[Feature Request] barman-cloud plugin should support virtual-hosted style addressing for S3-compatible storage

[buddyGH]

Description:

I'm using CloudNativePG with the barman-cloud plugin (version 0.9.0) for PostgreSQL backups to Alibaba Cloud OSS. However, I've encountered a critical issue: the plugin only supports path-style addressing, while Alibaba Cloud OSS (and many other S3-compatible services) now require virtual-hosted style addressing.

Problem Details:

AWS has deprecated path-style addressing since September 30, 2023
Many cloud providers (Alibaba Cloud OSS, Google Cloud Storage, etc.) require or strongly recommend virtual-hosted style
The barman-cloud plugin doesn't provide any configuration parameter for addressing_style
When endpointURL is specified, it defaults to path-style addressing

Current Workaround:

Currently, users have to:

Use custom backup solutions instead of the official plugin
Or use unsupported path-style endpoints (if available)

Expected Behavior:

The barman-cloud plugin should support both addressing styles with a configuration parameter like:

configuration:
  destinationPath: "s3://bucket-name/"
  endpointURL: "https://bucket-name.oss-cn-region.aliyuncs.com"
  s3AddressingStyle: "virtual"  # or "path"

Or automatically detect the appropriate style based on the endpoint URL format.

Technical Background:

• AWS SDK (boto3) already supports addressing_style parameter in boto3.session.Config

• Virtual-hosted style is now the standard for S3-compatible services

• Path-style addressing has been deprecated by AWS

Impact:

This limitation prevents users from using the official plugin with:

• Alibaba Cloud OSS

• Google Cloud Storage

• DigitalOcean Spaces

• And other S3-compatible services that enforce virtual-hosted style

Proposed Solution:

Add a new parameter s3AddressingStyle to the ObjectStore configuration that gets passed to the underlying boto3 client configuration.

Code Reference:

In barman-cloud implementation, it should configure boto3 like:

config = boto3.session.Config(
    s3={'addressing_style': addressing_style}
)
s3_client = boto3.client(
    's3',
    endpoint_url=endpoint,
    config=config
)

Environment:

• CloudNativePG: 1.28.0

• barman-cloud plugin: 0.9.0

• Kubernetes: 1.32.7

• Storage: Alibaba Cloud OSS

Additional Context:

1. Attempted Solutions:

[ ] I have tried setting the environment variable AWS_S3_ADDRESSING_STYLE=virtual in the pod configuration, but it has no effect

• Tested various endpointURL formats including:

  • https://bucket-name.oss-cn-region.aliyuncs.com (virtual-hosted style)

  • https://oss-cn-region.aliyuncs.com (path-style)

• The plugin consistently uses path-style addressing regardless of the endpoint URL format

2. Current Status:

• Alibaba Cloud OSS strictly enforces virtual-hosted style addressing

• AWS has completely phased out path-style support

• This issue is becoming critical as more S3-compatible services adopt virtual-hosted style

3. Reproduction Steps:

• Configure barman-cloud plugin with Alibaba Cloud OSS endpoint

• Set endpointURL to virtual-hosted style format

• Observe that the plugin still attempts path-style requests

• Receive errors from OSS indicating path-style is not supported

4. Workaround Limitations:

• Custom backup scripts lack the integration and reliability of the official plugin

• Alternative S3-compatible endpoints may not be available in all regions

• This forces users to choose between functionality and using the official tooling

[martinmarques]

Hi,

I believe this PR would address the feature you are asking for here. Could you confirm that?