Tencent COS

Engine: S3-compatible (AWS SigV4) · Preset: Tencent COS (S3-compatible)

Configuration#

Settings → Hosts → + → Tencent COS (S3-compatible).

The bucket name includes your APPID#

This is the one COS-specific gotcha. A COS bucket displayed as my-assets is actually named my-assets-1250000000, with your ten-digit APPID appended. The console shows the full name in the bucket list; use that, in full, in the Bucket field.

Region endpoints#

Create a sub-account key#

In the CAM console, not the root account:

1. Users → Create User → Custom Create, with programmatic access.
2. Save the SecretId and SecretKey.
3. Attach a custom policy scoped to the upload prefix:

{
  "version": "2.0",
  "statement": [
    {
      "effect": "allow",
      "action": ["cos:PutObject"],
      "resource": [
        "qcs::cos:ap-guangzhou:uid/1250000000:my-assets-1250000000/images/*"
      ]
    }
  ]
}

Replace the region, the uid (your APPID) and the bucket to match.

Make objects readable#

COS console → bucket → Permission Management → Public Read/Private Write for the whole bucket, or a bucket policy granting cos:GetObject to * on the prefix only. Dropline sends no ACL header, so objects inherit the bucket.

The default and CDN domains#

The default bucket domain is:

https://my-assets-1250000000.cos.ap-guangzhou.myqcloud.com

For anything with traffic, enable Domain & Transfer Management → Default CDN Acceleration Domain, or bind your own, and use that as the Public base URL.

A custom domain on a mainland-China region needs an ICP filing (备案).

The link you get back#

https://cdn.example.com/images/2026/08/19/a1f3….png

Common problems#