aibrix throw AttributeError if the credentials is missed

[Jeffwan]

🐛 Describe the bug

I forgot setting up credentials before downloading TOS models, it throws such errors. Actually, we should improve it to ask for credentials..

root@2ecb94f62aa8:/tmp# python3 -m aibrix.downloader     --model-uri tos://aibrix-artifact-testing/models/deepseek-ai/deepseek-coder-6.7b-instruct/     --local-dir /tmp/aibrix/models_tos/
Traceback (most recent call last):
  File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/usr/local/lib/python3.8/dist-packages/aibrix/downloader/__main__.py", line 26, in <module>
    main()
  File "/usr/local/lib/python3.8/dist-packages/aibrix/downloader/__main__.py", line 22, in main
    download_model(args.model_uri, args.local_dir)
  File "/usr/local/lib/python3.8/dist-packages/aibrix/downloader/__init__.py", line 28, in download_model
    downloader = get_downloader(model_uri)
  File "/usr/local/lib/python3.8/dist-packages/aibrix/downloader/base.py", line 164, in get_downloader
    return TOSDownloader(model_uri)
  File "/usr/local/lib/python3.8/dist-packages/aibrix/downloader/tos.py", line 48, in __init__
    self.client = tos.TosClientV2(
  File "/usr/local/lib/python3.8/dist-packages/tos/clientv2.py", line 935, in __init__
    credentials_provider = StaticCredentialsProvider(ak, sk, security_token)
  File "/usr/local/lib/python3.8/dist-packages/tos/credential.py", line 111, in __init__
    self.credentials = Credentials(access_key_id, access_key_secret, security_token)
  File "/usr/local/lib/python3.8/dist-packages/tos/credential.py", line 20, in __init__
    self.access_key_id = access_key_id.strip()
AttributeError: 'NoneType' object has no attribute 'strip'

Steps to Reproduce

1. do not set credential but download a TOS model

Expected behavior

No response

Environment

No response

[brosoul]

I think this issue has already been resolved in #221 .

Did I misunderstand this issue? Can we discuss it offline.
@Jeffwan

[Jeffwan]

I think the root cause is the missing access_key_id , it should be addressed by #221. But I have side question, if we set credentials to empty string ``, does it still work for anonymous downloads? would it throw any errors? If we are not sure, we should leave a TODO and comment, otherwise, we introduce new bugs and block the anonymous artifact downloads

[brosoul]

When credentials are not set, the anonymous download of TOS has already been verified, but the anonymous download of S3 still needs to be verified.
@Jeffwan

• Verify the anonymous download of TOS
• Verify the anonymous download of S3

[Jeffwan]

Seems it does need a correct credential.

Case 1: None -> fatal error: Unable to locate credentials

Case 2: "" empty string -> 403 Forbidden

Case 3: with credential but no s3 permission

[Jeffwan]

Seems aws cli (s3) implementation is different from tos client. Most of the case we are visiting private s3 so I suggest to check the existence of AWS credential if user are using S3. @brosoul Let's do a minor change.