GraphQlMtaApiBackend

This is a fully serverless GraphQL backend for interacting with the NYC MTA API. It runs in AWS and is deployed using CDK.

This was previously the backend for closingdoors.nyc.

Components

• UpdateFeedsService: A Fargate service that takes a periodic snapshot of the MTA's real-time data feeds and persists them to S3 for consumption by other services.
• mtaApi: The AppSync instance that resolves GraphQL requests.
  • mtaNearestStation: a Lambda function that resolves the nearestStations query.
  • mtaTrainTimes: a Lambda function that resolves the trainTimes query.
  • mtaSystemMetadata: a DynamoDB table that resolves the systemMetadata query (see: mapping_templates folder).

Building and deploying

Environment

The following environment variables are used:

• CONTAINER_REGISTRY: the address of the container registry to push/pull the mta-feed-fetcher Docker image.
• OUTPUT_APPSYNC_DETAILS: if true, output the AppSync URL and API key after deployment. These are considered secrets and are not output in builds hosted on GitHub.

Docker

Before deploying the infrastructure, the mta-feed-fetcher Docker image needs to be built and published:

1. cd docker
2. ./build_and_push

This only needs to be done once initially and then subsequently when the image changes.

AWS resources

1. npm install && npm run build
2. cdk deploy --all

Related projects

• MTAPI
• Transiter