How to Migrate Your App to Cloud using Serverless: Complete Guide
By Braincuber Team
Published on April 16, 2026
What You'll Learn:
- What serverless architecture is and its benefits for cloud migration
- How to start migrating with simple APIs using AWS Lambda and API Gateway
- How to migrate databases to DynamoDB with auto-scaling capabilities
- How to create connected APIs that access DynamoDB using the AWS SDK
- How to set up cloud storage with Amazon S3 buckets
- How to host and deploy static websites serverlessly on S3 with Route 53
You have got an app that you run and you have heard loads about serverless and the benefits. You may have even tried deploying some things with serverless but you want to move your whole app to serverless. How do you do that? This complete tutorial will guide you through the steps you can take to migrate your app or service to the cloud with Serverless. This step by step guide is designed as a beginner guide to serverless architecture, helping you understand how to leverage AWS services for a successful cloud migration.
Understanding Serverless Architecture
Serverless architecture allows you to build and run applications without thinking about servers. With AWS Lambda, you can run code functions and only pay for when the function is running. You can write your code in Ruby, Python, Node, Java, Go, or .Net and through the AWS SDK you can easily access other AWS services such as email, SMS, Kinesis, and databases.
Pay Per Execution
Only pay for the compute time you consume. No charge when your code is not running, reducing costs significantly.
Automatic Scaling
AWS automatically scales your functions in response to incoming requests, handling any load without configuration.
No Server Management
There is no need to provision or maintain any servers. AWS handles the infrastructure entirely.
High Availability
Built-in redundancy and fault tolerance across multiple availability zones without additional configuration.
The Migration Strategy
When you start the process of migrating your service to serverless, it is best to start with the low hanging fruit. This will get you some experience working with serverless and AWS while still providing value to the application.
| Migration Phase | AWS Services | Complexity |
|---|---|---|
| Phase 1: Simple APIs | Lambda, API Gateway | Low |
| Phase 2: Databases | DynamoDB | Medium |
| Phase 3: Connected APIs | Lambda, DynamoDB SDK | Medium |
| Phase 4: Storage | S3, serverless-s3-sync | Low |
| Phase 5: Website Hosting | S3, Route 53 | Medium |
Phase 1: Migrating Simple APIs
Simple APIs are endpoints that do not need to access your databases to perform their actions. This could be an API for sending emails, hitting external APIs and combining the data, or for running some logic on the input. A secondary advantage to creating these APIs is that they reduce the load on your existing servers. This removal of functionality and complexity has allowed many companies to reduce the code on their servers by over 50%.
Creating Your First Lambda Function
To create an API using AWS Lambda and API Gateway, you need to write a function that executes the logic. Then you need to export the function as exports.handler. Here is the basic structure of a Lambda handler function:
exports.handler = async (event, context) => {
// your function code goes here
return {
statusCode: 200,
body: JSON.stringify({ message: 'Hello from Lambda!' })
};
};
Configuring the Serverless Framework
To deploy your code with an API using serverless, you need to add your new function to the serverless.yml file under the function declaration. Define the location of the code as well as the methods and path for the API endpoint.
functions:
myFirstApi:
handler: src/myFirstApi/index.handler
events:
- http:
path: getFromMyAPI
method: GET
cors: true
This will deploy your function code to a URL provided by AWS API Gateway. If you want to create a more readable API address, you can use Route 53 to forward traffic.
Pro Tip: Start Small
Begin your serverless journey with simple APIs that do not require database access. This builds confidence and understanding before tackling more complex migrations.
Phase 2: Migrating Databases to DynamoDB
Databases are obviously a massive part of any software product. With serverless, you can use DynamoDB where scaling and performance are managed by AWS, leaving you to work on the valuable parts of the product.
Creating DynamoDB Tables in Serverless
Creating DynamoDB tables in serverless is relatively simple. All you need to do is create a new Resource and provide the table details:
Resources:
OrderTable:
Type: AWS::DynamoDB::Table
Properties:
TableName: order-table
AttributeDefinitions:
- AttributeName: userID
AttributeType: S
- AttributeName: orderId
AttributeType: S
KeySchema:
- AttributeName: userId
KeyType: HASH
- AttributeName: orderId
KeyType: RANGE
Configuring Auto-Scaling for DynamoDB
To get auto-scaling added to your table, you have two options: PayPerRequest billing or provision auto-scaling on the table.
| Billing Mode | Best For | Configuration |
|---|---|---|
| PAY_PER_REQUEST | Irregular traffic with spikes and troughs | Simpler - just add BillingMode property |
| Provisioned with Auto-Scaling | Predictable, steady traffic patterns | Requires serverless-dynamodb-autoscaling plugin |
PayPerRequest is better if you have more irregular traffic that comes in spikes and troughs. To provision it, replace ProvisionedThroughput lines with this line:
BillingMode: PAY_PER_REQUEST
For provisioned capacity with auto-scaling, you can use the serverless-dynamodb-autoscaling plugin. To install it:
npm install serverless-dynamodb-autoscaling
Data Migration Tip
When migrating existing data to DynamoDB, AWS provides excellent migration guides for MongoDB, Cassandra, MySQL, and RDBMS databases.
