Azure Tip of the Day: Determine if running in Dev Fabric or Azure Fabric

One potential goal, when writing a new Azure application, is to support running in both Azure-hosted and non-Azure environments. The SDK gives us an easy way to check this:

            if (RoleEnvironment.IsAvailable)
            {
                // Azure-specific actions
            }

With this check, you could, say, build a class library that has specific behaviors depending on the environment in which it’s running.

Now, let’s assume the Azure environment is available, and you need to take a specific action depending on whether you’re running in the Dev Fabric vs. the Azure Fabric. Unfortunately, there’s no specific method or property in RoleEnvironment that helps us out.

This brings me to today’s tip: Determining whether an app is running in Dev Fabric or Azure Fabric.


The Deployment ID

While there’s no direct call such as RoleEnvironment.InDevFabric, there’s a neat trick I use, making it trivial to figure out. A disclaimer first: This trick is dependent on the specific way the Dev Fabric and Azure Fabric generate their Deployment IDs. This could possibly change with a future SDK update.


Whenever you deploy an Azure application, the deployment gets a unique Deployment ID. This value is available in:
RoleEnvironment.DeploymentId.

As it turns out, the deployment ID has two different formats, depending on runtime environment:

• Dev Fabric: The deployment ID takes the form of  deployment(n), where n is sequentially incremented with each Dev Fabric deployment.
• Azure Fabric: The deployment ID is a Guid.

With this little detail, you can now write a very simple method to determine whether you’re in Dev Fabric or Azure Fabric:
        private bool IsRunningInDevFabric()

        {
            // easiest check: try translate deployment ID into guid
            Guid guidId;
            if (Guid.TryParse(RoleEnvironment.DeploymentId, out guidId))
                return false;   // valid guid? We're in Azure Fabric
            return true;        // can't parse into guid? We're in Dev Fabric
        }

 Taking this one step further, I wrote a small asp.net demo app that prints out the deployment ID, along with the current instance ID. For example, here’s the output when running locally in my Dev Fabric:

 Here’s the same app, published to, and running in, the Azure Fabric:




Try it yourself

I uploaded my demo code so you can try it out yourself. You’ll need to change the diagnostic storage account information in the asp.net role configuration, prior to deploying it to Azure.