Export and back up your SQL Azure databases nightly into blob storage

With Azure I have always believed, if you can do it with the Azure Management Portal then you can do it with a REST API. So I thought it would be a breeze to make an automated job to run every night to export and back up my SQL Azure database into a BACPAC file in blob storage. I was suprised to find scheduling bacpac exports of your SQL Azure databases is not documented in the Azure Service Management API. Maybe it is because the bacpac exporting and importing is in beta? Nevermind. I successfully have a worker role backing up my databases and here's how:

It is a REST API so you can't use nice WCF to handle all your POST data for you but there is a trick still to avoid writing out all your XML parameters by hand and instead strong typing a few classes.

Go to your worker role or console application and add a service reference to your particular DACWebService (it varies by region):

• North Central US: https://ch1prod-dacsvc.azure.com/DACWebService.svc
• South Central US: https://sn1prod-dacsvc.azure.com/DACWebService.svc
• North Europe: https://db3prod-dacsvc.azure.com/DACWebService.svc
• West Europe: https://am1prod-dacsvc.azure.com/DACWebService.svc
• East Asia: https://hkgprod-dacsvc.azure.com/DACWebService.svc
• Southeast Asia: https://sg1prod-dacsvc.azure.com/DACWebService.svc

Once you import this Service Reference you will have some new classes that will come in handy in the following code:

//these details are passed into my method but here is an example of what is needed
var dbServerName = "qwerty123.database.windows.net";
var dbName = "mydb";
var dbUserName = "myuser";
var dbPassword = "Password!";

//storage connection is in my ServiceConfig
//I know these the CloudStorageConnection can be obtained in one line of code
//but this way is necessary to be able to get the StorageAccessKey later
var storageConn = RoleEnvironment.GetConfigurationSettingValue("Storage.ConnectionString");
var storageAccount = CloudStorageAccount.Parse(storageConn);

//1. Get your blob storage credentials
var credentials= new BlobStorageAccessKeyCredentials();
//e.g. https://myStore.blob.core.windows.net/backups/mydb/2012-05-22.bacpac
credentials.Uri = string.Format("{0}backups/{1}/{2}.bacpac",
    storageAccount.BlobEndpoint,
    dbName,
    DateTime.UtcNow.ToString("yyyy-MM-dd"));
credentials.StorageAccessKey = ((StorageCredentialsAccountAndKey)storageAccount.Credentials)
                                   .Credentials.ExportBase64EncodedKey();

//2. Get the DB you want to back up
var connectionInfo = new ConnectionInfo();
connectionInfo.ServerName = dbServerName;
connectionInfo.DatabaseName = dbName;
connectionInfo.UserName = dbUserName;
connectionInfo.Password = dbPassword;

//3. Fill the object required for a successful POST
var export = new ExportInput();
export.BlobCredentials = credentials;
export.ConnectionInfo = connectionInfo;

//4. Create your request
var request = WebRequest.Create("https://am1prod-dacsvc.azure.com/DACWebService.svc/Export");
request.Method = "POST";
request.ContentType = "application/xml";
using (var stream = request.GetRequestStream())
{
    var dcs = new DataContractSerializer(typeof(ExportInput));
    dcs.WriteObject(stream, export);
}

//5. make the POST!
using (var response = (HttpWebResponse)request.GetResponse())
{
    if (response.StatusCode != HttpStatusCode.OK)
    {
        throw new HttpException((int)response.StatusCode, response.StatusDescription);
    }
}

This code would run in a scheduled task or worker role to be set for 2am each night for example. It is important you have appropriate logging and notifications in the event of failure.

Conclusion

This sends off the request to start the back up / export of database into a bacpac file. The success of this is no indication that the back up was successful, only the request submition. If your credentials are wrong you will get a 200 OK response but it the back up will fail silently later.

To see if it has been successful you can check on the status of your exports via the Azure Management Portal, or by waiting a short while and having a look in your blob storage.

I have not covered Importing because, really, exporting is the boring yet important activity that must happen regularly (such as nightly). Importing is the one you do on the odd occassion when there has been a disaster and the Azure Management Portal is well suited to such an occassion.