Support Tencent Cloud COS virtual-hosted-style access (required for new buckets)

[horsley]

Context
Tencent Cloud Object Storage (COS) has deprecated path-style access for new buckets created 2024 onwards, enforcing virtual-hosted-style access.
Reference: Tencent Cloud Documentation

Problem
I attempted to add support for this in minio-go (see minio/minio-go#2191), but the maintainers rejected the PR. They stated they will not accept new provider configurations upstream and recommended that callers (downstream users like OpenCloud) should implement a custom lookup method to handle specific provider endpoints.

Request
Since OpenCloud uses minio-go, I am encountering issues connecting to new Tencent Cloud buckets due to the lack of virtual-host support.
Could you please provide a way to configure this custom lookup or update the MinIO integration to support Tencent Cloud COS?

I am willing to contribute a PR to OpenCloud to implement this if you can provide guidance on where this configuration should live.

[horsley]

I have investigated the codebase to pinpoint where this change is needed. OpenCloud uses reva for its storage backend, and the S3 blobstore implementation is where the MinIO client is initialized.

Technical Analysis:

The relevant code is in the reva repository:

• File: pkg/storage/fs/decomposeds3/blobstore/blobstore.go
• Function: New

Currently, it initializes minio.New with default options:

client, err := minio.New(u.Host, &minio.Options{
    Region: region,
    Creds:  credentials.NewStaticV4(accessKey, secretKey, ""),
    Secure: useSSL,
})

Since minio-go (v7.0.97+) relies on the BucketLookup option to handle specific provider quirks (like Tencent COS requiring virtual-hosted-style but not being auto-detected), we cannot simply update the dependency.

Proposed Solution:
We need to expose the BucketLookup configuration in the Reva config struct and pass it to the MinIO client initialization:

1. Update Config: Add a field for BucketLookup (e.g., supporting values auto, dns, path).
2. Update Initialization:

// Example mapping config string to minio constant
lookup := minio.BucketLookupAuto
if config.BucketLookup == "dns" {
   lookup = minio.BucketLookupDNS
} else if config.BucketLookup == "path" {
   lookup = minio.BucketLookupPath
}   

client, err := minio.New(u.Host, &minio.Options{
    // ... existing options ...
    BucketLookup: lookup,
})

This change should be made in the opencloud-eu/reva repository to support OpenCloud deployments on Tencent COS effectively.

[micbar]

@dragotin @aduffeck FYI