Unable to write to a file in Azure App Service

Question

Situation:

I have been trying to download some files from the Azure Dev Ops repository using GIT API. I then store these files in a new folder with folder name as Office-{MergeCommitID}. Then process these files. And then, delete the temporary folder. In order to download the files I have to get the content of the files and write them to a file in the temporary folder. The code that I use to write to file is:

private void WriteToFile(string fileName, string content, string directoryPath)
        {
            int noOfRetries = 3;
            string filePath = Path.Combine(directoryPath, fileName);
            String processedDirectoryPath = Path.GetDirectoryName(directoryPath);
            for (int i = 1; i <= noOfRetries; i++)
            {
                try
                {
                    if (!Directory.Exists(processedDirectoryPath))
                    {
                        Directory.CreateDirectory(processedDirectoryPath);
                    }

                    if (Directory.Exists(processedDirectoryPath))
                    {

                        ProcessDirectory(processedDirectoryPath);

                        using (FileStream fs = new FileStream(filePath, FileMode.Create, FileAccess.Write))
                        {
                            logger.LogInformation($"WriteToFile trying to write the {content} to file: {filePath}");
                            var bytes = Encoding.UTF8.GetBytes(content);
                            fs.Write(bytes);
                        }
                        logger.LogInformation($"WriteToFile: was successful in writing to the file: {filePath}");
                        break;
                    }
                    else
                    {

                        logger.LogError($"WriteToFile: Directory ({directoryPath})does not exist!");
                        throw new DirectoryNotFoundException();
                    }
                }
                catch(Exception ex)
                {
                    if(i == 1)
                    {
                        logger.LogWarning($"An exception: {ex} occured while writing to the file: {filePath}");
                    }
                    else if(i == noOfRetries)
                    {
                        string errorMessage = $"WriteToFile method failed due to the following exception: {ex} while writing on the file: {filePath}";
                        logger.LogError(errorMessage);
                        throw ex;
                    }
                }
            }

I have added the ProcessDirectory method to check if it was possible or not to access the directory as it the application was earlier failing on the line where I create the FileStream object. The ProcessDirectory function looks like this:

 public void ProcessDirectory(string targetDirectory)
        {
            // Process the list of files found in the directory.
            string[] fileEntries = Directory.GetFiles(targetDirectory);
            foreach (string fileName in fileEntries)
                ProcessFile(fileName);

            // Recurse into subdirectories of this directory.
            string[] subdirectoryEntries = Directory.GetDirectories(targetDirectory);
            foreach (string subdirectory in subdirectoryEntries)
                ProcessDirectory(subdirectory);
        }

        // Insert logic for processing found files here.
        public void ProcessFile(string path)
        {
            logger.LogInformation("Processed file '{0}'.", path);
        }

I am getting the following exception when I try the above process:

System.IO.DirectoryNotFoundException: Could not find a part of the path 'D:\home\site\wwwroot\Office-12aae1d40b045f5612b175742a7c720452143ca2'.
   at SecurityCodeScannerTask.DataProcessor.GitDataProcessor.WriteToFile(String fileName, String content, String directoryPath) in C:\Users\sakathuria\source\repos\OESecTools\SecurityCodeScanner\SecurityCodeScannerTask\DataProcessor\GitDataProcessor.cs:line 655
   at SecurityCodeScannerTask.DataProcessor.GitDataProcessor.DownloadFilesPerCommit(List`1 changedFiles, GitData gitData) in C:\Users\sakathuria\source\repos\OESecTools\SecurityCodeScanner\SecurityCodeScannerTask\DataProcessor\GitDataProcessor.cs:line 461

I got the following error in the logs that I have added:

WriteToFile method failed due to the following exception: System.IO.DirectoryNotFoundException: Could not find a part of the path 'D:\home\site\wwwroot\Office-12aae1d40b045f5612b175742a7c720452143ca2'.
   at System.IO.Enumeration.FileSystemEnumerator`1.CreateDirectoryHandle(String path, Boolean ignoreNotFound)
   at System.IO.Enumeration.FileSystemEnumerator`1.Init()
   at System.IO.Enumeration.FileSystemEnumerator`1..ctor(String directory, Boolean isNormalized, EnumerationOptions options)
   at System.IO.Enumeration.FileSystemEnumerable`1..ctor(String directory, FindTransform transform, EnumerationOptions options, Boolean isNormalized)
   at System.IO.Enumeration.FileSystemEnumerableFactory.UserFiles(String directory, String expression, EnumerationOptions options)
   at System.IO.Directory.InternalEnumeratePaths(String path, String searchPattern, SearchTarget searchTarget, EnumerationOptions options)
   at System.IO.Directory.GetFiles(String path)
   at SecurityCodeScannerTask.DataProcessor.GitDataProcessor.ProcessDirectory(String targetDirectory) in C:\Users\sakathuria\source\repos\OESecTools\SecurityCodeScanner\SecurityCodeScannerTask\DataProcessor\GitDataProcessor.cs:line 584
   at SecurityCodeScannerTask.DataProcessor.GitDataProcessor.WriteToFile(String fileName, String content, String directoryPath) in C:\Users\sakathuria\source\repos\OESecTools\SecurityCodeScanner\SecurityCodeScannerTask\DataProcessor\GitDataProcessor.cs:line 626 while writing on the file: D:\home\site\wwwroot\Office-12aae1d40b045f5612b175742a7c720452143ca2\-cloudbuildtools-tools-NuTest.UnitTests-packages.lock.json

One reason that can be possible is that I am using Azure Dev Ops pipeline for deploying the code on AppService and it uses ZipDeploy.

Unable to Create Directories due to ZipDeploy

I tried to publish the code using Visual Studio on AppService but it gave me the same error again. Any help in resolving this issue is much appreciated.

Answer 1

Hello @Sarthak Kathuria - Thanks for reaching out.

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