├── README.md
├── handler.js
├── package.json
└── serverless.yml


/README.md:
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 1 | # Serverless Lambda chaining
 2 | 
 3 | Serverless service which shows how one can chain Lambdas through SNS.
 4 | The [configuration](https://serverless.com/framework/docs/providers/aws/events/sns/#sns) which triggers the chain mechanims is defined on [serverless.yml](/serverless.yml). 
 5 | 
 6 | ## Installation
 7 | 
 8 | Make sure that you use Serverless v1.
 9 | 
10 | 1. Run `serverless install --url https://github.com/pmuens/serverless-lambda-chaining` to install the service in your current working directory
11 | 2. Next up cd into the service with `cd serverless-lambda-chaining`
12 | 3. Run `npm install`
13 | 4. Replace the `accountId` in the `handler.js` file with your AWS account id
14 | 5. Deploy with `serverless deploy`
15 | 
16 | ## How to use
17 | 
18 | 1. Run `serverless invoke --function firstLambda` to trigger the chaining process (this will publish a message to the SNS topic called `dispatcher` the `secondLambda` will listen to)
19 | 2. Run `serverless logs --function secondLambda` to see that the message which was send to the `dispatcher` topic successfully triggered the `secondLambda` function
20 | 
21 | ## AWS services used
22 | 
23 | - Lambda
24 | - SNS
25 | 
26 | ## References
27 | https://serverless.com/framework/docs/providers/aws/events/sns/#sns
28 | 


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/handler.js:
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 1 | 'use strict';
 2 | 
 3 | const AWS = require('aws-sdk');
 4 | 
 5 | module.exports.firstLambda = (event, context, callback) => {
 6 |   const sns = new AWS.SNS();
 7 | 
 8 |   const accountId = '<account-id>';
 9 | 
10 |   const params = {
11 |     Message: 'triggering other Lambda(s)',
12 |     TopicArn: `arn:aws:sns:us-east-1:${accountId}:dispatcher`
13 |   };
14 | 
15 |   sns.publish(params, (error, data) => {
16 |     if (error) {
17 |       callback(error);
18 |     }
19 |     callback(null, { message: 'Message successfully published to SNS topic "dispatcher"', event });
20 |   });
21 | };
22 | 
23 | module.exports.secondLambda = (event, context, callback) => {
24 |   // print out the event information on the console (so that we can see it in the CloudWatch logs)
25 |   console.log(`I'm triggered by "firstLambda" through the SNS topic "dispatcher":\n${JSON.stringify(event, null, 2)}`);
26 | 
27 |   callback(null, { event });
28 | };
29 | 


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/package.json:
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 1 | {
 2 |   "name": "serverless-lambda-chaining",
 3 |   "version": "0.1.0",
 4 |   "description": "Serverless service which shows how one can chain Lambdas through SNS",
 5 |   "scripts": {
 6 |     "test": "echo \"Error: no test specified\" && exit 1"
 7 |   },
 8 |   "author": "",
 9 |   "license": "MIT",
10 |   "dependencies": {
11 |     "aws-sdk": "^2.6.7"
12 |   }
13 | }
14 | 


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/serverless.yml:
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 1 | service: serverless-lambda-chaining
 2 | 
 3 | provider:
 4 |   name: aws
 5 |   runtime: nodejs4.3
 6 |   region: us-east-1
 7 |   stage: dev
 8 |   iamRoleStatements:
 9 |     - Effect: "Allow"
10 |       Resource: "*"
11 |       Action:
12 |         - "sns:*"
13 | 
14 | functions:
15 |   firstLambda:
16 |     handler: handler.firstLambda
17 |   secondLambda:
18 |     handler: handler.secondLambda
19 |     events:
20 |       - sns: dispatcher
21 | 


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