WhatsApp Bot

Simple WhatsApp bot infrastructure on AWS Lambda using CDK.

Setup

uv sync

To start developing locally:

docker compose up

Create the tables:

• EVENTS_TABLE
• MESSAGES_TABLE

# events table
aws dynamodb create-table \
    --table-name 'EVENTS_TABLE' \
    --attribute-definitions \
        AttributeName=id,AttributeType=S \
        AttributeName=key,AttributeType=S \
    --key-schema \
        AttributeName=id,KeyType=HASH \
        AttributeName=key,KeyType=RANGE \
    --provisioned-throughput \
        ReadCapacityUnits=1,WriteCapacityUnits=1 \
    --endpoint-url 'http://localhost:8001'

# messages table
aws dynamodb create-table \
    --table-name 'MESSAGES_TABLE' \
    --attribute-definitions \
        AttributeName=from_,AttributeType=S \
        AttributeName=timestamp,AttributeType=S \
    --key-schema \
        AttributeName=from_,KeyType=HASH \
        AttributeName=timestamp,KeyType=RANGE \
    --provisioned-throughput \
        ReadCapacityUnits=1,WriteCapacityUnits=1 \
    --endpoint-url 'http://localhost:8001'

Run the app:

uv run uvicorn handler:app --reload

Docker

If you don't want to read:

docker compose up --build

Deployment

Deploy:

npx aws-cdk deploy --app 'uv run infra.py' --verbose
# or
make deploy

Destroy:

npx aws-cdk destroy --app 'uv run infra.py' --verbose
# or
make destroy

Redeploy:

npx aws-cdk destroy --app 'uv run infra.py' --verbose
# or
make reset

Infrastructure

Architecture Diagram

Architecture diagram of the infrastructure:

graph TD
    User --[send message]--> WhatsApp
    WhatsApp --[wbehooks]--> ApiGateway
    ApiGateway --> Lambda
    Lambda --[store chat messages]--> MessageTable
    Lambda --[store raw events]--> EventTable
    Lambda --[send message]--> WhatsApp

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Sequence diagram of the message flow:

sequenceDiagram
    User->>WhatsApp: send message
    WhatsApp->>ApiGateway: POST /
    ApiGateway->>Lambda: proxy
    Lambda->>EventTable: store raw event
    Lambda->>OpenAI: generate response
    OpenAI->>Lambda: response
    Lambda->>MessageTable: store chat message
    Lambda->>WhatsApp: send message
    WhatsApp->>User: message sent

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