Multi-process Node.js application example

The application consists of 3 processes:

• twitter-stream-worker
• social-preprocessor-worker
• web

Processes

Use the PROCESS_TYPE environment variable to select the process to be run.

$ PROCESS_TYPE=web NODE_ENV=production npm start

Twitter stream worker

The process is listening on twitter for keywords and sends the tweets to a RabbitMQ queue.

Environment variables

• NODE_ENV ('development' | 'production'): when development, it uses dotenv, to read the local .env file, that's the only difference
• LOGGER_LEVEL ('error' | 'warn' | 'info' | 'verbose' | 'debug' | 'silly'), default: info
• LOGGER_ENABLED ('true' | 'false'), default: true
• TWITTER_CONSUMER_KEY
• TWITTER_CONSUMER_SECRET
• TWITTER_ACCESS_TOKEN_KEY
• TWITTER_ACCESS_TOKEN_SECRET
• TWITTER_TRACK: comma separated keywords to track, eg. nodejs,node.js,risingstack,microservice,micro-service
• RABBITMQ_URI

Social preprocessor worker

The process is listening on the RabbitMQ queue and saves the tweets to Redis and removes old ones.

Environment variables

• NODE_ENV ('development' | 'production'): when development, it uses dotenv, to read the local .env file, that's the only difference
• LOGGER_LEVEL ('error' | 'warn' | 'info' | 'verbose' | 'debug' | 'silly'), default: info
• LOGGER_ENABLED ('true' | 'false'), default: true
• RABBITMQ_URI
• REDIS_URI
• REDIS_DATA_RETENTION_IN_MS, default: 86400000 (1 day)

Web

The process is serving an HTTP API to return the tweets.

• GET /api/v1/tweets?limit&offset

Environment variables

• NODE_ENV ('development' | 'production'): when development, it uses dotenv, to read the local .env file, that's the only difference
• LOGGER_LEVEL ('error' | 'warn' | 'info' | 'verbose' | 'debug' | 'silly'), default: info
• LOGGER_ENABLED ('true' | 'false'), default: true
• REDIS_URI
• PORT