Effectively Communicating ArcGIS Enterprise Downtime

April 19, 2024

Amanda De Medeiros

In the intricate web of ArcGIS Enterprise operations, downtime is the enemy of productivity. Imagine this scenario: your web adaptor mistakenly transmitting requests to the ArcGIS Enterprise portal during system maintenance, triggering a cascade of service disruptions and user frustrations. How do we circumvent such scenarios? While downtime might be necessary in certain maintenance scenarios, we can set up a maintenance page for our users.

When Downtime is Unavoidable

In a non-highly available setup of ArcGIS Enterprise, downtime is sometimes necessary during prolonged periods of patching, such as when running the Portal Validation and Repair tool. In such instances, it's beneficial to prevent traffic from entering the environment and instead present users with a notice indicating that maintenance is underway.

Adding an Offline .htm File

For clients with architectures involving custom load balancers and/or reverse proxies, traffic interception at the ingress point and the implementation of URL rewrite rules can direct users to a maintenance page until the environment is available again.

For clients solely relying on the ArcGIS Web Adaptors in Microsoft’s IIS without additional architectural components for web traffic control, adding a custom .htm file into the ArcGIS Enterprise portal's web adaptor folder can achieve a similar effect.

Microsoft documents that by adding a file called app_offline.htm into an IIS web app's root directory, the ASP.NET Core Module will effectively shut down that app, displaying the app_offline.htm page instead of allowing access to the web application. This approach can restrict the web adaptor from sending traffic to the ArcGIS Enterprise portal during downtime.

In the example below, a file named app_offline.htm has been added to the root location of a web adaptor named "portal" (e.g., C:\inetpub\wwwroot\portal). While the file is present in the directory, attempting to access the environment via the web adaptor URL will return a notice indicating that the environment is offline.

$The File Explorer directory C:\inetpub\wwwroot\portal), with a red box around the newly inputted app_offline.htm file. On the left is the offline message stating “Offline. This site is offline for maintenance.”$

Then, once the downtime is complete and the ArcGIS Enterprise portal is ready to receive traffic from the web adaptor again, you can either rename or delete the file from the directory and the web adaptor URL will start to resolve properly.

$The File Explorer directory C:\inetpub\wwwroot\portal), the app_offline.htm file has been removed and the Portal homepage is displayed on the left.$

Additional Notes:

Make sure you don't alter, delete or otherwise compromise the existing files in the folder, as they are critical components of the web adaptor's functionality. The only change that should be made to the folder is adding the file in when downtime is needed and renaming/removing it once downtime is complete.

This approach can also be applied to the GIS Server's web adaptor in non-federated environments. However, it's worth noting that at version 10.7.1 and later, the web adaptor will not send requests to a GIS Server machine that has had its underMaintenance flag set to true. Therefore, the core functionality is available to achieve the same effect in that scenario.

The screenshot above showcases a simple app_offline.htm, which is linked here. However, clients can customize the file as needed. For instance, they may want to incorporate their own corporate branding and style.

This blog was co-written with Rahul Chandra.