s3: add IBM IAM signer - fixes #7617

backend/s3/ibm_signer.go

@@ -0,0 +1,59 @@
+package s3
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"github.com/IBM/go-sdk-core/v5/core"
+	"github.com/aws/aws-sdk-go-v2/aws"
+	v4signer "github.com/aws/aws-sdk-go-v2/aws/signer/v4"
+)
+
+// Authenticator defines an interface for obtaining an IAM token.
+type Authenticator interface {
+	GetToken() (string, error)
+}
+
+// IbmIamSigner is a structure for signing requests using IBM IAM.
+// Requeres APIKey and Resource InstanceID
+type IbmIamSigner struct {
+	APIKey     string
+	InstanceID string
+	Auth       Authenticator
+}
+
+// SignHTTP signs requests using IBM IAM token.
+func (signer *IbmIamSigner) SignHTTP(ctx context.Context, credentials aws.Credentials, req *http.Request, payloadHash string, service string, region string, signingTime time.Time, optFns ...func(*v4signer.SignerOptions)) error {
+	var authenticator Authenticator
+	if signer.Auth != nil {
+		authenticator = signer.Auth
+	} else {
+		authenticator = &core.IamAuthenticator{ApiKey: signer.APIKey}
+	}
+	token, err := authenticator.GetToken()
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Authorization", "Bearer "+token)
+	req.Header.Set("ibm-service-instance-id", signer.InstanceID)
+	return nil
+}
+
+// NoOpCredentialsProvider is needed since S3 SDK requires having credentials, eventhough authentication is happening via IBM IAM.
+type NoOpCredentialsProvider struct{}
+
+// Retrieve returns mock credentials for the NoOpCredentialsProvider.
+func (n *NoOpCredentialsProvider) Retrieve(ctx context.Context) (aws.Credentials, error) {
+	return aws.Credentials{
+		AccessKeyID:     "NoOpAccessKey",
+		SecretAccessKey: "NoOpSecretKey",
+		SessionToken:    "",
+		Source:          "NoOpCredentialsProvider",
+	}, nil
+}
+
+// IsExpired always returns false
+func (n *NoOpCredentialsProvider) IsExpired() bool {
+	return false
+}