Hydra Processor

Hydra processor is a client-side 'sink' tool used to fetch substrate events from a Hydra indexer. It sequentially applies the event handlers one by one in the order the events have been emitted.

Commands

• hydra-processor help [COMMAND]

• hydra-processor migrate

• hydra-processor run

hydra-processor help [COMMAND]

display help for hydra-processor

display help for <%= config.bin %>

USAGE
  $ hydra-processor help [COMMAND]

ARGUMENTS
  COMMAND  command to show help for

OPTIONS
  --all  see all commands in CLI

See code: @oclif/plugin-help

hydra-processor migrate

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USAGE
  $ hydra-processor migrate

OPTIONS
  -e, --env=env  Path to a file with environment variables

hydra-processor run

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USAGE
  $ hydra-processor run

OPTIONS
  -e, --env=env            Path to a file with environment variables
  -m, --manifest=manifest  Manifest file
  --id=id                  ID of the processor (useful for multi-processor setups)
  --indexer=indexer        Indexer URL to source events

Qickstart

Before the first run, the processor should set up auxiliary database tables required for its stable work:

hydra-processor migrate

Then hydra-processor can be run against the manifest file (by default, it looks up manifest.yml in the current folder)

hydra-processor run -m <path/to/manifest> -e <path to a file with env variables>

Environment variables

Hydra processor requires a manifest file and certain environment variables to be set.

Variable	Default	Required	Description
INDEXER_ENDPOINT_URL	-	Yes	Hydra indexer endpoint to source the raw event and extrinsic data
MANIFEST_PATH	manifest.yml	No	Path to the manifest file
DB_NAME	-	Yes	Database name
DB_PORT	-	Yes	Database port
DB_HOST	-	Yes	Database host
DB_USER	-	Yes	Database user
DB_PASS	-	Yes	Database password
PROMETHEUS_PORT	3000	No	A prometheus metrics endpoint is started at this port
POLL_INTERVAL_MS	1 sec (60000 msec)	No	How often the processor polls the indexer for new blocks

The required variables can either be set externally or loaded from a file using the -e flag, e.g.:

hydra-processor migrate -e .env

Manifest file

The manifest file describes which and how the events and extrinsics should be processed. Here is an example for Kusama blockchain:

version: '0.1'
description: Test manifest
repository: https://github.com/
## currently only these settings for the datasouce section are accepted
dataSource:
  kind: substrate 
  chain: kusama
  indexerVersion: '0.0.4'
# compiled model classes generated by hydra-cli codegen from the input schema 
entities:
  - mappings/lib/generated/**/*.model.js
mappings:
  hydraCommonVersion: '0.0.3'
  # process only blocks with height >= 1M 
  blockInterval: '[1000000,]'
  # js module that exports the handler functions 
  mappingsModule: mappings/lib/mappings
  # additinal libraries the processor loads
  # typically it is a module with event and extrinsic types generated by hydra-typegen 
  imports:
    - mappings/lib/mappings/generated/types
  eventHandlers:
  # event name
    - event: balances.Transfer 
  # function handler name with the argument types
      handler: balancesTransfer(DatabaseManager, Balances.TransferEvent)
  extrinsicHandlers:
    # infer defaults here
    #- extrinsic: Balances.Transfer 
    #- extrinsic: Sudo.batchCall 
    #  handler: handleSudoCall(DatabaseManager,SubstrateEvent)
  preBlockHooks:
  postBlockHooks: