sendfiles.dev

sendfiles.dev allows for encrypted, browser-to-browser file transfer using WebRTC.

Architecture

sendfiles.dev has two components - a transfer metadata store and WebRTC signalling/coordination. Each component has an API Gateway, a Lambda function and a DynamoDB database.

Transfers:

• Transfers DynamoDB - stores metadata (filename, size, keys) for transfers, but not the file contents
• Transfers Lambda - simple API wrapper around Transfers DynamoDB
• Transfers API Gateway - HTTP gateway sitting in front of Transfers Lambda

Coordination:

• Sessions DynamoDB - stores API Gateway websocket IDs of file owners so receivers can request files and coordinate WebRTC
• Coord Lambda - allows sender/receiver to communicate in order to set up WebRTC connections
• Coord API Gateway - Websocket gateway sitting in front of Coord Lambda, keeping websockets open

Project Structure

backend/ - code for both Lambdas, written in Rust
frontend/ - webapp, written in React
scripts/ - misc helper scripts for build/deploy
terraform/ - config for all the infrastructure

Deployment

The Lambdas, API Gateways, DynamoDBs, IAM permissions and frontend S3 bucket/CloudFront distribution are deployed with Terraform:

Terraform

docker run -it --rm \
    -v "$(pwd)/terraform":/work/terraform \
    -w /work/terraform \
    -v "$HOME/.aws:/root/.aws" \
    -e AWS_PROFILE=sendfiles \
    -e AWS_DEFAULT_REGION=us-west-2 \
    --entrypoint sh \
    hashicorp/terraform:1.9

Backend

docker run -it --rm \
    -e CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER=/usr/bin/aarch64-linux-gnu-gcc \
    -e RUSTFLAGS="-C target-feature=+crt-static" \
    -v "$(pwd)/backend":/src \
    -w /src \
    rust:1.82 \
    bash

apt-get -qq update && apt-get -qq install -y gcc-aarch64-linux-gnu
rustup target add aarch64-unknown-linux-gnu
cargo build --target=aarch64-unknown-linux-gnu --release

./scripts/deploy-backend.sh

Frontend

Frontend assets are deployed to an S3 bucket fronted by CloudFront:

./scripts/deploy-statics.sh

Development

Running a Rust Lambda function locally is brutally difficult, so test in prod.

Running Frontend

docker run -it --rm \
    -u "$(id -u):$(id -g)" \
    -v "$(pwd)/frontend":/usr/src/app \
    -w /usr/src/app \
    -p 3000:3000 \
    node:23 \
    npm run start

Prettier

docker run -it --rm \
    -u "$(id -u):$(id -g)" \
    -v "$(pwd)/frontend":/usr/src/app \
    -w /usr/src/app \
    node:23 \
    npx [email protected] --write src

Website Design

Colors: https://coolors.co/e7e247-3d3b30-4d5061-5c80bc-e9edde

Favicon: https://favicon.io/favicon-generator/

• Font: Inconsolata
• Font Size: 90px
• Font Colour: #E9EDDE
• Background Colour: #4D5061

$ mv ~/Downloads/favicon_io.zip .
$ unzip favicon_io.zip
$ mv favicon.ico frontend/public/favicon.ico
$ mv android-chrome-192x192.png frontend/public/logo192.png
$ mv android-chrome-512x512.png frontend/public/logo512.png