Phase 3: Creating Connected APIs
Now that you have your databases created, you should be able to convert most of your remaining APIs over to serverless. These might be user lookups, logins, product lookups, order status updates, or any other kind of request that reads or writes to one of your tables.
Accessing DynamoDB with the AWS SDK
To access your data in DynamoDB, you can use the AWS SDK and the DynamoDB document client. This interface has the functionality to perform all the REST methods as well as a few extras such as scan, query, batchGet, and batchWrite.
Here is an example of a simplified method for getting data from DynamoDB:
get(ID, table) {
if (!table) throw 'table needed';
return new Promise((resolve, reject) => {
let params = {
TableName: table,
Key: { ID: ID },
};
documentClient.get(params, function (err, data) {
if (err) {
return reject(err);
}
return resolve(data.Item);
});
});
}
With these methods, you should be able to port almost all your APIs over to serverless. This can be a large piece of work, but there are many benefits including autoscaling, only pay for what you use, redundancy, and separation of concerns.
Start with Simple APIs
Begin by migrating APIs that do not need database access. This builds experience and reduces load on existing servers immediately.
Create DynamoDB Tables
Set up your DynamoDB resources with proper auto-scaling configuration. Choose between PayPerRequest and provisioned capacity.
Build Connected APIs
Create helper classes for database operations. Migrate read/write APIs that connect to your new DynamoDB tables.
Phase 4: Cloud Storage with Amazon S3
Cloud storage was the first service that was ever provided by AWS: Amazon S3. This service allows you to host files in the cloud, define the access policies, and easily use those files in other AWS services. Items stored in S3 are put into buckets, which are isolated containers used to group items.
Creating S3 Buckets in Serverless
To create a bucket in serverless, you are defining a new resource. One thing to remember is that the bucket name must be globally unique:
resources:
Resources:
UploadBucket:
Type: AWS::S3::Bucket
Properties:
BucketName: my-bucket-name-is-unique
Auto-Sync Local Files to S3
To automatically upload files to your new bucket, you can use the serverless-s3-sync plugin. Install it and add it to your serverless file:
npm install --save serverless-s3-sync
Phase 5: Serverless Website Hosting
So far you will have had to make quite a few URL changes to your website for all the API changes that you have already implemented. Now would not it be cool if you could also host that website entirely serverlessly?
Configuring Website Hosting on S3
You need to add a few more things onto your S3 bucket configuration. You need to set the access control and tell S3 that this is a website you are hosting in the bucket:
MyWebsiteBucket:
Type: AWS::S3::Bucket
Properties:
BucketName: example.com
WebsiteConfiguration:
IndexDocument: index.html
AccessControl: PublicRead
Configuring Route 53 DNS
Now you can view your site at the S3 website endpoint. But it would be better if you were hosting on your own URL. We need to create a DNS record that points the requested domain to our S3 bucket. In Route 53, make sure you have set up your hosted zone name, and then you can add the DNS record.
With all set up, run sls deploy to add the DNS record to your account, and now you can visit your domain and see the live page hosted from S3.
Benefits of Serverless Migration
After completing your serverless migration, you will experience numerous benefits that make the effort worthwhile.
Cost Optimization
Pay only for what you use with no idle server costs. Many applications see 50-70% cost reduction after migration.
Automatic Scaling
Handle traffic spikes without provisioning additional servers. AWS automatically scales your functions to meet demand.
Built-in Reliability
AWS Lambda runs across multiple availability zones automatically, providing high availability without extra configuration.
Faster Development
Focus on business logic instead of infrastructure. Deploy new features in minutes instead of days or weeks.
Frequently Asked Questions
What is the best approach to migrate to serverless?
Start with simple APIs that do not require database access. This builds experience with Lambda and API Gateway while providing immediate value by reducing load on existing servers.
How do I handle database connections in serverless?
Use DynamoDB for fully managed, serverless database operations. For traditional databases, implement connection pooling and reuse connections across Lambda invocations.
What are the cost implications of serverless migration?
Serverless uses pay-per-execution pricing, meaning you only pay when your code runs. This typically results in 50-70% cost savings for applications with variable traffic.
How do I deploy and manage serverless applications?
Use the Serverless Framework which provides a unified toolchain for defining, deploying, and managing AWS Lambda functions and related resources.
Can I host a complete website on S3 serverlessly?
Yes, you can host static websites entirely on S3 with static content, and use Lambda for dynamic API endpoints. Route 53 can route traffic to your S3 bucket.
Need Help with Cloud Migration?
Our experts can help you migrate your application to serverless architecture on AWS. Get a free consultation to discuss your cloud migration strategy.