The way to obtain Docker credentials is not compatible with Docker CLI

[l-qing]

I upgraded oras from 0.16 to 1.1 and found an incompatible change.

I expect the old format credentials to work normally as well.

The analysis is as follows:

1. Logic in oras 0.16

In oras 0.16.0, we use docker cli get credentials.

https://github.com/oras-project/oras/blob/release-0.16/internal/credential/store.go#L61C1-L62

	return &Store{
		configs: configs,
	}, nil

authConf, err := c.GetCredentialsStore(registry).Get(registry)

https://github.com/docker/cli/blob/1401f9108517b33fe38fb3acd59557dcdf4d603d/cli/config/credentials/file_store.go#L39-L81

// ConvertToHostname converts a registry url which has http|https prepended
// to just an hostname.
// Copied from github.com/docker/docker/registry.ConvertToHostname to reduce dependencies.
func ConvertToHostname(url string) string {
	stripped := url
	if strings.HasPrefix(url, "http://") {
		stripped = strings.TrimPrefix(url, "http://")
	} else if strings.HasPrefix(url, "https://") {
		stripped = strings.TrimPrefix(url, "https://")
	}

	hostName, _, _ := strings.Cut(stripped, "/")
	return hostName
}

2. Logic in oras 1.1

In oras 1.1.0, we use oras-credentials-go get credentials.

https://github.com/oras-project/oras/blob/release-1.1/internal/credential/store.go#L31-L38

import (
	credentials "github.com/oras-project/oras-credentials-go"
)

// NewStore generates a store based on the passed-in config file paths.
func NewStore(configPaths ...string) (credentials.Store, error) {
	opts := credentials.StoreOptions{AllowPlaintextPut: true}
	if len(configPaths) == 0 {
		// use default docker config file path
		return credentials.NewStoreFromDocker(opts)
	}

	var stores []credentials.Store
	for _, config := range configPaths {
		store, err := credentials.NewStore(config, opts)
		if err != nil {
			return nil, err
		}
		stores = append(stores, store)
	}
	return credentials.NewStoreWithFallbacks(stores[0], stores[1:]...), nil
}

3. actual

If such content is in my credentials, incompatible changes will occur.

{
    "auths": {
        "https://xxx.dkr.ecr.us-west-2.amazonaws.com": {
            "username": "AWS",
            "password": "",
            "auth": "",
            "email": "[email protected]"
        }
    }
}

4. expected

I can only alter the credentials into the following format for the new oras to recognize.

{
    "auths": {
        "xxx.dkr.ecr.us-west-2.amazonaws.com": {
            "username": "AWS",
            "password": "",
            "auth": "",
            "email": "[email protected]"
        }
    }
}

[l-qing]

This may be a duplicate of this issue:

• legacy docker config is not supported: legacy docker config is not supported oras#1143
• build(deps): bump github.com/oras-project/oras-credentials-go from 0.2.0 to 0.3.1 oras#1145