尝试在 Web API 请求上检索 Azure Blob 时出现 403 错误

Question

我正在尝试让经过身份验证的（通过 JWT）GET 请求返回存储在 Azure blob 中的图像。当我在本地机器上运行项目并使用邮递员请求图像并且请求通过时，我确实得到了我请求的图像。但是，一旦我将代码部署到 Azure 并点击相同的端点，我就会得到 403。代码在我尝试调用 DownloadToStreamAsync 的那一行失败。这是我正在使用的代码：

public async Task<BlobDownloadModel> DownloadBlob(Guid blobId)
    {
        try
        {
            //get picture record
            Picture file = await _media.GetPictureAsync(blobId);

            await _log.CreateLogEntryAsync("got picture record");

            // get string format blob name
            var blobName = file.PictureId.ToString() + file.Extension;

            await _log.CreateLogEntryAsync("got name of blob " + blobName);

            if (!String.IsNullOrEmpty(blobName))
            {
                await _log.CreateLogEntryAsync("blob not empty");

                var blob = _container.GetBlockBlobReference(blobName);

                await _log.CreateLogEntryAsync("got blob: " + blob.ToString());

                var ms = new MemoryStream();

                await blob.DownloadToStreamAsync(ms);

                await _log.CreateLogEntryAsync("blob downloaded to memory stream");

                var lastPos = blob.Name.LastIndexOf('/');
                var fileName = blob.Name.Substring(lastPos + 1, blob.Name.Length - lastPos - 1);

                var download = new BlobDownloadModel
                {
                    BlobStream = ms,
                    BlobFileName = fileName,
                    BlobLength = blob.Properties.Length,
                    BlobContentType = blob.Properties.ContentType
                };

                return download;
            }
        }
        catch(Exception ex)
        {
            await _log.CreateLogEntryAsync("exception thrown: " + ex.ToString());
        }

如果能得到任何帮助，我将不胜感激。

更新：

我把我的代码改成这个并再次尝试：

public async Task<AzureBlobModel> DownloadBlob(Guid blobId)
    {
        try
        {
            //get picture record
            Picture file = await _media.GetPictureAsync(blobId);

            await _log.CreateLogEntryAsync("got picture record");

            // get string format blob name
            var blobName = file.PictureId.ToString() + file.Extension;

            await _log.CreateLogEntryAsync("got name of blob " + blobName);

            if (!String.IsNullOrEmpty(blobName))
            {
                await _log.CreateLogEntryAsync("blob not empty");

                var blob = _container.GetBlockBlobReference(blobName);

                await _log.CreateLogEntryAsync("got blob: " + blob.ToString());

                // Strip off any folder structure so the file name is just the file name
                var lastPos = blob.Name.LastIndexOf('/');
                var fileName = blob.Name.Substring(lastPos + 1, blob.Name.Length - lastPos - 1);

                await _log.CreateLogEntryAsync("got fileName: " + fileName);

                //await blob.DownloadToStreamAsync(ms);

                await _log.CreateLogEntryAsync("about to open read stream");

                var stream = await blob.OpenReadAsync();

                await _log.CreateLogEntryAsync("opened read stream");

                var result = new AzureBlobModel()
                {
                    FileName = fileName,
                    FileSize = blob.Properties.Length,
                    Stream = stream,
                    ContentType = blob.Properties.ContentType
                };

                await _log.CreateLogEntryAsync("blob downloaded to memory stream");

                return result;

                // Build and return the download model with the blob stream and its relevant info
                //var download = new BlobDownloadModel
                //{
                //    BlobStream = ms,
                //    BlobFileName = fileName,
                //    BlobLength = blob.Properties.Length,
                //    BlobContentType = blob.Properties.ContentType
                //};

                //return download;
            }
        }
        catch(Exception ex)
        {
            await _log.CreateLogEntryAsync("exception thrown: " + ex.ToString());
        }

        await _log.CreateLogEntryAsync("returning null");

        // Otherwise
        return null;
    }

最后一次尝试的日志结果是这样的：

请求已收到并通过身份验证，UTC 时间戳：2017 年 3 月 10 日上午 5:28:26 - 上午 5:28:26
收到的 ID：b3bc7faf-0c86-4ce2-af84-30636825a485 - 5:28:27 AM
得到图片记录-5:28:27 AM
得到 blob b3bc7faf-0c86-4ce2-af84-30636825a485.JPG - 5:28:27 AM
的名称 blob 不为空 - 上午 5:28:27
得到 blob：Microsoft.WindowsAzure.Storage.Blob.CloudBlockBlob - 5:28:27 AM
得到文件名：b3bc7faf-0c86-4ce2-af84-30636825a485.JPG - 5:28:27 AM
即将打开读取流 - 上午 5:28:27

我能够检索文件/blob 的名称，从而消除了错误的帐户密钥作为问题的罪魁祸首。

解决方案

我能够让我的代码使用以下代码：

public async Task<AzureBlobModel> DownloadBlob(Guid blobId)
    {
        try
        {
            //get picture record
            Picture file = await _media.GetPictureAsync(blobId);

            // get string format blob name
            var blobName = file.PictureId.ToString() + file.Extension;

            if (!String.IsNullOrEmpty(blobName))
            {
                var blob = _container.GetBlockBlobReference(blobName);

                // Strip off any folder structure so the file name is just the file name
                var lastPos = blob.Name.LastIndexOf('/');
                var fileName = blob.Name.Substring(lastPos + 1, blob.Name.Length - lastPos - 1);

                var fileLength = blob.Properties.Length;
                var stream = await blob.OpenReadAsync();

                var result = new AzureBlobModel()
                {
                    FileName = fileName,
                    FileSize = blob.Properties.Length,
                    Stream = stream,
                    ContentType = blob.Properties.ContentType
                };

                return result;
            }
        }
        catch(Exception ex)
        {
            await _log.CreateLogEntryAsync("exception thrown: " + ex.ToString());
        }

        await _log.CreateLogEntryAsync("returning null");

        // Otherwise
        return null;
    }

Answer 1

但是，一旦我将代码部署到 Azure 并点击相同的端点，我就会得到 403。

首先，请检查您的 Azure 帐户和密钥以确保它们正确无误。其次，请检查服务器上的时钟。存储服务确保请求到达服务的时间不超过 15 分钟。如果您的服务器上的时间与存储服务器上的时间不同步，则会出现 403 错误。

Answer 2

我能够使用以下代码解决问题：

public async Task<AzureBlobModel> DownloadBlob(Guid blobId)
    {
        try
        {
            //get picture record
            Picture file = await _media.GetPictureAsync(blobId);

            // get string format blob name
            var blobName = file.PictureId.ToString() + file.Extension;

            if (!String.IsNullOrEmpty(blobName))
            {
                var blob = _container.GetBlockBlobReference(blobName);

                // Strip off any folder structure so the file name is just the file name
                var lastPos = blob.Name.LastIndexOf('/');
                var fileName = blob.Name.Substring(lastPos + 1, blob.Name.Length - lastPos - 1);

                var fileLength = blob.Properties.Length;
                var stream = await blob.OpenReadAsync();

                var result = new AzureBlobModel()
                {
                    FileName = fileName,
                    FileSize = blob.Properties.Length,
                    Stream = stream,
                    ContentType = blob.Properties.ContentType
                };

                return result;
            }
        }
        catch(Exception ex)
        {
            await _log.CreateLogEntryAsync("exception thrown: " + ex.ToString());
        }

        await _log.CreateLogEntryAsync("returning null");

        // Otherwise
        return null;
    }