FluxDeployDocs
Topics: WIM Customization

WIM Customization

The WIM Customization engine creates optimized Windows images from source ISOs. It can debloat the image by removing unnecessary AppX packages, apply the latest Windows updates offline, and enable optional features - all without booting the OS.

Prerequisites

  • At least one ISO uploaded to the ISO Library
  • Windows ADK installed on the Core server (required for DISM operations)
  • Sufficient scratch disk space (at least 2x the source WIM size)

Create Windows Image Wizard

Navigate to Windows Images and click Create Windows Image. The 4-step wizard:

Step 1: Source

Select an ISO from the dropdown. The system mounts the ISO and probes it with DISM to detect available Windows editions:

  • Standard images (install.wim) - Direct index selection
  • Compressed images (install.esd) - Also supported with automatic detection

Select the desired edition (e.g., Windows 11 Pro, Windows 11 Enterprise). The image index, version, and a suggested output name are auto-populated.

For a Windows Server ISO, each edition is listed as Server Core (no desktop) and Desktop Experience (full desktop). The wizard pre-selects a Standard Desktop Experience edition; the AppX debloat option is disabled and updates are looked up under the Server product of the Microsoft Update Catalog. See Deploying Windows Server.

Step 2: Options

  • Output Name - Customize the name for the resulting WIM (auto-generated from edition and version)
  • Apply Windows Updates - Downloads and applies the latest cumulative update and .NET Framework update offline via DISM. Updates are sourced from the Microsoft Update Catalog. For a Windows Server image the Server product is searched and the newest security cumulative update is used (see Deploying Windows Server); if the catalog cannot be reached the job continues with any update files you placed in the updates folder.
  • AppX Debloat - Removes non-whitelisted AppX provisioned packages (Store apps like Solitaire, Tips, Weather, etc.) to reduce image size and deployment time

Step 3: Features

Enable Windows optional features to be included in the image. Features are organized into four groups:

Group Features
Frameworks .NET Framework 3.5 (NetFx3)
Virtualization Hyper-V, WSL, Virtual Machine Platform, Containers
Networking Remote Desktop, Telnet Client, TFTP Client, SMB 1.0, SMB Direct
Legacy TIFF IFilter, DirectPlay

Important: Some features (like NetFx3) require the original ISO as a source for SxS payloads. The ISO is automatically re-mounted during feature enablement to provide the /Source: path.

Step 4: Review

A summary card displays all selections. Click Submit to queue the job.

Job Processing

The WimCustomizationJobRunner orchestrates six services in sequence:

  1. IsoSourceService - Mount ISO, copy install.wim to scratch
  2. WimDebloatService - Remove AppX packages (if enabled)
  3. WimUpdateService - Query Microsoft Update Catalog, download and apply updates (if enabled)
  4. WimFeatureService - Enable selected Windows features
  5. WimExportService - Commit changes, export optimized WIM, clean up scratch

Progress is streamed in real time via SignalR to the Image Creation History tab.

After Completion

Completed WIMs are automatically registered in the WIM Library with their SHA-256 hash, ready to be assigned to deployment recipes. Only one WIM customization job runs at a time (configurable via WimCustomization:MaxConcurrentJobs).

Cancellation

Active jobs can be cancelled from the Jobs page or the Image Creation History tab. Cancellation cleans up scratch files and partial outputs.