WriteableFileProviders.Minio 2027.1.1

WriteableFileProviders.Minio

A MinIO bucket as an IWriteableFileProvider. Part of WriteableFileProviders. It runs on AWSSDK.S3 4, the S3 protocol MinIO speaks, not on the Minio SDK.

Install

dotnet add package WriteableFileProviders.Minio

Needs .NET 10, and is native AOT compatible. Keep every WriteableFileProviders package in an app on the same major version.

Use

using WriteableFileProviders;
using WriteableFileProviders.Minio;

await using var files = new WriteableMinioFileProvider(new MinioFileProviderOptions
{
    HostAndPort = "minio.example.net:9000",
    UseSSL = true,
    AccessKey = configuration["Minio:AccessKey"],
    SecretKey = configuration["Minio:SecretKey"],
    BucketName = "files",
});

await files.UpdateFileAsync("reports/2026.csv", stream);
var url = await files.GetSignedUrlAsync("reports/2026.csv", new SignedUrlOptions { Validity = TimeSpan.FromHours(1) });

From configuration (services.AddWriteableFileProvider(section)):

{ "Files": { "Type": "WriteableMinioFileProvider", "HostAndPort": "minio.example.net:9000", "UseSSL": true,
             "AccessKey": "...", "SecretKey": "...", "BucketName": "files" } }

Or pass an IAmazonS3 you build, such as an AmazonS3Client with ServiceURL and ForcePathStyle = true. The provider never disposes it, and reads only the bucket, the root, CreateBucketIfMissing and AllowInsecureHttp from the options.

Configuration

Authentication

A MinIO key pair, or none for anonymous access, which can't presign URLs. For anything else, pass your own IAmazonS3. Nothing touches the network until the first call.

What's different

• Conditions aren't atomic. IfMatch and IfNotExists are checked by the provider first, then sent with the write. MinIO releases without conditional writes ignore them, so a concurrent change can slip in between.
• Copies and moves aren't atomic either: MinIO ignores If-None-Match on copies and If-Match on deletes, so the provider checks the destination and the source's version itself. A source changed meanwhile undoes the move.
• A file and a folder with the same name: MinIO lists only the file, and hides what's under the folder until the file is deleted.
• Writes up to 8 MiB are one request, larger ones a multipart upload (10,000 parts at most). A failed write leaves the old content. Appends rewrite the file with If-Match on the version read, and after a concurrent write read it again and append after it, up to five attempts in all.
• Listings carry no content type; GetFileInfoAsync does.
• No storage class is sent: MinIO refuses the ones it doesn't know.
• Signed URLs are presigned read and write URLs, up to 7 days, over the scheme UseSSL picks. Create URLs come from the gateway. With your own client, set AllowShorterValidity.
• A server with a site region needs Region for CreateBucketIfMissing to create a missing bucket.
• Watch throws NotSupportedException.

Learn more

• The guide: reading and writing, signed URLs, errors, providers compared.
• Moving from 2026.