version: "3.6"
services:
  db:
    container_name: db
    image: postgres:9.6
    ports:
      - "5432:5432"
    environment:
      - POSTGRES_PASSWORD=sample
      - POSTGRES_USER=sample
      - POSTGRES_DB=airtng-servlets
  app:
    stdin_open: true
    tty: true
    environment:
      - TWILIO_ACCOUNT_SID=your_account_sid
      - TWILIO_AUTH_TOKEN=your_account_token
      - TWILIO_PHONE_NUMBER=your_twilio_number
    build: .
    ports: 
      - "8080:8080"
    links:
      - db

version: "3.6"
services:
  db:
    image: postgres:9.6
    ports:
      - "5432:5432"
    environment:
      - POSTGRES_PASSWORD=sample
      - POSTGRES_USER=sample
      - POSTGRES_DB=airtng-servlets
  app:
    stdin_open: true
    tty: true
    environment:
      - TWILIO_ACCOUNT_SID=your_account_sid
      - TWILIO_AUTH_TOKEN=your_account_token
      - TWILIO_PHONE_NUMBER=your_twilio_number
    build: .
    ports: 
      - "8080:8080"
    links:
      - db

Remove container_name from db container
Remove container_name from db container
