Cloudflare R2

Cloudflare documents how to create buckets, tokens and public access, and its pages are the source of truth. This page only says what this package needs. What the bucket and the keys must allow is on Storage.

Cloudflare's guides

What this package needs

• The write token: Object Read & Write, limited to the one bucket. Its Access Key ID and Secret Access Key are the publish settings.
• A public bucket: public access through the r2.dev subdomain or a custom domain. The app reads from that address.
• A private bucket: a second token with Object Read only, limited to the bucket. It ends up inside the app.
• Conditional PUT: supported. The S3 API compatibility page lists If-Match and If-None-Match under PutObject's conditional operations.

Settings

The S3 endpoint is https://<account id>.r2.cloudflarestorage.com, and the region is auto. R2 also accepts the package's default us-east-1, so PREVIEW_S3_REGION can stay unset.

Publish settings, from CI secrets or .env.local:

PREVIEW_S3_URL=https://<account id>.r2.cloudflarestorage.com/<bucket>
PREVIEW_S3_ACCESS_KEY_ID=<write token's access key id>
PREVIEW_S3_SECRET_ACCESS_KEY=<write token's secret>

The app, public bucket. The public address has no bucket in its path, which is fine for unsigned reads:

EXPO_PUBLIC_PREVIEW_S3_URL=https://pub-<id>.r2.dev

The app, private bucket:

EXPO_PUBLIC_PREVIEW_S3_URL=https://<account id>.r2.cloudflarestorage.com/<bucket>
EXPO_PUBLIC_PREVIEW_S3_READ_ACCESS_KEY_ID=<read token's access key id>
EXPO_PUBLIC_PREVIEW_S3_READ_SECRET_ACCESS_KEY=<read token's secret>
EXPO_PUBLIC_PREVIEW_S3_REGION=auto

If you publish into a folder (.../<bucket>/my-app), the public address needs the same folder: https://pub-<id>.r2.dev/my-app.

Then run a test publish.

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