aws-lambda Serverless Framework Create Simple CRUD Operation

Example

Create simple CRUD Operation Using Serverless Framework

Install Serverless framework globally

npm install serverless -g

Create simple Lambda Service

serverless create --template aws-nodejs --path myService

Go to the myService Directory it should contain

1. serverless.yml
2. handler.js
3. event.json

All Serverless service configuration is managed by serverless.yml
Change its contents to define CRUD service.

Example serverless.yml file

service: serverless-crud

provider:
  name: aws
  runtime: nodejs4.3
  region: us-east-1
  stage: dev
  iamRoleStatements:
    - Effect: Allow
      Action:
        - dynamodb:DescribeTable
        - dynamodb:Query
        - dynamodb:Scan
        - dynamodb:GetItem
        - dynamodb:PutItem
        - dynamodb:UpdateItem
        - dynamodb:DeleteItem
      Resource: "arn:aws:dynamodb:us-east-1:*:*"

functions:
  create:
    handler: handler.create
    events:
      - http:
          path: todos
          method: post
          cors: true
  readAll:
    handler: handler.readAll
    events:
      - http:
          path: todos
          method: get
          cors: true
  readOne:
    handler: handler.readOne
    events:
      - http:
          path: todos/{id}
          method: get
          cors: true
  update:
    handler: handler.update
    events:
      - http:
          path: todos/{id}
          method: put
          cors: true
  delete:
    handler: handler.delete
    events:
      - http:
          path: todos/{id}
          method: delete
          cors: true

resources:
  Resources:
    TodosDynamoDbTable:
      Type: 'AWS::DynamoDB::Table'
      DeletionPolicy: Retain
      Properties:
        AttributeDefinitions:
          -
            AttributeName: id
            AttributeType: S
        KeySchema:
          -
            AttributeName: id
            KeyType: HASH
        ProvisionedThroughput:
          ReadCapacityUnits: 1
          WriteCapacityUnits: 1
        TableName: 'todos' 

This file define

1. Lambda function programming Language
2. Lambda function execution policy
3. Dynamodb table creation and it's policy
4. HTTP end point ( API Gateway End Point)

Then you have to define lambda function (ex. node.js) in handler.js file you can define it.

'use strict';

const todosCreate = require('./todos-create.js');
const todosReadAll = require('./todos-read-all.js');
const todosReadOne = require('./todos-read-one.js');
const todosUpdate = require('./todos-update.js');
const todosDelete = require('./todos-delete.js');

module.exports.create = (event, context, callback) => {
  todosCreate(event, (error, result) => {
    const response = {
      statusCode: 200,
      headers: {
        "Access-Control-Allow-Origin" : "*"
      },
      body: JSON.stringify(result),
    };

    context.succeed(response);
  });
};

module.exports.readAll = (event, context, callback) => {
  todosReadAll(event, (error, result) => {
    const response = {
      statusCode: 200,
      headers: {
        "Access-Control-Allow-Origin" : "*"
      },
      body: JSON.stringify(result),
    };

    context.succeed(response);
  });
};

module.exports.readOne = (event, context, callback) => {
  todosReadOne(event, (error, result) => {
    const response = {
      statusCode: 200,
      headers: {
        "Access-Control-Allow-Origin" : "*"
      },
      body: JSON.stringify(result),
    };

    context.succeed(response);
  });
};

module.exports.update = (event, context, callback) => {
  todosUpdate(event, (error, result) => {
    const response = {
      statusCode: 200,
      headers: {
        "Access-Control-Allow-Origin" : "*"
      },
      body: JSON.stringify(result),
    };

    context.succeed(response);
  });
};

module.exports.delete = (event, context, callback) => {
  todosDelete(event, (error, result) => {
    const response = {
      statusCode: 200,
      headers: {
        "Access-Control-Allow-Origin" : "*"
      },
      body: JSON.stringify(result),
    };



    context.succeed(response);
  });
};

Then you have to create new files for define your CRUD functions
Create these files

1. todos-create.js
2. todos-read-all.js
3. todos-read-one.js
4. todos-update.js
5. todos-delete.js

Then define these functions in each file.

for todos-create.js

'use strict';

const AWS = require('aws-sdk');
const dynamoDb = new AWS.DynamoDB.DocumentClient();
const uuid = require('uuid');

module.exports = (event, callback) => {
  const data = JSON.parse(event.body);

  data.id = uuid.v1();
  data.updatedAt = new Date().getTime();

  const params = {
    TableName: 'todos',
    Item: data
  };

  return dynamoDb.put(params, (error, data) => {
    if (error) {
      callback(error);
    }
    callback(error, params.Item);
  });
};

For todos-read-all.js

    'use strict';
    
    const AWS = require('aws-sdk');
    const dynamoDb = new AWS.DynamoDB.DocumentClient();
    
    module.exports = (event, callback) => {
      const params = {
        TableName: 'todos',
      };
    
      return dynamoDb.scan(params, (error, data) => {
        if (error) {
          callback(error);
        }
        callback(error, data.Items);
      });
    };


For todos-read-one.js <br>

'use strict';

const AWS = require('aws-sdk');
const dynamoDb = new AWS.DynamoDB.DocumentClient();

module.exports = (event, callback) => {
  const params = {
    TableName: 'todos',
    Key: {
      id: event.pathParameters.id
    }
  };

  return dynamoDb.get(params, (error, data) => {
    if (error) {
      callback(error);
    }
    callback(error, data.Item);
  });
};

For todos-update.js

'use strict';

const AWS = require('aws-sdk');
const dynamoDb = new AWS.DynamoDB.DocumentClient();

module.exports = (event, callback) => {
  const data = JSON.parse(event.body);

  data.id = event.pathParameters.id;
  data.updatedAt = new Date().getTime();

  const params = {
    TableName : 'todos',
    Item: data
  };

  return dynamoDb.put(params, (error, data) => {
    if (error) {
      callback(error);
    }
    callback(error, params.Item);
  });
};

For todos-delete.js

'use strict';

const AWS = require('aws-sdk');
const dynamoDb = new AWS.DynamoDB.DocumentClient();

module.exports = (event, callback) => {
  const params = {
    TableName : 'todos',
    Key: {
      id: event.pathParameters.id
    }
  };

  return dynamoDb.delete(params, (error, data) => {
    if (error) {
      callback(error);
    }
    callback(error, params.Key);
  });
};

For the run these application you need install npm dependencies

1. npm init npm initialization
2. npm install aws-sdk --save install aws-sdk
3. npm install uuid --save

Deployment
Now you can deploy these project
cd myService verify you are in project directory then you can deploy your code

serverless deploy

Use End Point
If you successfully deployed you view api gateway end pont names in your console.

Test Create End Point

curl -X POST https://XXXX.execute-api.region.amazonaws.com/dev/todos --data '{ "body" : "Learn Serverless" }'

Test for Read End Point (Read All)

curl https://XXXX.execute-api.region.amazonaws.com/dev/todos

Test for Read End Point (Read One)

curl https://XXXX.execute-api.region.amazonaws.com/dev/todos/<id>

Test for Update End Point

curl -X PUT https://XXXX.execute-api.region.amazonaws.com/dev/todos/<id> --data '{ "body" : "Understand Serverless" }'

Test for Delete End Point

`curl -X DELETE https://XXXX.execute-api.region.amazonaws.com/dev/todos/<id`>