characters
// `ends_with` mandatory argument admits:
// - hex encoded bytes. example: `0x589403`
{
"if_this": {
"scope": "outputs",
"op_return": {
"ends_with": "0x76a914000000000000000000000000000000000000000088ac"
}
}
}
// Get any transaction including a p2pkh output paying a given recipient
// `p2pkh` construct admits:
// - string type. example: "mr1iPkD9N3RJZZxXRk7xF9d36gffa6exNC"
{
"if_this": {
"scope": "outputs",
"p2pkh": {
"equals": "mr1iPkD9N3RJZZxXRk7xF9d36gffa6exNC"
}
}
}
// Get any transaction including a p2sh output paying a given recipient
// `p2sh` construct admits:
// - string type. example: "2MxDJ723HBJtEMa2a9vcsns4qztxBuC8Zb2"
{
"if_this": {
"scope": "outputs",
"p2sh": {
"equals": "2MxDJ723HBJtEMa2a9vcsns4qztxBuC8Zb2"
}
}
}
// Get any transaction including a p2wpkh output paying a given recipient
// `p2wpkh` construct admits:
// - string type. example: "bcrt1qnxknq3wqtphv7sfwy07m7e4sr6ut9yt6ed99jg"
{
"if_this": {
"scope": "outputs",
"p2wpkh": {
"equals": "bcrt1qnxknq3wqtphv7sfwy07m7e4sr6ut9yt6ed99jg"
}
}
}
// Get any transaction including a p2wsh output paying a given recipient
// `p2wsh` construct admits:
// - string type. example: "bc1qklpmx03a8qkv263gy8te36w0z9yafxplc5kwzc"
{
"if_this": {
"scope": "outputs",
"p2wsh": {
"equals": "bc1qklpmx03a8qkv263gy8te36w0z9yafxplc5kwzc"
}
}
}
// Get any Bitcoin transaction including a Block commitment.
// Broadcasted payloads include Proof of Transfer reward information.
{
"if_this": {
"scope": "stacks_protocol",
"operation": "block_committed"
}
}
// Get any transaction, including a key registration operation
{
"if_this": {
"scope": "stacks_protocol",
"operation": "leader_registered"
}
}
// Get any transaction, including an STX transfer operation
// Coming soon
{
"if_this": {
"scope": "stacks_protocol",
"operation": "stx_transferred"
}
}
// Get any transaction, including an STX lock operation
// Coming soon
{
"if_this": {
"scope": "stacks_protocol",
"operation": "stx_locked"
}
}
// Get any transaction including a new Ordinal inscription (inscription revealed and transferred)
{
"if_this": {
"scope": "ordinals_protocol",
"operation": "inscription_feed"
}
}
In terms of actions available, the following then_that constructs are supported:
// HTTP Post block / transaction payload to a given endpoint.
// `http_post` construct admits:
// - url (string type). Example: http://localhost:3000/api/v1/wrapBtc
// - authorization_header (string type). Secret to add to the request `authorization` header when posting payloads
{
"then_that": {
"http_post": {
"url": "http://localhost:3000/api/v1/wrapBtc",
"authorization_header": "Bearer cn389ncoiwuencr"
}
}
}
// Append events to a file through the filesystem. Convenient for local tests.
// `file_append` construct admits:
// - path (string type). Path to file on disk.
{
"then_that": {
"file_append": {
"path": "/tmp/events.json",
}
}
}Additional configuration knobs available:
// Ignore any block prior to given block:
"start_block": 101
// Ignore any block after given block:
"end_block": 201
// Stop evaluating chainhook after a given number of occurrences found:
"expire_after_occurrence": 1
// Include proof:
"include_proof": false
// Include Bitcoin transaction inputs in payload:
"include_inputs": false
// Include Bitcoin transaction outputs in payload:
"include_outputs": false
// Include Bitcoin transaction witness in payload:
"include_witness": false
Putting all the pieces together:
// Retrieve and HTTP Post to `http://localhost:3000/api/v1/wrapBtc`
// the 5 first transfers to the p2wpkh `bcrt1qnxk...yt6ed99jg` address,
// of any amount, occurring after block height 10200.
