Tencent Cloud COS (Object Storage)

Manage Tencent Cloud COS buckets and objects via the official cos-python-sdk-v5 client.

Setup: See tencentcloud authentication for SecretId / SecretKey / region setup. The SDK reads TENCENTCLOUD_SECRET_ID / TENCENTCLOUD_SECRET_KEY / TENCENTCLOUD_REGION from the environment.

CLI (preferred)

The skill ships scripts/cos.py — a self-contained CLI that wraps every COS operation below. Prefer this over hand-rolled SDK calls when the user's request maps cleanly onto one of its subcommands; it's what the maintained code paths exercise.

COS=$SKILL_DIR/scripts/cos.py

python3 $COS buckets                                  # list all buckets
python3 $COS ls mydata-1250000000 --prefix images/    # list objects
python3 $COS upload mydata-1250000000 ./report.pdf --key docs/report-2026.pdf
python3 $COS download mydata-1250000000 docs/report-2026.pdf --output ./out.pdf
python3 $COS url mydata-1250000000 docs/report-2026.pdf --expires 3600
python3 $COS du mydata-1250000000 --prefix logs/
python3 $COS cp mydata-1250000000 old/path.txt new/path.txt
python3 $COS batch-delete mydata-1250000000 --prefix temp/old/ --dry-run
python3 $COS batch-delete mydata-1250000000 --prefix temp/old/   # actually delete
python3 $COS info mydata-1250000000 docs/report-2026.pdf

Run python3 $COS --help (or python3 $COS <cmd> --help) for full flags. Pass --region <region> to override per-call.

When to Use

• List COS buckets across the account
• List objects in a bucket (with prefix / delimiter filtering)
• Upload / download files
• Delete a single object or batch-delete by prefix
• Generate pre-signed download URLs (private bucket sharing)
• Calculate bucket / prefix storage usage
• Copy objects within a bucket

Dependencies

pip install cos-python-sdk-v5

Bucket naming

Tencent Cloud bucket names always end in -<APPID>, e.g. mydata-1250000000. The APPID is the numeric account identifier. The SDK requires the full name-APPID form everywhere a bucket is named.

Quick start

import os
from qcloud_cos import CosConfig, CosS3Client

config = CosConfig(
    Region=os.environ["TENCENTCLOUD_REGION"],
    SecretId=os.environ["TENCENTCLOUD_SECRET_ID"],
    SecretKey=os.environ["TENCENTCLOUD_SECRET_KEY"],
    Scheme="https",
)
client = CosS3Client(config)

Workflows

List all buckets

resp = client.list_buckets()
for b in resp["Buckets"]["Bucket"]:
    print(b["Name"], b["Location"], b["CreationDate"])

List objects in a bucket

# Single page (max 1000 objects)
resp = client.list_objects(Bucket="mydata-1250000000", Prefix="images/", Delimiter="/")
for obj in resp.get("Contents", []):
    print(obj["Key"], int(obj["Size"]), obj["LastModified"])

# Paginate through everything
marker = ""
while True:
    resp = client.list_objects(Bucket="mydata-1250000000", Prefix="logs/", Marker=marker, MaxKeys=1000)
    for obj in resp.get("Contents", []):
        print(obj["Key"])
    if resp.get("IsTruncated") != "true":
        break
    marker = resp["NextMarker"]

Upload a file

# Streaming upload — handles multipart / resumes / 5GB+ files transparently
client.upload_file(
    Bucket="mydata-1250000000",
    Key="uploads/2026/report.pdf",
    LocalFilePath="./report.pdf",
)

Download a file

client.download_file(
    Bucket="mydata-1250000000",
    Key="uploads/2026/report.pdf",
    DestFilePath="./report.pdf",
)

Generate a pre-signed download URL

# Default expiry 1 hour; pass Expired=86400 for 24h, etc.
url = client.get_presigned_url(
    Method="GET",
    Bucket="mydata-1250000000",
    Key="uploads/2026/report.pdf",
    Expired=3600,
)
print(url)

Delete a single object

client.delete_object(Bucket="mydata-1250000000", Key="uploads/old-file.txt")

Batch delete by prefix (with dry-run safety)

# 1) Always preview first
to_delete = []
marker = ""
while True:
    resp = client.list_objects(Bucket="mydata-1250000000", Prefix="temp/old/", Marker=marker, MaxKeys=1000)
    for obj in resp.get("Contents", []):
        to_delete.append({"Key": obj["Key"]})
    if resp.get("IsTruncated") != "true":
        break
    marker = resp["NextMarker"]

print(f"Would delete {len(to_delete)} objects")
for o in to_delete[:10]:
    print("  -", o["Key"])

# 2) Confirm with the user before running this:
# resp = client.delete_objects(Bucket="mydata-1250000000", Delete={"Object": to_delete, "Quiet": "false"})
# print("Deleted:", len(resp.get("Deleted", [])))

Calculate bucket / prefix size (du)

total_bytes = 0
total_count = 0
marker = ""
while True:
    resp = client.list_objects(Bucket="mydata-1250000000", Prefix="logs/", Marker=marker, MaxKeys=1000)
    for obj in resp.get("Contents", []):
        total_bytes += int(obj["Size"])
        total_count += 1
    if resp.get("IsTruncated") != "true":
        break
    marker = resp["NextMarker"]

print(f"{total_count} objects, {total_bytes / 1024 / 1024:.1f} MiB")

Copy objects within a bucket

client.copy_object(
    Bucket="mydata-1250000000",
    Key="new/path.txt",
    CopySource={
        "Bucket": "mydata-1250000000",
        "Key": "old/path.txt",
        "Region": os.environ["TENCENTCLOUD_REGION"],
    },
)

Safety reminders

• Confirm batch deletes with the user before running. The delete_objects call is irreversible — there's no recycle bin in COS by default.
• Pre-signed URLs are bearer tokens — anyone with the URL gets the object until it expires. Default to short expiries (1 hour) unless the user explicitly asks for longer.
• Cross-region operations require the source / destination Region in CopySource. Mismatched region triggers NoSuchBucket.
• download_file overwrites the destination without asking. Pick DestFilePath carefully when scripting in a loop.

Error patterns

Symptom	Likely cause
NoSuchBucket	Wrong region, wrong APPID suffix on the bucket name
AccessDenied	Sub-account missing QcloudCOSReadOnlyAccess / QcloudCOSDataReadOnly etc.
SignatureDoesNotMatch	SecretKey was pasted with leading / trailing whitespace, or the system clock is off by more than 5 minutes
RequestTimeTooSkewed	Same — clock skew

Console links

• COS console: https://console.cloud.tencent.com/cos/bucket
• API reference: https://www.tencentcloud.com/document/product/436/41330