constellation/internal/kms/storage/azurestorage.go
Otto Bittner 0e71322e2e keyservice: move kms code to internal/kms
Recovery (disk-mapper) and init (bootstrapper)
will have to work with multiple external KMSes
in the future.
2023-01-19 13:14:55 +01:00

106 lines
3.6 KiB
Go

/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
package storage
import (
"bytes"
"context"
"fmt"
"io"
"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/blob"
"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/bloberror"
"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/container"
"github.com/edgelesssys/constellation/v2/internal/kms/config"
)
type azureBlobAPI interface {
CreateContainer(context.Context, string, *container.CreateOptions) (azblob.CreateContainerResponse, error)
DownloadStream(context.Context, string, string, *blob.DownloadStreamOptions) (azblob.DownloadStreamResponse, error)
UploadStream(context.Context, string, string, io.Reader, *azblob.UploadStreamOptions) (azblob.UploadStreamResponse, error)
}
// AzureStorage is an implementation of the Storage interface, storing keys in the Azure Blob Store.
type AzureStorage struct {
client azureBlobAPI
connectionString string
containerName string
opts *AzureOpts
}
// AzureOpts are additional options to be used when interacting with the Azure API.
type AzureOpts struct {
service *azblob.ClientOptions
download *azblob.DownloadStreamOptions
upload *azblob.UploadStreamOptions
}
// NewAzureStorage initializes a storage client using Azure's Blob Storage: https://azure.microsoft.com/en-us/services/storage/blobs/
//
// A connections string is required to connect to the Storage Account, see https://docs.microsoft.com/en-us/azure/storage/common/storage-configure-connection-string
// If the container does not exists, a new one is created automatically.
// Connect options for the Client, Downloader and Uploader can be configured using opts.
func NewAzureStorage(ctx context.Context, connectionString, containerName string, opts *AzureOpts) (*AzureStorage, error) {
if opts == nil {
opts = &AzureOpts{}
}
client, err := azblob.NewClientFromConnectionString(connectionString, opts.service)
if err != nil {
return nil, fmt.Errorf("creating storage client from connection string: %w", err)
}
s := &AzureStorage{
client: client,
connectionString: connectionString,
containerName: containerName,
opts: opts,
}
// Try to create a new storage container, continue if it already exists
if err := s.createContainerOrContinue(ctx); err != nil {
return nil, err
}
return s, nil
}
// Get returns a DEK from from Azure Blob Storage by key ID.
func (s *AzureStorage) Get(ctx context.Context, keyID string) ([]byte, error) {
res, err := s.client.DownloadStream(ctx, s.containerName, keyID, s.opts.download)
if err != nil {
if bloberror.HasCode(err, bloberror.BlobNotFound) {
return nil, ErrDEKUnset
}
return nil, fmt.Errorf("downloading DEK from storage: %w", err)
}
defer res.Body.Close()
return io.ReadAll(res.Body)
}
// Put saves a DEK to Azure Blob Storage by key ID.
func (s *AzureStorage) Put(ctx context.Context, keyID string, encDEK []byte) error {
if _, err := s.client.UploadStream(ctx, s.containerName, keyID, bytes.NewReader(encDEK), s.opts.upload); err != nil {
return fmt.Errorf("uploading DEK to storage: %w", err)
}
return nil
}
// createContainerOrContinue creates a new storage container if necessary, or continues if it already exists.
func (s *AzureStorage) createContainerOrContinue(ctx context.Context) error {
_, err := s.client.CreateContainer(ctx, s.containerName, &azblob.CreateContainerOptions{
Metadata: config.StorageTags,
})
if (err == nil) || bloberror.HasCode(err, bloberror.ContainerAlreadyExists) {
return nil
}
return fmt.Errorf("creating storage container: %w", err)
}