What options are there to deploy .NET applications to a server farm? Unless you're at a small web shop, you've likely never had to encounter this question. But this last month, it was this very question that I began to ponder as I began a rotation to a different group whose responsibilities include managing builds for the weekly release and the deployment to a web farm.
So what options are there? At my previous job, the code deployments were a manual process where the IT group would run an MSI file we generated during the build and use this to deploy to the .NET code to the web and application servers. As the code was being deployed, SQL scripts would be executed via a custom tool designed to execute the scripts on multiple databases at once to ease in this step of the deployment and to better record the errors.
But is a manual process the only way to go? Certainly not. One option is to utilize Windows Group Policy to remotely install an MSI containing the updated code. While developers may not be familiar with this functionality, IT staff members will likely have used this before to manage the software on desktops or servers remotely.
Another option is to utilize Microsoft's Web Deploy Tool to create deployment packages to push out to code to other servers. This tool can take a snapshot of a website on one server and replicate it to another, or identify changes to a server and replicate them to another server. Deploying these changes is still a manual process, but the Web Deploy tool is a powerful tool that can make the deployment process easier.
Perhaps the most intriguing option out there is Microsoft's Web Farm Framework. This tool can work with the Web Deploy tool or an MSI to automatically handle the deployment to a farm of servers. According to Scott Gu's article on the tool, the Web Farm Framework is an IIS extension that is installed on each server in the farm. One server is identified as the 'Primary' server. Any changes made to this server will be replicated to the other servers in the farm, one at a time in order to keep the entire farm operational.
The Web Farm Framework makes deployments easy, but as with many tools, there are tradeoffs. Deployments will take longer as only one server is pulled from the farm at a time. Because of this strategy, all but one server can respond to requests during the deployment, yet the servers will be on different versions of the code. And what if there is a central database that the web farm utilizes that must be updated? When should the database be updated?
What's the best option for deploying .NET code to a Server Farm? It depends on your situation.
If you have a strong IT staff, perhaps they can administer the Web Farm using Windows Group Policy and MSI's that are created during the build process.
If the IT staff is not familiar with Windows Group Policy, perhaps Web Farm Framework is worthwhile option, especially if the system cannot be taken down during an upgrade.
If you have the spare development staff, your best option might be to build your own tools. This requires a group of developers with an understanding of how the system works as a whole, but with the effort, you can build yourself a tool-set geared directly towards your server farm.
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