{
"chain": "bitcoin",
"uuid": "1",
"name": "Wrap BTC",
"version": 1,
"networks": {
"testnet": {
"if_this": {
"scope": "outputs",
"p2wpkh": {
"equals": "bcrt1qnxknq3wqtphv7sfwy07m7e4sr6ut9yt6ed99jg"
}
},
"then_that": {
"http_post": {
"url": "http://localhost:3000/api/v1/transfers",
"authorization_header": "Bearer cn389ncoiwuencr"
}
},
"start_block": 10200,
"expire_after_occurrence": 5,
}
}
}
// A specification file can also include different networks.
// In this case, the chainhook will select the predicate
// corresponding to the network it was launched against.
{
"chain": "bitcoin",
"uuid": "1",
"name": "Wrap BTC",
"version": 1,
"networks": {
"testnet": {
"if_this": {
"protocol": "ordinals",
"operation": "inscription_feed"
},
"then_that": {
"http_post": {
"url": "http://localhost:3000/api/v1/ordinals",
"authorization_header": "Bearer cn389ncoiwuencr"
}
},
"start_block": 10200,
},
"mainnet": {
"if_this": {
"protocol": "ordinals",
"operation": "inscription_feed"
},
"then_that": {
"http_post": {
"url": "http://my-protocol.xyz/api/v1/ordinals",
"authorization_header": "Bearer cn389ncoiwuencr"
}
},
"start_block": 90232,
}
}
}
In order to scan the Bitcoin chain with a given predicate, a bitcoind instance with access to the RPC methods getblockhash and getblock must be accessible. The RPC calls latency will directly impact the speed of the scans.
Note: the configuration of a bitcoind instance is out of scope for this guide.
Assuming a bitcoind node correctly configured, scans can be performed using the following command:
$ chainhook predicates scan ./path/to/predicate.json --testnetWhen using the flag --testnet, the scan operation will generate a configuration file in memory using the following settings:
[storage]
working_dir = "cache" # Directory used by chainhook node for caching data
[network]
mode = "testnet"
bitcoind_rpc_url = "http://0.0.0.0:18332"
bitcoind_rpc_username = "bitcoind_username"
bitcoind_rpc_password = "bitcoind_password"
# bitcoind_zmq_url = "tcp://0.0.0.0:18543"
[limits]
max_number_of_bitcoin_predicates = 100
max_number_of_concurrent_bitcoin_scans = 100
max_number_of_stacks_predicates = 10
max_number_of_concurrent_stacks_scans = 10
max_number_of_processing_threads = 16
max_number_of_networking_threads = 16
max_caching_memory_size_mb = 32000When using the flag --mainnet, the scan operation will generate a configuration file in memory using the following settings:
[storage]
working_dir = "cache"
[network]
mode = "testnet"
bitcoind_rpc_url = "http://0.0.0.0:8332"
bitcoind_rpc_username = "bitcoind_username"
bitcoind_rpc_password = "bitcoind_password"
# bitcoind_zmq_url = "tcp://0.0.0.0:18543"
[limits]
max_number_of_bitcoin_predicates = 100
max_number_of_concurrent_bitcoin_scans = 100
max_number_of_stacks_predicates = 10
max_number_of_concurrent_stacks_scans = 10
max_number_of_processing_threads = 16
max_number_of_networking_threads = 16
max_caching_memory_size_mb = 32000By passing the flag --config=/path/to/config.toml, developers can customize the credentials and network address of their Bitcoin node.
$ chainhook config new --testnet
✔ Generated config file Chainhook.toml
$ chainhook predicates scan ./path/predicate.json --config-path=./Testnet.tomlTips and tricks
To optimize their experience with scanning, developers have a few knobs they can play with:
start_block and end_block in predicates will drastically improve the speed.if_this / then_that predicate designTo get started with stacks predicates, we can use the chainhook to generate a template:
$ chainhook predicates new hello-arkadiko.json --stacksWe will focus on the if_this and then_that parts of the specifications.
The current stacks predicates support the following if_this constructs:
// Get any transaction matching a given txid
// `txid` mandatory argument admits:
// - 32 bytes hex encoded type. example: "0xfaaac1833dc4883e7ec28f61e35b41f896c395f8d288b1a177155de2abd6052f"
{
"if_this": {
"scope": "txid",
"equals": "0xfaaac1833dc4883e7ec28f61e35b41f896c395f8d288b1a177155de2abd6052f"
}
}
// Get any stacks block matching constraints
// `block_height` mandatory argument admits:
// - `equals`, `higher_than`, `lower_than`, `between`: integer type.
