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hydra-indexer.md

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Hydra Indexer

Hydra Indexer is a daemon that ingests raw substrate data such as events and extrinsics from a substrate chain and saves it into a Postgres database. It is typically used in conjunction with Hydra Indexer Gateway providing a GraphQL API interface.

Installation

The indexer exits if an unrecoverable error occurs. It is therefore advisable to run the indexer with a process manager, such as PM2 or Docker.

Prerequisites

  • Node 12.x
  • Postgres database
  • Redis instances
  • (Optional) Docker

Environment variables

The indexer is set up using the following environment variables

Variable Default Required Description
WS_PROVIDER_ENDPOINT_URI - Yes Substrate API endpoint to connect
REDIS_URI - Yes Redis instance URI
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
DB_LOGGING error No TypeORM logging level
TYPES_JSON - No Path to a JSON type definition with custom Substrate types
BLOCK_HEIGHT 0 No Block height to start indexing. Ignored if the database already contains indexed blocks

Manual setup

Run

yarn && yarn build

For setting up the database and running the migrations, run yarn db:bootstrap. Make sure the environment variables DB_* are set.

For starting the indexer, run yarn start:prod.

Docker image

There are pre-built runnable docker images in joystream/hydra-indexer docker repo. The default command is yarn start:prod.

First, bootstrap the database:

docker run -e DB_HOST=... -e DB_PORT=... -e DB_NAME=... -e DB_PASS=... -e DB_USER=... joystream/hydra-indexer sh -c 'yarn db:bootstrap'

Then run the indexer (make sure that all the required environment variables are set)

docker run -e ... joystream/hydra-indexer

Advanced environment variables

Some optional environment variables are available for fine-tuning.

Variable Default Description
BLOCK_CACHE_TTL_SEC 60*60 TTL for processed blocks in the Redis cache
INDEXER_HEAD_TTL_SEC 60*15 TTL for the indexer head block entry
WORKERS_NUMBER 5 Number of concurrent workers fetching the blocks
BLOCK_PRODUCER_FETCH_RETRIES 3 Number of attempts fetching each a block before throwing an error. Set to -1 for indefinite attempts
SUBSTRATE_API_TIMEOUT 1000 * 60 * 5 Timeout in (milliseconds) for API calls
NEW_BLOCK_TIMEOUT_MS 60 * 10 * 1000 Panic if no blockchain blocks have been received within this time