OpenAQ Platform API

Overview

This is the main API for the OpenAQ project.

Starting with index.js, there is a web-accessible API that provides endpoints to query the air quality measurements. Documentation can be found at https://docs.openaq.org/.

openaq-fetch takes care of fetching new data and inserting into the database. Data format is explained in openaq-data-format.

Installing & Running

To run the API locally, you will need both Node.js and PostgreSQL installed.

Install necessary Node.js packages by running

npm install

Make sure you have a PostgreSQL database available (with PostGIS extension) and have the DB settings in knexfile.js.

npm test to seed the database.

Now you can get started with:

npm start

For production deployment, you will need to have certain environment variables set as in the table below (for production deployments, these are stored in an S3 bucket).

Name	Description	Default
API_URL	Base API URL after deployment	http://:3004
NEW_RELIC_LICENSE_KEY	New Relic API key for system monitoring	not set
WEBHOOK_KEY	Secret key to interact with openaq-api	'123'
USE_REDIS	Use Redis for caching?	not set (so not used)
USE_ATHENA	Use AWS Athena for aggregations?	not set (so not used)
REDIS_URL	Redis instance URL	redis://localhost:6379
DO_NOT_UPDATE_CACHE	Ignore updating cache, but still use older cached results.	not set
AGGREGATION_REFRESH_PERIOD	How long to wait before refreshing cached aggregations? (in ms)	45 minutes
REQUEST_LIMIT	Max number of items that can be requested at one time.	10000
UPLOADS_ENCRYPTION_KEY	Key used to encrypt upload token for /upload in database.	'not_secure'
S3_UPLOAD_BUCKET	The bucket to upload external files to for /upload.	not set

AWS Athena for aggregations

If USE_ATHENA is set, the API will use AWS Athena instead of creating Postgres aggregations tables for queries. The following variables should be set as well:

• ATHENA_ACCESS_KEY_ID: An AWS Access Key that has permissions to create Athena Queries and store them in S3.
• ATHENA_SECRET_ACCESS_KEY: The corresponding secret.
• ATHENA_OUTPUT_BUCKET: The S3 location (in the form of s3://bucket/folder) where the results of the Athena queries should be stored before caching them.
• ATHENA_FETCHES_TABLE: The name of the table registed in AWS Athena, default is fetches.fetches_realtime

The Athena table is fetches_realtime that represents the fetches from openaq-data and has the following schema:

CREATE EXTERNAL TABLE fetches.fetches_realtime (
  date struct<utc:string,local:string>,
  parameter string,
  location string,
  value float,
  unit string,
  city string,
  attribution array<struct<name:string,url:string>>,
  averagingPeriod struct<unit:string,value:float>,
  coordinates struct<latitude:float,longitude:float>,
  country string,
  sourceName string,
  sourceType string,
  mobile string
 )
 ROW FORMAT SERDE 'org.openx.data.jsonserde.JsonSerDe'
 LOCATION 's3://EXAMPLE_BUCKET'

Uploads & Generating S3 presigned URLs

Via an undocumented /upload endpoint, there is the ability to generate presigned S3 PUT URLs so that external clients can authenticate using tokens stored in the database and upload data to be ingested by openaq-fetch. There is a small utility file called encrypt.js that you can use like UPLOADS_ENCRYPTION_KEY=foo node index.js your_token_here to generate encrytped tokens to be manually stored in database.

Tests

To confirm that everything is working as expected, you can run the tests with

npm test

Dockerfile

There is a Dockerfile included that will turn the project into a Docker container. The container can be found here and is currently mostly used for deployment purposes for AWS ECS. If someone wanted to make it better for local development, that'd be a great PR!

Contributing

There are a lot of ways to contribute to this project, more details can be found in the contributing guide.

Projects using the API

• openaq-browser site | code - A simple browser to provide a graphical interface to the data.
• openaq code - An isomorphic Javascript wrapper for the API
• py-openaq code - A Python wrapper for the API
• ropenaq code - An R package for the API

For more projects that are using OpenAQ API, checkout the OpenAQ.org Community page.