This guide explains how to set up a public read-only DuckLake on Cloudflare R2. Users can query this DuckLake through HTTPS without authentication and for free. The owner of the DuckLake pays for the storage costs but pays only a negligible amount for serving requests (see the Pricing section for more details).

The setup described here is conceptually similar to [Frozen DuckLakes]/2025/10/24/frozen-ducklake/ but it is simpler to set up.

Steps

Creating the Bucket

Create a new Cloudflare R2 bucket. Make it publicly accessible either directly or through a Cloudflare Worker.

Creating the DuckLake

Create a new DuckLake following the “Using a Remove Data Path” guide using DuckDB as the catalog database.

Uploading the DuckLake

Upload the .ducklake file and its data directory to R2. We recommend using Rclone, which has built-in support for Cloudflare R2.

rclone config

Create a new Rclone remote (see the details in the foldouts below). In our examples, we will call this your_rclone_remote.

Option Storage.
Type of storage to configure.
Choose a number from below, or type in your own value.
 1 / 1Fichier
   \ (fichier)
 2 / Akamai NetStorage
   \ (netstorage)
 3 / Alias for an existing remote
   \ (alias)
 4 / Amazon S3 Compliant Storage Providers including AWS, Alibaba, ArvanCloud, BizflyCloud, Ceph, ChinaMobile, Cloudflare, Cubbit, DigitalOcean, Dreamhost, Exaba, FileLu, FlashBlade, GCS, Hetzner, HuaweiOBS, IBMCOS, IDrive, Intercolo, IONOS, Leviia, Liara, Linode, LyveCloud, Magalu, Mega, Minio, Netease, Outscale, OVHcloud, Petabox, Qiniu, Rabata, RackCorp, Rclone, Scaleway, SeaweedFS, Selectel, Servercore, SpectraLogic, StackPath, Storj, Synology, TencentCOS, Wasabi, Zata, Other
...

Storage> 4

Option provider.
Choose your S3 provider.
Choose a number from below, or type in your own value.
Press Enter to leave empty.
 1 / Amazon Web Services (AWS) S3
   \ (AWS)
 2 / Alibaba Cloud Object Storage System (OSS) formerly Aliyun
   \ (Alibaba)
 3 / Arvan Cloud Object Storage (AOS)
   \ (ArvanCloud)
 4 / Bizfly Cloud Simple Storage
   \ (BizflyCloud)
 5 / Ceph Object Storage
   \ (Ceph)
 6 / China Mobile Ecloud Elastic Object Storage (EOS)
   \ (ChinaMobile)
 7 / Cloudflare R2 Storage
   \ (Cloudflare)
...

provider> 7

To upload your data to the R2 bucket, run:

rclone cp -v your_ducklake_catalog.ducklake your_rclone_remote:your_bucket_name/path/
rclone sync -v your_ducklake_directory your_rclone_remote:your_bucket_name/path/

Setting the CORS Policy for Browser Access (Optional)

If you try to query the dataset from another website – such as the online DuckDB shell –, you will get an error due to the CORS (Cross-Origin Resource Sharing) security mechanism:

IO Error: Failed to attach DuckLake MetaData "__ducklake_metadata_..." at path + "..."
Cannot open database "..." in read-only mode: database does not exist

or

Invalid Error: Failed to attach DuckLake MetaData "__ducklake_metadata..." at path + "..."
Opening file '...' failed with error:
NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load '...'.

To allow querying the dataset, add a CORS policy to the Cloudflare configuration of the bucket. How to do this depends on whether you are serving directly from the bucket or through a Cloudflare Worker.

If you are serving through a Cloudflare Worker, edit the code of the Worker following the “CORS header proxy” and add the following to the JavaScript code of your fetch function:

const allowedOrigins = [
  "https://duckdb.org",
  "https://shell.duckdb.org",
];

const origin = request.headers.get("Origin");

let corsOrigin = "";

if (allowedOrigins.includes(origin)) {
  corsOrigin = origin;
}
return new Response(object.body, {
  headers: {
    "Content-Type": contentType,
    "Access-Control-Allow-Origin": corsOrigin,
    "Cache-Control": "public, max-age=3600",
  }
});

If you are serving directly from the bucket, navigate to its settings and add the following CORS Policy:

[
  {
    "AllowedOrigins": [
      "https://duckdb.org",
      "https://shell.duckdb.org"
    ],
    "AllowedMethods": [
      "GET"
    ]
  }
]

For the complete Cloudflare guide on CORS policies, see the “Configure CORS” page.

Pricing

The following is an overview of the costs involved with storing a DuckLake on Cloudflare R2. As of February 2026, Cloudflare R2's pricing has the following components:

• Storage: $0.015/GB/month
• Class A operations: 1 million requests/month free, $4.50/million requests above
• Class B operations: 10 million requests/month free, $0.36/million requests above
• Egressing data: free

Serving a read-only DuckLake requires primarily Class B operations, so it should stay in the free tier even with thousands of users querying every month. For more details, please consult Cloudflare R2's “Pricing” page.