From 082031cc85d47cc6198c898532d233d3b022b6fd Mon Sep 17 00:00:00 2001
From: Mozi <29089388+pzhlkj6612@users.noreply.github.com>
Date: Sun, 5 Apr 2026 18:04:32 +0000
Subject: [PATCH] s3: fix TencentCOS CDN endpoint failing on bucket check
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The Global Acceleration Endpoint (cos.accelerate.myqcloud.com) of
Tencent COS does not seem to support "CreateBucket" (maybe also other
bucket management operations). Since the acceleration functionality must
be enabled per-bucket in the Tencent Cloud console, the bucket will
always exist before this endpoint is used, so this check can be safely
skipped.

Now, "no_check_bucket = true" will be auto set when using this endpoint.

Why "NewFs()": on-the-fly remotes (connection string remotes), for
example, ":s3,provider=TencentCOS,...:..." will also be fixed.

Why no unit test: I can't find a good way to test "NewFs()" without
leveraging live endpoints. I think we can extract all existing mutations
for different providers (e.g., AWS, Fastly, and Rabata) from "NewFs()"
to a new function in the future.

Some Tencent docs about this CDN endpoint:
- English: Global Acceleration Endpoint | https://www.tencentcloud.com/pt/document/product/436/40700
- Chinese: 对象存储 全球加速概述_腾讯云 | https://cloud.tencent.com/document/product/436/38866

Assisted-By: OpenCode
---
 backend/s3/s3.go   |  4 ++++
 docs/content/s3.md | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/backend/s3/s3.go b/backend/s3/s3.go
index 6c799ec18..5bfc118a9 100644
--- a/backend/s3/s3.go
+++ b/backend/s3/s3.go
@@ -1861,6 +1861,10 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 	if opt.Provider == "Rabata" {
 		f.features.Copy = nil
 	}
+	if opt.Provider == "TencentCOS" && strings.Contains(opt.Endpoint, "cos.accelerate.myqcloud.com") {
+		// Global Acceleration endpoint does not support bucket creation.
+		f.opt.NoCheckBucket = true
+	}
 	if opt.DirectoryMarkers {
 		f.features.CanHaveEmptyDirectories = true
 	}
diff --git a/docs/content/s3.md b/docs/content/s3.md
index 2ca9a8d8c..369f8866f 100644
--- a/docs/content/s3.md
+++ b/docs/content/s3.md
@@ -9119,6 +9119,16 @@ To configure access to Tencent COS, follow the steps below:
    ====                 ====
    cos                  s3
    ```
+
+#### Tencent COS Global Acceleration Endpoint
+
+When using the Global Acceleration Endpoint (`cos.accelerate.myqcloud.com`),
+rclone automatically sets `no_check_bucket = true` because this acceleration
+endpoint does not support the `CreateBucket` call which is used for ensuring
+a bucket's existence by rclone. Global Acceleration is a per-bucket feature,
+so you should first create the bucket in one physical region, then enable it
+in the Tencent Cloud console.
+
 ### US3 {#us3}
 [US3](https://www.ucloud.cn/site/product/ufile.html) Object Storage is a service that provides cloud storage for unstructured files for internet applications.