Multi Install ISO

The engine (or glue) that pollutes vSphere — and now Hyper-V — with brand-new servers, straight from install ISOs. No templates. No golden images. No "who touched the base image" meetings.

Describe the VMs, get a plan with a hash, build the unattended answer media, then apply it with a receipt for every step. When it breaks, and it will, you'll know exactly where.

Status (0.9.1, prerelease): planning, validation, answer-media ISOs, install-ISO checks, and the desktop app are proven offline on Windows. No VM has been built with this release yet. The vSphere and Hyper-V apply paths, and Windows Setup or Anaconda actually eating the generated media, have not been run. Optimism is not evidence. See docs/EVALUATION.md.

What it's for

For the person who gets asked for "a few new servers by this afternoon" and is tired of clicking through Windows Setup, or of keeping golden images alive. You write down the VMs you want (names, sizes, network, OS) in one YAML, JSON or CSV file. Multi Install ISO checks it, turns it into a plan you can review, builds the unattended answer media that installs each server straight from the vendor's ISO (Windows Server, or Rocky/Alma/RHEL), and then creates the VMs on vSphere or local Hyper-V with a receipt for every step. It solves two problems: repeatable builds without templates, and knowing exactly what happened when one of them goes wrong.

How to use

1. Get it. Download MultiInstallIso-<version>-win-x64.zip from Releases and extract it, or build it yourself with build.cmd, which lands in dist\MultiInstallIso-<version>-win-x64\. It needs Windows 10/11, PowerShell 7 and the WebView2 runtime; the .NET runtime is built in.
2. Start the app. Run MultiInstallIso.exe. The Overview page shows what is planned and built, and the Dependencies page shows what is missing (PowerCLI for vSphere, the Hyper-V module for Hyper-V).
3. Describe the VMs. On Definition, open a bundled sample (they are read-only, so save a copy) or your own file, pick vSphere or Hyper-V, and fill in the target. Definitions never hold passwords.
4. Plan. Click Plan. Fix anything it lists as blocking until the plan is clean, then note the plan's SHA-256 on the Plan page; every later step asks for it.
5. Check the install ISOs. On Install ISOs, point at each vendor ISO with the publisher's SHA-256. PASS means the hash matched and the content was recognised.
6. Build the answer media. On Answer media, enter the admin (and domain-join) credentials in the native dialog. You get one small verified ISO per VM. It holds credentials, so delete it once the servers are built.
7. Apply. The Apply page shows a readiness checklist and the exact Build-Cluster.ps1 -Mode Apply command to run in a terminal, with the plan hash and the target you must name. It builds the VMs one at a time and stops at the first failure.
8. Review. Runs lists every plan, media build and apply attempt with its receipts.

Prefer the command line? Everything above is in Command line and step by step in docs/RUNBOOK.md.

The scenario

You need four Windows servers by 5 PM: two IIS, two API. Patched, domain-joined, code pulled. The dev team is waiting to break them with horrible code, and your bonus is on the line.

You could click through Windows Setup four times. Or:

flowchart LR
    A["Definition<br/>YAML / JSON / CSV"] --> B["Plan<br/>validate + SHA-256"]
    B --> C["Answer media<br/>autounattend / ks.cfg ISO<br/>read back + hashed"]
    I["Install ISO<br/>SHA-256 + edition check"] --> D
    C --> D["Apply<br/>hash + target confirmed<br/>one VM at a time"]
    D --> E["Receipts<br/>attempt, per VM, summary"]

Loading

1. Plan. Reads your definition, tells you everything wrong with it (the old samples used a vSphere guest ID that doesn't exist — nobody noticed for years), and writes a read-only plan with a SHA-256.
2. Answer media. One tiny ISO per VM with autounattend.xml (Windows) or ks.cfg (Rocky/Alma/RHEL). Built, read back byte-for-byte, hashed, and locked down because it holds passwords.
3. Apply. Creates the VMs one at a time, but only if you quote the plan hash and name the target out loud. Writes an attempt record before it touches anything and a receipt after every step. Stops at the first failure and doesn't "helpfully" delete anything.

Desktop app

dist\MultiInstallIso-<version>-win-x64\MultiInstallIso.exe (built by build.cmd), or grab the zip from Releases.

