duplicati/Duplicati/Library/Backend/AzureBlob/AzureBlobBackend.cs

// Copyright (C) 2025, The Duplicati Team
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using Azure;
using Azure.Storage.Blobs.Models;
using Duplicati.Library.Interface;
using Duplicati.Library.Utility.Options;

namespace Duplicati.Library.Backend.AzureBlob
{
    // ReSharper disable once UnusedMember.Global
    // This class is instantiated dynamically in the BackendLoader.
    public class AzureBlobBackend : IStreamingBackend
    {
        private readonly AzureBlobWrapper _azureBlob;

        // ReSharper disable once UnusedMember.Global
        // This constructor is needed by the BackendLoader.
        public AzureBlobBackend()
        {
            _azureBlob = null!;
        }

        // ReSharper disable once UnusedMember.Global
        // This constructor is needed by the BackendLoader.
        public AzureBlobBackend(string url, Dictionary<string, string?> options)
        {
            var uri = new Utility.Uri(url);
            uri.RequireHost();

            var containerName = uri.Host.ToLowerInvariant();

            var auth = AuthOptionsHelper.ParseWithAlias(options, uri, "azure-account-name", "azure-access-key");
            var timeouts = TimeoutOptionsHelper.Parse(options);

            var sasToken = options.GetValueOrDefault("azure-access-sas-token");
            if (!auth.HasUsername)
                throw new UserInformationException(Strings.AzureBlobBackend.NoStorageAccountName, "AzureNoAccountName");

            if (!auth.HasPassword && string.IsNullOrWhiteSpace(sasToken))
                throw new UserInformationException(Strings.AzureBlobBackend.NoAccessKeyOrSasToken, "AzureNoAccessKeyOrSasToken");

            _azureBlob = new AzureBlobWrapper(auth.Username!, auth.Password, sasToken, containerName, timeouts);
        }

        public string DisplayName => Strings.AzureBlobBackend.DisplayName;

        public string ProtocolKey => "azure";

        public IAsyncEnumerable<IFileEntry> ListAsync(CancellationToken cancelToken)
            => _azureBlob.ListContainerEntriesAsync(cancelToken);

        public async Task PutAsync(string remotename, string localname, CancellationToken cancelToken)
        {
            await using var fs = File.Open(localname,
                FileMode.Open, FileAccess.Read, FileShare.Read);
            await PutAsync(remotename, fs, cancelToken).ConfigureAwait(false);
        }

        public Task PutAsync(string remotename, Stream input, CancellationToken cancelToken)
        {
            return WrapWithExceptionHandler(_azureBlob.AddFileStream(remotename, input, cancelToken));
        }

        public async Task GetAsync(string remotename, string localname, CancellationToken cancellationToken)
        {
            await using var fs = File.Open(localname,
                FileMode.Create, FileAccess.Write,
                FileShare.None);
            await GetAsync(remotename, fs, cancellationToken).ConfigureAwait(false);
        }

        public Task GetAsync(string remotename, Stream output, CancellationToken cancellationToken)
        {
            return WrapWithExceptionHandler(_azureBlob.GetFileStreamAsync(remotename, output, cancellationToken));
        }

        public Task DeleteAsync(string remotename, CancellationToken cancellationToken)
        {
            return WrapWithExceptionHandler(_azureBlob.DeleteObjectAsync(remotename, cancellationToken));
        }

        public IList<ICommandLineArgument> SupportedCommands
        {
            get
            {
                return [
                    new CommandLineArgument("azure-account-name",
                        CommandLineArgument.ArgumentType.String,
                        Strings.AzureBlobBackend.StorageAccountNameDescriptionShort,
                        Strings.AzureBlobBackend.StorageAccountNameDescriptionLong,
                        null,
                        [AuthOptionsHelper.AuthUsernameOption]),
                    new CommandLineArgument("azure-access-key",
                        CommandLineArgument.ArgumentType.Password,
                        Strings.AzureBlobBackend.AccessKeyDescriptionShort,
                        Strings.AzureBlobBackend.AccessKeyDescriptionLong,
                        null,
                        [AuthOptionsHelper.AuthPasswordOption]),
                    new CommandLineArgument("azure-access-sas-token",
                        CommandLineArgument.ArgumentType.Password,
                        Strings.AzureBlobBackend.SasTokenDescriptionShort,
                        Strings.AzureBlobBackend.SasTokenDescriptionLong),
                    .. TimeoutOptionsHelper.GetOptions()
                ];
            }
        }

        public string Description => Strings.AzureBlobBackend.DescriptionV2;

        public Task<string[]> GetDNSNamesAsync(CancellationToken cancelToken) => Task.FromResult(_azureBlob.DnsNames);

        public Task TestAsync(CancellationToken cancellationToken)
            => this.TestListAsync(cancellationToken);

        public Task CreateFolderAsync(CancellationToken cancellationToken)
        {
            return WrapWithExceptionHandler(_azureBlob.AddContainerAsync(cancellationToken));
        }

        /// <summary>
        /// Wraps the task with exception handling
        /// </summary>
        private async Task WrapWithExceptionHandler(Task task)
        {
            try
            {
                await task.ConfigureAwait(false);
            }
            catch (RequestFailedException e)
                when (e.Status == 404
                      || e.ErrorCode == BlobErrorCode.BlobNotFound
                      || e.ErrorCode == BlobErrorCode.ResourceNotFound)
            {
                throw new FileMissingException(e.Message, e);
            }
            catch (RequestFailedException e)
                when (e.ErrorCode == BlobErrorCode.ContainerNotFound
                      || e.ErrorCode == BlobErrorCode.ContainerBeingDeleted
                      || e.ErrorCode == BlobErrorCode.ContainerDisabled)
            {
                throw new FolderMissingException(e.Message, e);
            }
        }

        public void Dispose()
        {

        }
    }
}