Serverless architecture for Java developers

2. Typical Serverless Architecture
Copyright © 2016 classicprogrammerpaintings.com All Rights Reserved.

3. Agenda
• Frontend
• Add security with Cognito and Google Identity
Provider
• Store Data in Dynamo DB
• Build Microservice with Lambda
• Deploy source code into S3 Bucket

4. Frontend
https://www.thoughtworks.com/radar/languages-and-frameworks

5. Add security with Cognito and Google Identity Provider
1. Obtain Google IDP Client Id:
2. Update index.html with Google Client Id
3. Update Identity Pool config.json with Google
Client Id
4. Create a new Identity Pool
5. Update javascript config file(s) with
Identity Pool Id

6. variable "login_provider" {
default = "105303240909-am1nkfpr1fmo9d2bce5pbkv.apps.googleusercontent.com"
}
resource "template_file" "login_provider_config" {
template = "${file("${path.module}/../conf/cognito/config.json.tpl")}"
vars {
login_provider = "${var.login_provider}"
}
provisioner "local-exec" {
command ="echo "${self.rendered}" >
${path.module}/../conf/cognito/config.json"
}
}

7. Store Data in DynamoDB
saveAnswer: function(problemId, answer) {
return cognito.identity.then(function(identity) {
var db = new AWS.DynamoDB.DocumentClient();
var item = {
TableName: 'answers',
Item: {
userId: identity.id,
problemId: problemId,
answer: answer
}
};
return cognito.sendAwsRequest(db.put(item), function(){
return saveAnswer(problemId, answer);
})
})
}

8. {
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"Action": [
"dynamodb:BatchGetItem",
"dynamodb:BatchWriteItem",
"dynaeleteItem",
"dynamodb:modb:DGetItem",
"dynamodb:PutItem",
"dynamodb:Query",
"dynamodb:UpdateItem"
],
"Resource": ["arn:aws:dynamodb:us-east-1:1111111111:table/problems"],
"Condition": {
"ForAllValues:StringEquals": {
"dynamodb:LeadingKeys": ["${cognito-identity.amazonaws.com:sub}"]}
}
}]
}
IAM Permission Policy

9. Build Microservice with Lambda
Frontend code
checkAnswer: function(problemId, answer) {
return cognito.identity.then(function(identity) {
var lambda = new AWS.Lambda();
var params = {
FunctionName: 'spa_checkAnswer',
Payload: JSON.stringify({ problemId: problemId, answer: answer })
};
return cognito.sendAwsRequest(lambda.invoke(params), function(){
return checkAnswer(problemId, answer);
})
})
}

10. Build Microservice with Lambda
Backend code
'use strict';
let doc = require('dynamodb-doc');
let dynamo = new doc.DynamoDB();
exports.handler = (event, context, callback) => {
let params = {
TableName : "problems",
KeyConditionExpression: "problemId = :problemId",
ExpressionAttributeValues: {
":problemId":event.problemId
}
};
dynamo.query(params, function(err, data) {
if (err) {
callback(Error("Unable to query: " + JSON.stringify(event) + " .Error:" +
JSON.stringify(err)));
} else {
if (data.Items.length > 0) {
let test = data.Items[0].Code.replace('__', event.answer) + '; problem();';
context.succeed(eval(test));
} else {
callback(Error("Problem not found"));
}
}
});
};

11. API Gateway
Copyright © 2016 Amazon Web Services All Rights Reserved.

12. Swagger definition
{
"swagger":
...
"paths":
{
"/get-tenants": {
"get": {
"responses": {
"200": {
"description": "List of tenants",
"schema": {"$ref": "#/definitions/Tenants" }
}}
"x-amazon-apigateway-integration": {
"type": "aws",
"uri": "arn:aws:apigateway:us-east-1:lambda:path/2015-03-
31/functions/arn:aws:lambda:us-east-
1:111111111111:function:${func}/invocations",
"httpMethod": "POST",
"credentials":"arn:aws:iam::111111111111:role/${invoke-lambda}",
...

13. First Deployment
1. Deploy infrastructure
$ terraform apply
2. Deploy the content to s3 bucket
$ npm install
$ aws s3 sync app/ s3://s3-spa.demos3.com/ --acl public-read --profile spa
3. Import DynamoDB data
$ aws dynamodb batch-write-item --request-items file://conf/dynamodb/sampledata/Problems.json --profile spa
4. Enjoy http://s3-spa.demos3.com.s3-website-us-east-1.amazonaws.com

14. Alternatives
• Cloud Formation (CF stack)
• Boto3
• Troposphere

15. References
• Serverless Single Page Apps – Ben Rady
• AWS Lambda in Action - Danilo Poccia
• https://aws.amazon.com/documentation/
• https://www.terraform.io/
• https://github.com/yegor86/spa-aws

16. Questions