Load Balancing: Move temporary files and make them configurable to allow for media upload when load balancing the backoffice

[nikolajlauridsen]

Problem

Previously, temporary files managed through /umbraco/management/api/v1/temporary-file were stored in _hostingEnvironment.LocalTempPath.

In load-balanced setups where Umbraco:CMS:Hosting:LocalTempStorageLocation is configured to "EnvironmentTemp", Umbraco ensures _hostingEnvironment.LocalTempPath is unique per instance. This is critical for Azure deployments where the Umbraco folder is shared between instances.

However, this isolation creates a problem for temporary uploaded files, which need to be accessible across all instances. Consider this scenario:

1. File is uploaded to /umbraco/management/api/v1/temporary-file on server A
2. Request to create media using that file is routed to server B
3. Server B cannot access the file created by server A

Solution

Temporary files now always save to umbraco/Data/TEMP/TemporaryFile/ regardless of the Umbraco:CMS:Hosting:LocalTempStorageLocation setting.

For Azure: This works out of the box since the umbraco folder is shared between instances when scaling out.

For other setups (e.g., Docker): A new configuration option Umbraco:CMS:Hosting:TemporaryFileUploadLocation allows you to specify a custom path (such as a shared drive or volume).

Alternative approach: For advanced scenarios, you can implement a custom ITemporaryFileRepository using external storage like Azure Blob Storage (better suited for a package than core).

Testing

• Configure Umbraco:CMS:Hosting:LocalTempStorageLocation to "EnvironmentTemp" and verify files uploaded via /umbraco/management/api/v1/temporary-file are saved to umbraco/Data/TEMP/TemporaryFile/
• Configure Umbraco:CMS:Hosting:TemporaryFileUploadLocation to a custom location and verify files are uploaded to that folder
• For both configurations, verify media uploads work correctly

[Copilot]

Pull Request Overview

This PR introduces a configurable location for temporary file uploads in Umbraco CMS. Previously, temporary file uploads were hardcoded to LocalTempPath + "/TemporaryFile", and this change allows users to customize this location via configuration settings.

• Adds TemporaryFileUploadLocation configuration property to HostingSettings
• Introduces TemporaryFileUploadPath property to IHostingEnvironment with a default implementation
• Refactors LocalFileSystemTemporaryFileRepository to use the new configurable path

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
src/Umbraco.Core/Configuration/Models/HostingSettings.cs	Adds new TemporaryFileUploadLocation configuration property
src/Umbraco.Core/Hosting/IHostingEnvironment.cs	Adds TemporaryFileUploadPath property with default implementation returning LocalTempPath
src/Umbraco.Web.Common/AspNetCore/AspNetCoreHostingEnvironment.cs	Implements TemporaryFileUploadPath using configuration with fallback to default path
src/Umbraco.Infrastructure/Persistence/Repositories/Implement/LocalFileSystemTemporaryFileRepository.cs	Refactored to use TemporaryFileUploadPath instead of inline path construction

[AndyButland]

Looks good and works as expected. I've tested the outlined scenarios and with a default and custom folder I see the temporary files created in the expected place, and media uploads work with both configurations.