• Pages: Overview, Definition (edit and plan), Plan, Answer media, Install ISOs, Apply, Runs, Dependencies, Settings.
• Liquid Glass, because apparently everything is glass now. Settings for on/off, opacity, blur, and Reset. Goes solid on its own when Windows transparency is off, high contrast or forced colours are on, or blur isn't available.
• Native title bar. Tray icon with Show, Hide, Close to tray (on by default), and Exit. Launch it twice and you get the same window back, not two.
• The version button has the Glimmer orb. It thinks when the app is working, flashes when it's done, and turns red when something failed. More honest than most status pages.
• Credentials go into a native dialog and reach the engine on stdin. They never touch the web UI, a command line, or a log.
• Apply isn't run from the window yet. It hands you the exact command to run in a terminal, because the first real run deserves a human watching it.
• MultiInstallIso.exe --smoke runs a self-check, including a real plan and answer-media build. --snapshot <png> [--glass on|off] [--view <page>] renders a page to an image.

Screenshots

The real app, captured on Windows 10. No mockups were harmed.

Definition. Edit YAML, pick vSphere or Hyper-V, plan. Bundled samples are read-only so you can't ruin them.	Plan. Four servers, zero blocking issues, one SHA-256 you'll be quoting for the rest of the day.
Answer media. One ISO per VM, read back and verified. The yellow box is the part where it holds your passwords.	Apply. Readiness checklist, plus the exact command to run. It politely points out you haven't installed PowerCLI.
Runs. Every plan you've ever written, including the one with 12 blocking issues. We don't talk about that one.	Settings. Glass, opacity, blur, close to tray, and where everything lives.

Glass on, glass off. For people who think translucency is a personality:

Glass on	Glass off

Command line

pwsh -File .\Build-Cluster.ps1 -DefinitionPath .\cluster-vms.yaml -PlanOnly
pwsh -File .\Build-Cluster.ps1 -Mode Media -PlanPath <plan> -PlanHash <sha256> -AdminCredential (Get-Credential Administrator)
pwsh -File .\Build-Cluster.ps1 -Mode VerifyMedia -PlanPath <plan>
pwsh -File .\Build-Cluster.ps1 -Mode InspectIso -IsoPath <iso> -ExpectedSha256 <sha256> -ImageName "Windows Server 2022 SERVERSTANDARD"
pwsh -File .\Build-Cluster.ps1 -Mode Apply -PlanPath <plan> -PlanHash <sha256> -ConfirmTarget <vcenter-or-computer>
pwsh -File .\Build-Cluster.ps1 -Mode Dependencies

Add -Json if a machine is reading. Exit codes: 0 fine, 1 your definition or media has a problem, 2 something actually broke. The full walkthrough is in docs/RUNBOOK.md.

What's in here

Path	Purpose
Build-Cluster.ps1	Command-line entry point
powershell\MultiInstallIso\	The engine: YAML reader, validation, plans, answer files, ISO writer/reader, media, apply, providers, dependency map
guest\PostDeploy.ps1	Runs inside new Windows VMs at first logon (Windows PowerShell 5.1, because that's all a fresh server has)
src\MultiInstallIso.App\	.NET 10 WPF + WebView2 desktop app
cluster-vms.yaml, examples\, templates\	Sample definitions
schemas\	JSON schemas
tests\Run-Tests.ps1	Offline tests; no extra modules, no vCenter, no excuses
adapters\	Terraform, Kubernetes, and a plan-only Azure Pipelines file
tools\	Release build and icon generation
legacy\	Retired scripts, kept so nobody asks where they went
docs\	Runbook, prerequisites, definition guide, evaluation, plan

Build

build.cmd

Checks that the version matches everywhere and has a CHANGELOG entry, runs the tests, publishes a self-contained single-file exe, smoke-tests the thing it just published, then zips and hashes it. Tests only: pwsh -File .\tests\Run-Tests.ps1.

Security

• Definitions never hold secrets. Put a password field in one and planning refuses it.
• Answer media does hold credentials. The admin password is encoded, which is not encryption. The domain-join password is plain text, because that's how Windows wants it. The media folder is limited to you, SYSTEM, and Administrators. Delete it after the build.
• Install ISOs are checked against the publisher's SHA-256. Nothing is downloaded or installed behind your back.

Report vulnerabilities privately; see SECURITY.md.

Disclaimer

This tool creates and powers on virtual machines and writes credentials onto installation media. It is provided "as is", without warranty of any kind (see LICENSE). Test every definition against non-production infrastructure first; you are responsible for what it builds. Not affiliated with or endorsed by Broadcom/VMware, Microsoft, Red Hat, or the Rocky and Alma projects; product names describe compatibility only.

Credits and license

MIT. Copyright (c) 2019-2026 mikedopp. See LICENSE.

The release build redistributes the .NET runtime (MIT), the WebView2 SDK loader (BSD-3-Clause), and the Glimmer version orb (MIT, after "orb" by LerSent001, MIT) with its editor's libraries. Every component and its license text is listed in THIRD_PARTY_NOTICES.md and licenses/.