Windows Azure Web Sites: Sample C# Web Job code to perform a simple retention policy over website backup files

BackupRetentionPolicyWebJob

// ---------------------------------------------------------------------------------- 
// Windows Azure Web Sites
//  
// Copyright (c) Microsoft Corporation. All rights reserved. 
//  
// THIS CODE AND INFORMATION ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,  
// EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES  
// OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE. 
// ---------------------------------------------------------------------------------- 

using System;
using System.Configuration;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Auth;
using Microsoft.WindowsAzure.Storage.Blob;

namespace SimpleBackupWebJob
{
    class RetentionPolicy
    {

        // Name of the container in the blob storage used to place the backup files
        // The name of this container is always the same in any storage account that has website backup set up
        const string BACKUP_FILES_CONTAINER_NAME = "websitebackups"; 

        static void Main(string[] args)
        {

            CloudStorageAccount account = null;
            CloudBlobContainer blobContainer = null;
            int maxDaysToKeep = int.MaxValue;
            string websiteName = "";

            // Uses the Application settings to connect the storage account
            try 
            { 
                account = new CloudStorageAccount(new StorageCredentials(ConfigurationManager.AppSettings["BACKUP_STORAGE_ACCOUNT"], ConfigurationManager.AppSettings["BACKUP_STORAGE_ACCOUNT_KEY"]), false);
            }
            catch (Exception e) 
            {
                throw new Exception("Couldn't connect to the specified storage account. Make sure your application settings has BACKUP_STORAGE_ACCOUNT and BACKUP_STORAGE_ACCOUNT_KEY properly set up.", e); 
            }

            // Connects to the blob container that has the backup files
            try 
            {
                blobContainer = account.CreateCloudBlobClient().GetContainerReference(BACKUP_FILES_CONTAINER_NAME);
            }
            catch (Exception e) 
            {
                throw new Exception("Couldn't find " + BACKUP_FILES_CONTAINER_NAME + " blob. Retention process will not continue.", e); 
            }
            

            maxDaysToKeep = int.Parse(ConfigurationManager.AppSettings["BACKUP_RETENTION_MAX_DAYS_TO_KEEP"]);
            Console.WriteLine("Config Reading: BACKUP_RETENTION_MAX_DAYS_TO_KEEP=" + maxDaysToKeep);
            websiteName = ConfigurationManager.AppSettings["WEBSITE_SITE_NAME"]; 
            Console.WriteLine("Config Reading: WEBSITE_SITE_NAME=" + websiteName);

            int numBackupFiles = 0;
            int numBackupFilesDeleted = 0;
            DateTimeOffset expirationTimestamp = new DateTimeOffset(DateTime.Today.AddDays(-maxDaysToKeep)); 
            
            // iterate over all blob items in the backup container
            foreach (CloudBlockBlob blobItem in blobContainer.ListBlobs())
            {
                string fileName = blobItem.Name.ToLower();
                
                // Select only blob items that start with the website name and end with .zip or .xml
                if (fileName.StartsWith(websiteName,StringComparison.OrdinalIgnoreCase)
                    && (fileName.EndsWith(".zip") || fileName.EndsWith(".xml")))
                {
                    numBackupFiles++;

                    // Check if blobItem last modified date is older than the number of informed in the retention policy parameter
                    if (DateTimeOffset.Compare(blobItem.Properties.LastModified.Value, expirationTimestamp) < 0)
                    {
                        Console.WriteLine("Deleting " + blobItem.Name + " Last Modified=" + blobItem.Properties.LastModified.Value.LocalDateTime.ToShortDateString());
                        // actually delete the blob item
                        blobItem.Delete(DeleteSnapshotsOption.None, null, null, null);
                        numBackupFilesDeleted++;
                    }
                }
            }

            //Summarize results of the job execution
            Console.WriteLine("Total backup files found = " + numBackupFiles);
            Console.WriteLine("Total backup files deleted = " + numBackupFilesDeleted);
        }

    }
}