Serverless lambda hack for python

README.md

The serverless-offline module handles node.js modules, but sls invoke will handle modules for python. So just create a node.js module with the same name as the python module, and a method with the same same which calls sls invoke ... and wallah!

serverless.yaml

service: serverless-flask

provider:
  name: aws
  runtime: python2.7
  region: ${self:custom.region}

plugins:
  - serverless-python-requirements
  - serverless-wsgi
  - serverless-s3-local
  - serverless-dynamodb-local
  - serverless-offline-sns
  - serverless-offline

custom:
  accountId: 0123456789012
  region: us-west-1
  topicName: report_parser

  wsgi:
    host: 0.0.0.0
    app: app.app
    packRequirements: false
  pythonRequirements:
    dockerizePip: true
  serverless-offline-sns:
    port: 4002
    debug: true 
    accountId: ${self:custom.accountId}
  s3:
    host: 0.0.0.0
    port: 8006
    directory: ./data/s3
  dynamodb:
    start:
      host: 0.0.0.0
      port: 8007
      inMemory: true
    #  migrate: true
    #  seed: true
    #seed:
    #  users:
    #    sources:
    #      - table: users
    #        sources: [./test/users.json]
  serverless-offline:
    port: 4000
    region: ${self:custom.region}
    debug: true


package:
  exclude:
    - node_modules/**
    - venv/**

resources:
  Resources:
    NewResource:
      Type: AWS::S3::Bucket
      Properties:
        BucketName: local-bucket

functions:
  app:
    handler: wsgi.handler
    events:
      - http: ANY /
      - http: 'ANY {proxy+}'
  # report_parser:
  #  handler: tasks.report_parser # required, handler set in AWS Lambda
    # name: bnsec.report_parser
  #  description: Description of what the lambda function does 
  #  runtime: python2.7
  #  memorySize: 512
  #  timeout: 10
  #  reservedConcurrency: 5 
  #  events:
  #    - sns: ${self:custom.topicName} 
      #- s3:
      #    bucket: local-bucket
      #    event: s3:ObjectCreated:*
  report_parser:
    handler: tasks.report_parser # required, handler set in AWS Lambda
    description: Description of what the lambda function does 
    runtime: python2.7
    memorySize: 512
    timeout: 10
    reservedConcurrency: 5 
    events:
      - sns: ${self:custom.topicName} 
      - s3:
          bucket: local-bucket
          event: s3:ObjectCreated:*

tasks.js

'use strict';

var fs = require('fs');
var cp = require('child_process');

function genericInvoke(event, context, callback) {
  let dataFile = `/tmp/invoke-data-${Date.now()}.json`;
  let data = JSON.stringify(event);

  fs.writeFile(dataFile, data, function (err) {
    cp.execFile('sls', ['invoke', 'local', '--function', 'report_parser', '--path', dataFile], {
      cwd: '/app',
    }, (error, stdout, stderr) => {
      if (error) {
        console.log("INVOKE_ERROR", error)
        console.log(stderr)
        return callback(error);
      }
      console.log("INVOKE_OUT", stdout);
      callback();
    });
  });
}

module.exports.report_parser = genericInvoke;

tasks.py

import json

def report_parser(event, context):
  print(event)