indexing-config

name	indexing-config
description	Use when writing or editing config.yaml. Chain/contract structure, addresses, start_block, event selection, field_selection, custom event names, env vars, address_format, schema/output paths, YAML validation, and deprecated options.

Config Reference (config.yaml)

Structure Overview

name: my-indexer
description: Optional description
schema: schema.graphql         # custom path (default: schema.graphql)
output: generated/             # custom output path (default: generated/)
address_format: checksum       # checksum (default) | lowercase

contracts:
  - name: MyContract
    abi_file_path: ./abis/MyContract.json
    handler: ./src/EventHandlers.ts  # optional — auto-discovered from src/handlers/
    events:
      - event: Transfer(address indexed from, address indexed to, uint256 value)

chains:
  - id: 1
    start_block: 0
    contracts:
      - name: MyContract
        address: "0x1234..."

Uses chains (not networks) and max_reorg_depth (not confirmed_block_threshold).

Contract Addresses

# Single address
- name: Token
  address: "0x1234..."

# Multiple addresses
- name: Token
  address:
    - "0xaaa..."
    - "0xbbb..."

# No address — wildcard indexing (all contracts matching ABI)
- name: Token
  # address omitted — indexes all matching events chain-wide

# Factory-registered — see indexing-factory skill

For proxied contracts, use the proxy address (where events emit), not the implementation.

start_block

chains:
  - id: 1
    start_block: 0            # 0 = HyperSync auto-detects first event block
    contracts:
      - name: Token
        address: "0x1234..."
        start_block: 18000000  # per-contract override (takes precedence)

start_block: 0 with HyperSync skips empty blocks automatically.

Custom Event Names

When two events share the same name (different signatures), disambiguate:

events:
  - event: Transfer(address indexed from, address indexed to, uint256 value)
    name: TransferERC20
  - event: Transfer(address indexed from, address indexed to, uint256 indexed tokenId)
    name: TransferERC721

field_selection

Request additional transaction/block fields globally or per event:

# Global (root level — applies to all events)
field_selection:
  transaction_fields:
    - hash
    - from
    - to
  block_fields:
    - number
    - timestamp

contracts:
  - name: MyContract
    events:
      # Per-event (overrides global for this event)
      - event: Transfer(address indexed from, address indexed to, uint256 value)
        field_selection:
          transaction_fields:
            - hash
            - from
            - to
            - gasPrice

Global field_selection is at the root level (sibling to contracts and chains). Per-event field_selection is directly under the event entry. See indexing-transactions skill for full field lists.

Environment Variables

rpc:
  - url: ${ENVIO_RPC_URL}                    # required — errors if missing
  - url: ${ENVIO_RPC_URL:-http://localhost:8545}  # with default value

Works in any string value in config. Set via .env file or shell environment.

IMPORTANT: All environment variables MUST use the ENVIO_ prefix (e.g., ENVIO_RPC_URL, not RPC_URL). The hosted service requires the ENVIO_ prefix — variables without it will not be available at runtime.

YAML Validation

Add at top of file for IDE schema validation:

# yaml-language-server: $schema=./node_modules/envio/evm.schema.json

Deprecated Options (Do NOT Use)

• loaders / preload_handlers — replaced by async handler API
• preRegisterDynamicContracts — replaced by contractRegistrations in factory pattern
• event_decoder — removed
• rpc_config — replaced by rpc: under chains
• unordered_multichain_mode — removed

RPC Configuration

RPC tuning parameters are documented in the indexing-performance skill.

Deep Documentation

Full reference: https://docs.envio.dev/docs/HyperIndex-LLM/hyperindex-complete