Set endpoints - CoreWeave Docs

CoreWeave AI Object Storage requires virtual-hosted style URLs. Path-style addressing isn’t supported, so you must configure your client accordingly. This guide explains how to set the virtual-hosted addressing style and a valid AI Object Storage endpoint URL in your S3 configuration. In virtual-hosted style, the bucket name is part of the domain, such as https://[BUCKET-NAME].cwobject.com, instead of part of the path. When you enable this, your S3 client prepends bucket names to the endpoint in the correct format for AI Object Storage: https://[BUCKET-NAME].cwobject.com. Make sure your S3 client isn’t using path-style addressing (for example, https://cwobject.com/[BUCKET-NAME]/file). This format is unsupported and causes errors.

Use the CoreWeave fork of s5cmd with AI Object StorageThe upstream s5cmd uses path-style addressing with custom endpoint URLs. AI Object Storage doesn’t support path-style addressing and requires virtual-hosted style URLs. Use the CoreWeave fork of s5cmd, which is compatible with AI Object Storage and can safely replace any existing s5cmd installation. For setup and usage, see Migrate data to AI Object Storage.

Configure CoreWeave credentials

We recommend using a separate profile for CoreWeave AI Object Storage to avoid conflicts with your other AWS profiles and S3-compatible services. If you don’t set up this configuration, you might encounter errors when using AI Object Storage.

Configure CoreWeave credentials

Create a new credentials file and profile in your CoreWeave configuration directory.
Create a new credentials file and profile
```
AWS_SHARED_CREDENTIALS_FILE=~/.coreweave/cw.credentials aws configure --profile cw
```
When prompted, provide the following values:
- AWS Access Key ID: The Access Key ID of your CoreWeave AI Object Storage Access Key.
- AWS Secret Access Key: The Secret Key of your CoreWeave AI Object Storage Access Key.
- Default region name (Optional): To set a default region, see CoreWeave Availability Zones.
- Default output format: Use json for JSON output.
Set the default endpoint URL to the appropriate endpoint for your use case:
- The primary endpoint, https://cwobject.com, for use outside a CoreWeave cluster.
- The LOTA endpoint, http://cwlota.com, for use inside a CoreWeave cluster. The LOTA endpoint routes to the LOTA path for best performance.
Set the primary endpoint for local development
```
AWS_CONFIG_FILE=~/.coreweave/cw.config aws configure set endpoint_url https://cwobject.com --profile cw
```

Set the S3 addressing_style to virtual:

Set virtual addressing style

AWS_CONFIG_FILE=~/.coreweave/cw.config aws configure set s3.addressing_style virtual --profile cw

If you set endpoint_url and s3.addressing_style directly in your code (for example, in a Boto3 Config object), you can skip steps 3 and 4. The profile only needs the access key, secret key, and region.

Set virtual addressing style

With the AWS CLI, set the virtual addressing style for your CoreWeave profile, then verify the setting:

Configure the virtual addressing style

aws configure set s3.addressing_style virtual --profile cw

Verify the setting

aws configure get s3.addressing_style --profile cw

Boto3 shares this AWS CLI configuration, unless overridden by a Config object or the environment. This Boto3 example shows where to set the S3 addressing style within the Config object:

boto_config = Config(
    region_name = 'US-EAST-04A',
    s3={'addressing_style':'virtual'}
)

Set endpoint URL

Make sure you use valid AI Object Storage endpoint URLs:

Use the primary endpoint, https://cwobject.com, when running outside of a CoreWeave cluster.
Use the LOTA endpoint, http://cwlota.com, when running inside a CoreWeave cluster. The LOTA endpoint routes to the LOTA path for better performance.

