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Alex Spinov
Alex Spinov

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MinIO Has a Free API You Should Know About

#minio #storage #s3 #api

MinIO is S3-compatible object storage you can self-host — and its API is 100% compatible with AWS S3 SDKs.

S3-Compatible API

Use any AWS S3 SDK — it just works:

import { S3Client, PutObjectCommand, GetObjectCommand, ListObjectsV2Command } from '@aws-sdk/client-s3'

const s3 = new S3Client({
  endpoint: 'http://localhost:9000',
  region: 'us-east-1',
  credentials: { accessKeyId: 'minioadmin', secretAccessKey: 'minioadmin' },
  forcePathStyle: true
})

// Upload file
await s3.send(new PutObjectCommand({
  Bucket: 'my-bucket',
  Key: 'uploads/photo.jpg',
  Body: fileBuffer,
  ContentType: 'image/jpeg'
}))

// Download file
const response = await s3.send(new GetObjectCommand({
  Bucket: 'my-bucket',
  Key: 'uploads/photo.jpg'
}))

// List files
const list = await s3.send(new ListObjectsV2Command({
  Bucket: 'my-bucket',
  Prefix: 'uploads/'
}))
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Presigned URLs — Direct Upload/Download 

import { getSignedUrl } from '@aws-sdk/s3-request-presigner'

// Generate upload URL (client uploads directly to MinIO)
const uploadUrl = await getSignedUrl(s3, new PutObjectCommand({
  Bucket: 'my-bucket',
  Key: `uploads/${userId}/${filename}`
}), { expiresIn: 3600 })

// Generate download URL
const downloadUrl = await getSignedUrl(s3, new GetObjectCommand({
  Bucket: 'my-bucket',
  Key: 'uploads/report.pdf'
}), { expiresIn: 3600 })
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Event Notifications

MinIO sends events when objects change:

# Configure webhook notification
mc admin config set myminio notify_webhook:1 \
  endpoint="http://localhost:3000/api/minio-webhook" \
  queue_limit="0"

# Set bucket notification
mc event add myminio/my-bucket arn:minio:sqs::1:webhook --event put,delete
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// Handle webhook
export async function POST(request) {
  const event = await request.json()
  for (const record of event.Records) {
    console.log(`${record.eventName}: ${record.s3.object.key}`)
    if (record.eventName === 's3:ObjectCreated:Put') {
      await processUploadedFile(record.s3.object.key)
    }
  }
}
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MinIO Client SDK 

import * as Minio from 'minio'

const client = new Minio.Client({
  endPoint: 'localhost',
  port: 9000,
  useSSL: false,
  accessKey: 'minioadmin',
  secretKey: 'minioadmin'
})

// Create bucket
await client.makeBucket('backups', 'us-east-1')

// Upload with metadata
await client.putObject('backups', 'db-2024-01-01.sql.gz', fileStream, size, {
  'Content-Type': 'application/gzip',
  'X-Backup-Type': 'daily'
})

// Stream download
const stream = await client.getObject('backups', 'db-2024-01-01.sql.gz')
stream.pipe(fs.createWriteStream('./restore.sql.gz'))
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Real-World Use Case

A startup was paying $500/month for S3 storing 2TB of user uploads. They deployed MinIO on a $40/month dedicated server with 4TB NVMe. Same S3 API, same SDK, zero code changes. Annual savings: $5,520. When they needed to go multi-region, they used MinIO's built-in replication — still cheaper than S3.

MinIO is S3 without the AWS bill.

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