{
"if_this": {
"scope": "block_height",
"higher_than": 10000
}
}
// Get any transaction related to a given fungible token asset identifier
// `asset-identifier` mandatory argument admits:
// - string type, fully qualifying the asset identifier to observe. example: `ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.cbtc-sip10::cbtc`
// `actions` mandatory argument admits:
// - array of string type constrained to `mint`, `transfer` and `burn` values. example: ["mint", "burn"]
{
"if_this": {
"scope": "ft_event",
"asset_identifier": "ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.cbtc-token::cbtc",
"actions": ["burn"]
},
}
// Get any transaction related to a given non-fungible token asset identifier
// `asset-identifier` mandatory argument admits:
// - string type, fully qualifying the asset identifier to observe. example: `ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.monkey-sip09::monkeys`
// `actions` mandatory argument admits:
// - array of string type constrained to `mint`, `transfer` and `burn` values. example: ["mint", "burn"]
{
"if_this": {
"scope": "nft_event",
"asset_identifier": "ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.monkey-sip09::monkeys",
"actions": ["mint", "transfer", "burn"]
},
}
// Get any transaction moving STX tokens
// `actions` mandatory argument admits:
// - array of string type constrained to `mint`, `transfer`, `burn`, and `lock` values. example: ["mint", "lock"]
{
"if_this": {
"scope": "stx_event",
"actions": ["transfer", "lock"]
},
}
// Get any transaction emitting given print events predicate
// `contract-identifier` mandatory argument admits:
// - string type, fully qualifying the contract to observe. example: `ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.monkey-sip09`
// `contains` or `matches_regex` argument admits:
// - `contains` string type, used for matching events containing the specific string.
// - `matches_regex` string type that should be a valid regex, used for matching an event that regex matches with the specified string.
{
"if_this": {
"scope": "print_event",
"contract_identifier": "ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.monkey-sip09",
"contains": "vault"
},
}
{
"if_this": {
"scope": "print_event",
"contract_identifier": "ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.monkey-sip09",
"matches_regex": "(?:^|\\W)vault(?:$|\\W)"
}
}
// Get any transaction calling a specific method for a given contract **directly**.
// Warning: if the watched method is being called by another contract, this predicate won't detect it.
// `contract-identifier` mandatory argument admits:
// - string type, fully qualifying the contract to observe. example: `SP000000000000000000002Q6VF78.pox`
// `method` mandatory argument admits:
// - string type, used for specifying the method to observe. example: `stack-stx`
{
"if_this": {
"scope": "contract_call",
"contract_identifier": "SP000000000000000000002Q6VF78.pox",
"method": "stack-stx"
},
}
// Get any transaction, including a contract deployment
// `deployer` mandatory argument admits:
// - string "*"
// - string encoding a valid STX address. example: "ST2CY5V39NHDPWSXMW9QDT3HC3GD6Q6XX4CFRK9AG"
{
"if_this": {
"scope": "contract_deployment",
"deployer": "ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM"
},
}
// Get any transaction, including a contract deployment implementing a given trait (coming soon)
// `implement-trait` mandatory argument admits:
// - string type, fully qualifying the trait's shape to observe. example: `ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.sip09-protocol`
{
"if_this": {
"scope": "contract_deployment",
"implement_trait": "ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.sip09-protocol"
},
}In terms of actions available, the following then_that constructs are supported:
// HTTP Post block / transaction payload to a given endpoint.
// `http_post` construct admits:
// - url (string type). Example: http://localhost:3000/api/v1/wrapBtc
// - authorization_header (string type). Secret to add to the request `authorization` header when posting payloads
{
"then_that": {
"http_post": {
"url": "http://localhost:3000/api/v1/wrapBtc",
"authorization_header": "Bearer cn389ncoiwuencr"
}
}
}
// Append events to a file through the filesystem. Convenient for local tests.
// `file_append` construct admits:
// - path (string type). Path to file on disk.
