Replace Supabase Storage with
Backblaze B2

# Your bucket details (save these):
BUCKET_NAME=myapp-uploads-2024
B2_ENDPOINT=s3.us-west-004.backblazeb2.com
# Full S3-compatible endpoint:
# https://s3.us-west-004.backblazeb2.com

I just created a Backblaze B2 bucket for my Next.js app. Bucket name: [YOUR_BUCKET]. Endpoint: s3.us-west-004.backblazeb2.com. Help me understand: 1) What's the difference between a private vs public bucket and which I should use for user-uploaded profile photos, 2) How CORS works on B2 and whether I need to configure it for browser uploads, 3) The difference between the native B2 API and the S3-compatible API.

# Add to .env.local:
B2_KEY_ID=your-key-id-here
B2_APP_KEY=your-application-key-here
B2_BUCKET_NAME=myapp-uploads-2024
B2_ENDPOINT=https://s3.us-west-004.backblazeb2.com
B2_REGION=us-west-004   # must match your endpoint region

I have a Backblaze B2 Application Key: keyID=[YOUR_KEY_ID] and applicationKey=[YOUR_APP_KEY]. The bucket is at endpoint s3.us-west-004.backblazeb2.com. Help me: 1) Add these to my .env.local file in the correct format for the @aws-sdk/client-s3 package, 2) Create a lib/storage.ts file with uploadFile(key, buffer, contentType), getSignedUrl(key, expiresIn), and deleteFile(key) functions using the AWS SDK v3 pointed at B2.

// lib/storage.ts
import { S3Client, PutObjectCommand, DeleteObjectCommand, GetObjectCommand } from '@aws-sdk/client-s3'
import { getSignedUrl } from '@aws-sdk/s3-request-presigner'

const s3 = new S3Client({
  region: process.env.B2_REGION!,
  endpoint: process.env.B2_ENDPOINT!,
  credentials: {
    accessKeyId: process.env.B2_KEY_ID!,
    secretAccessKey: process.env.B2_APP_KEY!,
  },
})

export async function uploadFile(key: string, buffer: Buffer, contentType: string) {
  await s3.send(new PutObjectCommand({
    Bucket: process.env.B2_BUCKET_NAME!,
    Key: key,
    Body: buffer,
    ContentType: contentType,
  }))
  return `${process.env.B2_ENDPOINT}/${process.env.B2_BUCKET_NAME}/${key}`
}

export async function getPresignedUploadUrl(key: string, contentType: string) {
  return getSignedUrl(s3, new PutObjectCommand({
    Bucket: process.env.B2_BUCKET_NAME!,
    Key: key,
    ContentType: contentType,
  }), { expiresIn: 3600 })
}

export async function getPresignedDownloadUrl(key: string) {
  return getSignedUrl(s3, new GetObjectCommand({
    Bucket: process.env.B2_BUCKET_NAME!,
    Key: key,
  }), { expiresIn: 3600 })
}

export async function deleteFile(key: string) {
  await s3.send(new DeleteObjectCommand({
    Bucket: process.env.B2_BUCKET_NAME!,
    Key: key,
  }))
}

Create a complete lib/storage.ts file for my Next.js app that uses Backblaze B2 via the AWS SDK v3 S3-compatible API. I need:
1) An S3Client configured with B2_KEY_ID, B2_APP_KEY, B2_ENDPOINT, B2_REGION env vars
2) uploadFile(key: string, buffer: Buffer, contentType: string): Promise<string> — returns the public URL
3) getPresignedUploadUrl(key: string, contentType: string, expiresIn = 3600): Promise<string> — for direct browser uploads without going through my server
4) getPresignedDownloadUrl(key: string, expiresIn = 3600): Promise<string> — for private file access
5) deleteFile(key: string): Promise<void>
Also create an API route /api/upload/presign that returns a presigned upload URL for authenticated users.

# Cloudflare DNS record:
Type: CNAME
Name: files
Target: myapp-uploads-2024.s3.us-west-004.backblazeb2.com
Proxy: ✅ (orange cloud — this enables free egress)

# Your public file URLs become:
https://files.yourdomain.com/uploads/photo.jpg

# Update .env.local:
B2_PUBLIC_URL=https://files.yourdomain.com

I want to serve my Backblaze B2 files through Cloudflare to get free egress and CDN caching. My B2 bucket endpoint is s3.us-west-004.backblazeb2.com and my bucket name is myapp-uploads-2024. My domain is yourdomain.com and it's already on Cloudflare. Help me: 1) Configure the Cloudflare CNAME for files.yourdomain.com, 2) Set up the correct Cloudflare settings (cache rules, SSL mode), 3) Update my lib/storage.ts to return files.yourdomain.com URLs instead of the B2 endpoint URL for public files.

# Migrate existing files from Supabase Storage to B2 using rclone:
# Install: brew install rclone

# Configure Supabase as source (S3-compatible):
rclone config create supabase s3 \
  provider=Other \
  endpoint=https://[project].supabase.co/storage/v1/s3 \
  access_key_id=[your-key] \
  secret_access_key=[your-secret]

# Configure B2:
rclone config create b2 b2 \
  account=[B2_KEY_ID] \
  key=[B2_APP_KEY]

# Copy everything:
rclone copy supabase:your-bucket b2:myapp-uploads-2024 --progress

I'm migrating file uploads from [Supabase Storage / Vercel Blob] to Backblaze B2. My current upload code is:

[PASTE YOUR CURRENT UPLOAD CODE HERE]

Replace it with: 1) A server-side API route that returns a presigned upload URL, 2) A client-side component that fetches the presigned URL, uploads directly to B2 (no server bandwidth cost), 3) Saves the file key/URL to my database after upload. Also show me the rclone command to migrate all existing files from my old storage to B2.