Set the default endpoint URL in your AWS config, and verify the setting:

Set the endpoint URL

aws configure set endpoint_url "https://cwobject.com" --profile cw

Verify the endpoint URL

aws configure get endpoint_url --profile cw

Alternatively, you can set it in your Boto3 client. Set your credentials as environment variables, then pass them to the client:

export ACCESS_KEY_ID="[ACCESS-KEY-ID]"
export SECRET_ACCESS_KEY="[SECRET-ACCESS-KEY]"

import os
import boto3
from botocore.client import Config

boto_config = Config(
    region_name='US-EAST-04A',
    s3={'addressing_style': 'virtual'}
)

s3_client = boto3.client(
    's3',
    endpoint_url='https://cwobject.com',
    aws_access_key_id=os.environ['ACCESS_KEY_ID'],
    aws_secret_access_key=os.environ['SECRET_ACCESS_KEY'],
    config=boto_config
)

Full configuration examples

These configuration examples show how to set both the virtual-hosted addressing style and the AI Object Storage endpoint URL. Use one of these availability zones (AZs) for your region:

Availability Zones that support AI Object Storage

US-CENTRAL-05A
US-CENTRAL-06A
US-CENTRAL-07A
US-CENTRAL-08A
US-CENTRAL-08B

US-EAST-01A
US-EAST-02A
US-EAST-03A
US-EAST-04A
US-EAST-04B
US-EAST-06A
US-EAST-08A
US-EAST-13A
US-EAST-14A

RNO2A
US-WEST-01A
US-WEST-04A
US-WEST-09B
US-WEST-10A

CA-EAST-01A

EU-NORTH-05A

EU-SOUTH-03B
EU-SOUTH-04A

Learn more about Regions and Availability Zones.

AWS CLI
Boto3
Multi-Storage Client
s3cmd

If you use an S3 client that reads the AWS config file (~/.aws/config), such as the AWS CLI, the S3 SDKs, or s3cmd, you can add the configuration directly to your CoreWeave profile:Named profile:

[profile cw]
region = US-EAST-04A
endpoint_url = https://cwobject.com
s3 =
   addressing_style = virtual

Boto3 uses the same configuration files that you set with the AWS CLI. You can override your AWS CLI configuration by setting the addressing style in the Config object, and the endpoint_url in the client:Set your credentials as environment variables, then pass them to the client. Replace [BUCKET-NAME], [LOCAL-FILE-PATH], and [OBJECT-KEY] with your values.

export ACCESS_KEY_ID="[ACCESS-KEY-ID]"
export SECRET_ACCESS_KEY="[SECRET-ACCESS-KEY]"

import os
import boto3
from botocore.client import Config

boto_config = Config(
    region_name='US-EAST-04A',
    s3={'addressing_style': 'virtual'}
)

s3_client = boto3.client(
    's3',
    endpoint_url='https://cwobject.com',
    aws_access_key_id=os.environ['ACCESS_KEY_ID'],
    aws_secret_access_key=os.environ['SECRET_ACCESS_KEY'],
    config=boto_config
)

s3_client.upload_file('[LOCAL-FILE-PATH]', '[BUCKET-NAME]', '[OBJECT-KEY]')

See Boto3 Configuration for details.

Multi-Storage Client (MSC) wraps Boto3 with connection pool scaling, automatic multipart tuning, and a profile-based configuration system.The s3 pass-through option requires MSC version 0.43.0 or later. Configure MSC with a YAML file or a Python dictionary. The s3 option under storage_provider.options passes settings directly to botocore.config.Config, including addressing_style:

profiles:
  cw:
    storage_provider:
      type: s3
      options:
        base_path: [BUCKET-NAME]
        endpoint_url: https://cwobject.com
        region_name: [AVAILABILITY-ZONE]
        multipart_threshold: 52428800  # 50 MB
        multipart_chunksize: 52428800  # 50 MB
        s3:
          addressing_style: virtual
    credentials_provider:
      type: S3Credentials
      options:
        access_key: ${AWS-ACCESS-KEY-ID}
        secret_key: ${AWS-SECRET-ACCESS-KEY}

When running inside a CoreWeave cluster, set endpoint_url to http://cwlota.com to use the LOTA cache.See the Multi-Storage Client documentation for installation, Python dictionary configuration, and the full reference.

~/.s3cfg file

# ~/.s3cfg
host_base = cwlota.com
host_bucket = %(bucket)s.cwlota.com
use_https = False

​Configure CoreWeave credentials

​Set virtual addressing style

​Set endpoint URL

​Full configuration examples

Configure CoreWeave credentials

Set virtual addressing style

Set endpoint URL

Full configuration examples