RemindMe (Backend)

Overall Architecture

This is backend of the "RemindMe" application which enables users to set, manage, and sync(WIP) reminders effortlessly using natural language input. It leverages a serverless architecture powered by AWS services, ensuring scalable, efficient, and cost-effective operations.

App in action

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Core AWS Components Used:

• AWS Lambda: Hosts the core backend logic for handling reminders, customer and device management, and scheduling tasks.
• AWS EventBridge: Manages scheduling and triggering of reminder events based on cron or rate expressions.
• AWS DynamoDB: A NoSQL database for storing reminders, customer information, and device data.
• AWS SQS: Facilitates asynchronous processing by queuing tasks between Lambda functions.
• AWS CDK: Infrastructure as code framework used to deploy and manage resources in AWS.
• Lambda Layer: Bundles shared dependencies for efficient reuse across Lambda functions.

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Project Structure

RemindMe
├── backend
│   ├── README.md                  # Backend-specific documentation
│   ├── app.py                    # Entry point for CDK application
│   ├── backend/                 # Backend source code
│   │   ├── backend_stack.py # CDK stack for backend infrastructure
│   │   ├── lambdas/         # Lambda function code
│   ├── cdk.json                 # CDK configuration file
│   ├── lambda_layer/            # Shared dependencies for Lambda
│   │   ├── requirements.txt # Dependencies for Lambda Layer
│   │   └── python/          # Lambda Layer packages
│   ├── requirements.txt         # Dependencies for Lambda functions
│   ├── requirements-dev.txt     # Development-specific dependencies
│   ├── tests/                   # Test cases for backend logic
├── README.md                        # Project documentation
├── notes.txt                        # Additional project notes
├── poc_script/                      # Proof of concept scripts

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Deployment Instructions

This guide assumes you have:

1. AWS credentials configured with access to deploy resources.
2. Node.js and npm installed.
3. Python (>=3.8) and virtualenv installed.
4. AWS CLI installed and configured.
5. CDK installed globally using npm install -g aws-cdk.

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Setup Environment Variables

Create a .env file in the root directory and populate it with the following variables:

CDK_DEFAULT_ACCOUNT=<Your AWS Account ID>
CDK_DEFAULT_REGION=<Your AWS Region>
OPENAI_API_KEY=<Your OpenAI API Key>
LAMBDA_LAYER_ARN=<ARN of the deployed Lambda Layer>
EVENTBRIDGE_TARGET=<EventBridge target ARN>
SERVICE_ACCOUNT_JSON=<JSON OF SERVICE ACCOUNT>
FIREBASE_PROJECT_ID=<FIREBASE PROJECT ID FOR SENDING PNS ON ANDROID FROM FCM.>

(More on this below)

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Install Dependencies

1. Create and activate a virtual environment:

   python3 -m venv .venv
   source .venv/bin/activate  # On Windows: .venv\Scripts\activate

2. Install development-specific dependencies (for testing and local development):

   pip install -r requirements-dev.txt

3. Install Lambda function-specific dependencies:

   pip install -r requirements.txt

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Deploy Lambda Layer

The Lambda Layer bundles shared dependencies (e.g., regex, croniter, google-auth). To deploy:

Prepare the Lambda Layer Directory

1. Create the necessary directory structure:

   mkdir -p lambda_layer/python/lib/python3.11/site-packages
   cd lambda_layer

2. Install dependencies into the site-packages directory:

   pip install --platform manylinux2014_x86_64 --only-binary=:all: --no-cache -r requirements.txt -t python/lib/python3.11/site-packages/

Package the Lambda Layer

1. Zip the contents of the python directory:

   zip -r lambda_layer.zip python

Deploy the Lambda Layer to AWS

1. Publish the Lambda layer using the AWS CLI:

   aws lambda publish-layer-version \
       --layer-name "your-layer-name" \
       --description "Lambda layer with shared dependencies" \
       --zip-file fileb://lambda_layer.zip \
       --compatible-runtimes python3.11 \
       --profile your-aws-profile

2. Note the ARN from the CLI output, which you will use in your Lambda function.

Attach the Layer to Your Lambda Function

In your AWS Lambda function code, reference the layer ARN:

set_reminder_lambda = _lambda.Function(
    self,
    "SetReminderByTextFunction",
    runtime=_lambda.Runtime.PYTHON_3_11,
    handler="set_reminder_by_text.handler",
    code=_lambda.Code.from_asset("backend/lambdas/set_reminder_by_text"),
    layers=[
        _lambda.LayerVersion.from_layer_version_arn(
            self,
            "SharedDependenciesLayer",
            "arn:aws:lambda:<region>:<account-id>:layer:your-layer-name:<version>"
        )
    ],
    environment={
        "REMINDERS_TABLE_NAME": reminders_table.table_name,
        "REMINDERS_QUEUE_ARN": reminders_queue.queue_arn,
        "REMINDERS_QUEUE_URL": reminders_queue.queue_url,
        "OPENAI_API_KEY": os.getenv("OPENAI_API_KEY"),
    },
)

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CDK Commands

The AWS CDK (Cloud Development Kit) simplifies cloud resource deployment. Below are the key commands:

1. Initialize Virtual Environment

   python3 -m venv .venv
   source .venv/bin/activate  # On Windows: .venv\Scripts\activate
   pip install -r requirements.txt

2. Synthesize CloudFormation Template This generates the CloudFormation template for your CDK application:

   cdk synth

3. List Stacks Display all stacks defined in the application:

   cdk ls

4. Deploy Stack Deploy the stack to your AWS account and region:

   cdk deploy

5. Diff Stacks Compare deployed stack with current code:

   cdk diff

6. Open Documentation Open the CDK documentation:

   cdk docs

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Notes on Requirements Files

• Root requirements-dev.txt: Contains dependencies required for development and testing (e.g., pytest, boto3).
• Root requirements.txt: Contains dependencies specific to the Lambda functions (e.g., boto3, openai).
• lambda_layer/requirements.txt: Contains dependencies that are shared across multiple Lambda functions and packaged into a Lambda Layer.

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Features

• Natural Language Parsing: Accepts user input in plain text and generates EventBridge schedules.
• Reminder Management: Stores and retrieves reminders with recurrence support.
• Device Management: [WIP] Syncs customer data across multiple devices.
• Scalability: Serverless design ensures seamless scaling.

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Dependencies

The project uses the following key dependencies:

• regex: For parsing complex reminder patterns.
• croniter: To generate cron expressions for EventBridge.

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Notes

• Environment Configuration: Ensure all environment variables are correctly set in .env.
• IAM Permissions: The AWS user deploying the stack must have permissions to create and manage Lambda, EventBridge, DynamoDB, and SQS resources.

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Contributing

1. Fork the repository.
2. Create a feature branch.
3. Commit your changes.
4. Submit a pull request.