Sample Hydra Project

It is a sample Hydra v2 project for Subsocial network. It was created with hydra-cli scaffold. he

1. Bootstrap

Run

yarn && yarn bootstrap

It will generate the model files as defined in schema.graphql, create the database and run all the necessary migrations in one shot.

NB! Use with caution in production, as it will delete all the existing records.

2. Generate Types for events and extrinsics

A separate tool Hydra Typegen can be used for generating Typescript classes for the event handlers (the mappings).
Run

yarn typegen

to run the typegen for events and extrinsics defined in manifest.yml (it fetches the metadata from an RPC endpoint and blockhash defined there).

3. Build Mappings

Mappings is a separated TypeScript module created in the mappings folder. The handlers exported by the module should match the ones defined in manifest.yml in the mappings section. Once the necessary files are generated, build it with

yarn workspace sample-mappings install
yarn mappings:build

4. Run local Hydra Indexer

A stack of Hydra Indexer services is configured in docker-compose-indexer.yml. Run

$ docker-compose -f docker-compose-indexer.yml up -d

and check the status at localhost:4001 by quering

query {
  indexerStatus {
    chainHeight
    head
    hydraVersion
  }
}

Make sure that the last indexer block (head) and the last known finalized block (chainHeight) are both positive and hydraVersion is 2.x.

5. Run the processor and the GraphQL server

Then run the processor:

yarn processor:start

Afterwards, start the GraphQL server in a separate terminal (opens a GraphQL playground at localhost by default):

yarn query-node:start:dev

Running in Docker

Docker files are located in ./docker. First, build the builder image:

$ docker build . -f docker/Dockerfile.builder -t builder

Images for the GraphQL query node and the processor depend on the builder image which is now available. Build with

$ docker build . -f docker/Dockerfile.query-node -t query-node:latest
$ docker build . -f docker/Dockerfile.processor -t processor:latest

In order to run the docker-compose stack, we need to create the schema and run the database migrations.

$ docker-compose up -d db 
$ yarn docker:db:migrate

The last command runs yarn db:bootstrap in the builder image. A similar setup strategy may be used for Kubernetes (with builder as a starter container).

Now everything is ready:

$ docker-compose up