{
"then_that": {
"file_append": {
"path": "/tmp/events.json",
}
}
}Additional configuration knobs available:
// Ignore any block prior to given block:
"start_block": 101
// Ignore any block after given block:
"end_block": 201
// Stop evaluating chainhook after a given number of occurrences found:
"expire_after_occurrence": 1
// Include decoded clarity values in payload
"decode_clarity_values": true
// Include the contract ABI for transactions that deploy contracts:
"include_contract_abi": truePutting all the pieces together:
// Retrieve and HTTP Post to `http://localhost:3000/api/v1/wrapBtc`
// the 5 first transactions interacting with ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.monkey-sip09,
// emitting print events containing the word 'vault'.
{
"chain": "stacks",
"uuid": "1",
"name": "Lorem ipsum",
"version": 1,
"networks": {
"testnet": {
"if_this": {
"scope": "print_event",
"contract_identifier": "ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.monkey-sip09",
"contains": "vault"
},
"then_that": {
"http_post": {
"url": "http://localhost:3000/api/v1/vaults",
"authorization_header": "Bearer cn389ncoiwuencr"
}
},
"start_block": 10200,
"expire_after_occurrence": 5,
}
}
}
// A specification file can also include different networks.
// In this case, the chainhook will select the predicate
// corresponding to the network it was launched against.
{
"chain": "stacks",
"uuid": "1",
"name": "Lorem ipsum",
"version": 1,
"networks": {
"testnet": {
"if_this": {
"scope": "print_event",
"contract_identifier": "ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.monkey-sip09",
"contains": "vault"
},
"then_that": {
"http_post": {
"url": "http://localhost:3000/api/v1/vaults",
"authorization_header": "Bearer cn389ncoiwuencr"
}
},
"start_block": 10200,
"expire_after_occurrence": 5,
},
"mainnet": {
"if_this": {
"scope": "print_event",
"contract_identifier": "SP456HQKV0RJXZFY1DGX8MNSNYVE3VGZJSRT459863.monkey-sip09",
"contains": "vault"
},
"then_that": {
"http_post": {
"url": "http://my-protocol.xyz/api/v1/vaults",
"authorization_header": "Bearer cn389ncoiwuencr"
}
},
"start_block": 90232,
"expire_after_occurrence": 5,
}
}
}
Developers can test their Stacks predicates without spinning up a Stacks node.
To date, the Stacks blockchain has just over 2 years of activity, and the chainhook utility is able to work with both testnet and mainnet chainstates, in memory.
To test a Stacks if_this / then_that predicate, the following command can be used:
$ chainhook predicates scan ./path/to/predicate.json --testnetThe first time this command run, a chainstate archive will be downloaded, uncompressed, and written to disk (around 3GB required for the testnet, 10GB for the mainnet).
The subsequent scans will use the cached chainstate if already present, speeding up iterations and the overall feedback loop.
chainhook as a service for streaming new blockschainhook can be run as a background service for streaming and processing new canonical blocks appended to the Bitcoin and Stacks blockchains.
When running chainhook as a service, if_this / then_that predicates can be registered by passing the path of the json file in the command line:
$ chainhook service start --predicate-path=./path/to/predicate-1.json --predicate-path=./path/to/predicate-2.json --config-path=./path/to/config.tomlPredicates can also be added dynamically. When the --predicate-path option is not passed or when the --start-http-api option is passed, chainhook will instantiate a REST API allowing developers to list, add, and removes predicates at runtime:
$ chainhook service start --config-path=./path/to/config.toml$ chainhook service start --predicate-path=./path/to/predicate-1.json --start-http-api --config-path=./path/to/config.tomlA comprehensive OpenAPI specification explaining how to interact with the Chainhook REST API can be found here.
If you encounter a bug or have a feature request, we encourage you to follow the steps below:
Please do not use the issue tracker for personal support requests or to ask for the status of a transaction. You'll find help at the #support Discord channel.
Development of this product happens in the open on GitHub, and we are grateful to the community for contributing bugfixes and improvements. Read below to learn how you can take part in improving the product.
Please read our Code of conduct since we expect project participants to adhere to it.
Read our contributing guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes.
Join our community and stay connected with the latest updates and discussions:
Join our Discord community chat to engage with other users, ask questions, and participate in discussions.
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