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https://github.com/edgelesssys/constellation.git
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5eb73706f5
* Move storage clients to separate packages * Allow setting of client credentials for AWS S3 * Use managed identity client secret or default credentials for Azure Blob Storage * Use credentials file to authorize GCS client --------- Signed-off-by: Daniel Weiße <dw@edgeless.systems>
105 lines
3.5 KiB
Go
105 lines
3.5 KiB
Go
/*
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Copyright (c) Edgeless Systems GmbH
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SPDX-License-Identifier: AGPL-3.0-only
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*/
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// Package azureblob implements a storage backend for the KMS using Azure Blob Storage.
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package azureblob
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import (
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"bytes"
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"context"
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"fmt"
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"io"
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"github.com/Azure/azure-sdk-for-go/sdk/azcore"
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"github.com/Azure/azure-sdk-for-go/sdk/azidentity"
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"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
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"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/blob"
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"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/bloberror"
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"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/container"
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"github.com/edgelesssys/constellation/v2/internal/kms/config"
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"github.com/edgelesssys/constellation/v2/internal/kms/storage"
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"github.com/edgelesssys/constellation/v2/internal/kms/uri"
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)
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type azureBlobAPI interface {
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CreateContainer(context.Context, string, *container.CreateOptions) (azblob.CreateContainerResponse, error)
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DownloadStream(context.Context, string, string, *blob.DownloadStreamOptions) (azblob.DownloadStreamResponse, error)
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UploadStream(context.Context, string, string, io.Reader, *azblob.UploadStreamOptions) (azblob.UploadStreamResponse, error)
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}
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// Storage is an implementation of the Storage interface, storing keys in the Azure Blob Store.
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type Storage struct {
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client azureBlobAPI
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container string
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}
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// New initializes a storage client using Azure's Blob Storage using the provided config.
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//
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// See the Azure docs for more information: https://azure.microsoft.com/en-us/services/storage/blobs/
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func New(ctx context.Context, cfg uri.AzureBlobConfig) (*Storage, error) {
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var creds azcore.TokenCredential
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creds, err := azidentity.NewClientSecretCredential(cfg.TenantID, cfg.ClientID, cfg.ClientSecret, nil)
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if err != nil {
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// Fallback: try to load default credentials
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creds, err = azidentity.NewDefaultAzureCredential(nil)
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if err != nil {
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return nil, fmt.Errorf("invalid client-secret credentials. Trying to load default credentials: %w", err)
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}
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}
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client, err := azblob.NewClient(fmt.Sprintf("https://%s.blob.core.windows.net/", cfg.StorageAccount), creds, nil)
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if err != nil {
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return nil, fmt.Errorf("creating storage client: %w", err)
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}
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s := &Storage{
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client: client,
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container: cfg.Container,
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}
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// Try to create a new storage container, continue if it already exists
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if err := s.createContainerOrContinue(ctx); err != nil {
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return nil, err
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}
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return s, nil
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}
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// Get returns a DEK from from Azure Blob Storage by key ID.
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func (s *Storage) Get(ctx context.Context, keyID string) ([]byte, error) {
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res, err := s.client.DownloadStream(ctx, s.container, keyID, nil)
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if err != nil {
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if bloberror.HasCode(err, bloberror.BlobNotFound) {
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return nil, storage.ErrDEKUnset
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}
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return nil, fmt.Errorf("downloading DEK from storage: %w", err)
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}
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defer res.Body.Close()
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return io.ReadAll(res.Body)
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}
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// Put saves a DEK to Azure Blob Storage by key ID.
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func (s *Storage) Put(ctx context.Context, keyID string, encDEK []byte) error {
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if _, err := s.client.UploadStream(ctx, s.container, keyID, bytes.NewReader(encDEK), nil); err != nil {
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return fmt.Errorf("uploading DEK to storage: %w", err)
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}
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return nil
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}
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// createContainerOrContinue creates a new storage container if necessary, or continues if it already exists.
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func (s *Storage) createContainerOrContinue(ctx context.Context) error {
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_, err := s.client.CreateContainer(ctx, s.container, &azblob.CreateContainerOptions{
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Metadata: config.StorageTags,
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})
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if (err == nil) || bloberror.HasCode(err, bloberror.ContainerAlreadyExists) {
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return nil
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}
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return fmt.Errorf("creating storage container: %w", err)
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}
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