File Upload Service (Go)

A small service that handles image uploads for an imaginary chat application: it stores encrypted files, creates a resized original + a preview image, and records upload metadata for later retrieval.

Inspired by Code Aesthetic’s “file upload service” walkthrough (the video uses TypeScript; this project is the Go implementation).

Features

• Upload images over HTTP
• Resize originals (max width) + generate preview images
• Encrypt stored files (AES-GCM)
• Record metadata in SQLite for later downloads
• Support for local filesystem or S3-compatible storage backends

Quickstart

Requirements

• Go 1.21+
• A C toolchain (required by github.com/mattn/go-sqlite3)

Run the server

make server

The server listens on http://localhost:1323 and writes:

• Metadata: filer.sqlite
• Encrypted files: temp/<upload-uuid>/... (local storage) or S3 bucket (S3 storage)
• Working files: vault/<vault-uuid>/... (temporary staging area)

Storage Backend: By default, files are stored locally. To use S3-compatible storage (e.g., MinIO), set UPLOADER_STORAGE=s3 and configure the S3 options. See docs/LOCAL_S3.md for details.

Upload a file

The API requires an key header. It must be 32 characters (AES-256 key material) and pass validation.

KEY='0123456789abcdef0123456789abcdef'
curl -sS \
  -H "key: ${KEY}" \
  -F "file=@./path/to/image.png" \
  http://localhost:1323/file/upload

Response shape:

{
  "file_name": "example.png",
  "preview_url": "http://localhost:1323/file/<uid>?preview=true",
  "download_url": "http://localhost:1323/file/<uid>",
  "uploaded_at": "2025-01-01T00:00:00Z"
}

Download an original or preview

UID='<uid-from-upload-response>'
curl -sS -H "key: ${KEY}" "http://localhost:1323/file/${UID}" -o original.bin
curl -sS -H "key: ${KEY}" "http://localhost:1323/file/${UID}?preview=true" -o preview.bin

API

• POST /file/upload (multipart form field: file)
• GET /file/:uid (query: preview=true|false)

More details: docs/API.md. Local S3 setup (MinIO): docs/LOCAL_S3.md.

Project layout

• Root package: interfaces and core types (uploader.*)
• internal/http: Echo server + handlers
• internal/storage: storage backends (local filesystem and S3-compatible)
• internal/encryption: AES-GCM encryption provider
• internal/scaler + internal/preview: image scaling + preview generation
• internal/db: SQLite-backed filer (metadata store)

Architecture notes: docs/ARCHITECTURE.md.

Developer commands

make test
make fmt
make ci

Notes / assumptions

• This service assumes authentication/authorization is handled elsewhere; the encryption key is provided per-request.
• Only common image types are supported today (image/png, image/jpeg, image/gif).

Roadmap

• Finish CLI (cmd/cli)
• Add S3 storage backend
• Improve error responses + consistent JSON errors
• Streaming encryption (avoid buffering whole files in memory)