Custom Applications (Existing Applications)

A custom application is an application that does not integrate with Service Fabric, meaning it does not reference any Service Fabric binaries. Examples of custom applications are Node.js applications, Java applications, MongoDB, and so on. Benefits of running custom applications in Service Fabric are high availability of the application, health reporting, rolling upgrade support, and higher density.

• High availability: Applications that run in Service Fabric are highly available out of the box. Service Fabric makes sure that one instance of an application is always up and running.

• Health monitoring: Out-of-the-box Service Fabric health monitoring detects if the application is up and running and provides diagnostics information in the case of a failure.

• Application lifecycle management: Besides no downtime upgrades, Service Fabric also enables rolling back to the previous version if there is an issue during upgrade.

• Density: You can run multiple applications in a cluster, which eliminates the need for each application to run on its own hardware.

Custom applications are packaged and deployed in the same way as Service Fabric applications. The service manifest contains additional metadata that tells Service Fabric where it can find the binaries of the application and how to execute it. Once the package is copied into the image store, Service Fabric pulls down the application package to the nodes and executes the custom applications. This article provides more information for deploying custom applications: https://azure.microsoft.com/en-us/documentation/articles/service-fabric-deploy-existing-app/. One can easily see that instead of starting custom applications, Service Fabric could spin up Docker or Windows containers, rather than just inside processes and Windows Job Objects as they do currently.