Sample Hydra Project

This is a sample project generated by hydra-cli scaffold. Experiment by modifying schema.graphql and the mappings in the mappings folder.

Prerequisites

• Node v14x

• Docker

Bootstrap

npm install

# make sure dependencies are deduped, this is important
npm dedupe

# generate TypeScript definitions for substrate types
npm run typegen

# Analyze schema.graphql and generate model/server files
npm run codegen

# Start postgres instance
docker-compose up -d

# Apply migrations related to processor's state keeping tables
npm run processor:migrate

# Analyze database state and create migration to match generated models
npm run db:create-migration

# Apply pending migrations
npm run db:migrate

# Now you can start processing chain data
npm run processor:start

# The above command will block
# Open separate terminal and launch graphql server to query the processed data
npm run query-node:start

Project structure

Hydra tools expect a certain directory layout explained here.

• generated - model/server definitions generated by codegen. Do not alter the contents of this directory.

• server-extension - a place for custom data models and resolvers defined via .model.ts, .resolver.ts files.

• chain - data type definitions for chain events and extrinsics generated by typegen,

  overridable via manifest.yml.

• mappings - mapping definitions, overridable via manifest.yml.

• .env - hydra tools are heavily driven by environment variables defined here.

Self-hosted indexer

It is recommeded to use already set up indexer if available, as new indexer typically requires some time to catch up with interesting events.

Have a look at ./indexer/docker-compose.yml for example of how you can set up a self-hosted version.