lambda

AWS Lambda

In this application we have 7 AWS Lambda functions:

• 6 of them are used like API calls (using the Amazon API Gateway service)
• 1 of them is triggered by a scheduler (using the Amazon CloudWatch service).

All functions are located in functions directory.
All unit tests are located in tests directory.

HTTP/Rest calls (API Gateway)

• add_participant - Adds a new participant into the current poll and returns the new participant ID. (REST POST method)

  Lambda policies/permisions (used DynamoDB operation - table):
  get_item - fp.config
  get_item - fp.polls
  query - fp.participants
  put_item - fp.participants

  Request body:

  {
      "person" : "",
      "friend" : ""
  }

• delete_participant - Deletes a participant from the current poll. (REST DELETE method)

  Lambda policies/permisions (used DynamoDB operation - table):
  get_item - fp.config
  delete_item - fp.participants

  Request body:

  {
      "participant_id" : ""
  }

• get_old_polls - Returns 5 polls at most, older than the oldest poll on the web site. (REST GET method)

  Lambda policies/permisions (used DynamoDB operation - table):
  batch_get_item - fp.polls

  Request body:

  {
      "last_poll" : ""
  }

• get_poll_participants - Returns all participants from the chosen poll. (REST GET method)

  Lambda policies/permisions (used DynamoDB operation - table):
  query - fp.participants

  Request body:

  {
      "poll_id" : ""
  }

• get_site_data - Returns all data needed to start the web site (current poll info, current poll participants, all persons - for stats, 3 polls older than the current). (REST GET method)

  Lambda policies/permisions (used DynamoDB operation - table):
  get_item - fp.config
  batch_get_item - fp.polls
  query - fp.participants
  scan - fp.persons

  Request body:

  {}

• update_current_poll - Updates the current poll info (end, dt, title, note, locDesc, locUrl, need, max - some of these or all). (REST PUT method)

  Lambda policies/permisions (used DynamoDB operation - table):
  get_item - fp.admins
  get_item - fp.config
  query - fp.participants
  update_item - fp.polls

  Request body:

  {
      "adimin_name" : "",
      "admin_password" : "",
      "title" : "",
      "note" : "",
      "locUrl" : "",
      "locDesc" : "",
      "max" : "",
      "need" : "",
      "end" : "",
      "dt" : ""
  }

Scheduled call (CloudWatch)

• check_if_current_poll_expired - Checks if the current poll is expired (if current date is greater than the end date from the current poll). If the current poll is expired then if there are enough participants updates the persons table with the participants from the current poll, otherwise deletes all participants, and at the end updates the current poll id in the config table and creates a new poll.
  This function will be executed (with the CloudWatch Event Rule that triggers on a schedule) every day after midnight at 00:05 (or 22:05 according to GMT, eu-central-1 region is GMT +2), cron expression: 5 22 * * ? *.

  Lambda policies/permisions (used DynamoDB operation - table):
  get_item - fp.config
  get_item - fp.polls
  query - fp.participants
  scan - fp.persons
  batch_write_item - fp.persons
  update_item - fp.persons
  put_item - fp.polls
  update_item - fp.config

Resources

Official AWS Amazon documentation about lambdas