feat: Add disk image format selection with ASIF support #1094

fkorotkov · 2025-06-14T17:21:16Z

Used http://augmentcode.com/ to generate the following in 3 prompts. See each commit.

This adds support ASIF (Apple Sparse Image Format) provides better performance on macOS 26 Tahoe and later systems while maintaining compatibility with existing RAW disk workflows.

In addition each VM config now has a metadata about the format and tart set --disk-size N will use diskutils to resize which is reflected in the VM (no need to SSH and run the extra step inside of the guest).

CLAassistant · 2025-06-14T17:21:21Z

All committers have signed the CLA.

- Use .uncached caching mode for ASIF disks to avoid Virtualization framework compatibility issues - Improve caching mode selection logic for better maintainability - Fix compiler warning by changing var to let for attachment variable This resolves VM startup failures when using ASIF disk format by ensuring proper disk attachment configuration.

Sources/tart/VM.swift

Change from 'brew install --cask goreleaser-pro' to 'brew install --cask goreleaser/tap/goreleaser-pro' for proper installation from the official goreleaser tap.

- Remove .vscode/launch.json from repository - Add .vscode/ to .gitignore to prevent VS Code settings from being tracked

- Add support for resizing ASIF disk images using diskutil image resize - Detect disk format from VM config and route to appropriate resize method - Use diskutil image info to get current ASIF disk size and validate resize - Remove restriction that prevented ASIF disk resizing in Set command - Add FailedToResizeDisk error case for proper error handling - Maintain backward compatibility with raw disk resizing - Add comprehensive size validation to prevent data loss

Add support for --disk-format argument to specify disk image format when creating VMs with from_ipsw or from_iso. Changes: - Add DiskFormat field to Config struct with validation - Support 'raw' (default) and 'asif' disk formats - Pass --disk-format argument to tart create command - Update HCL2 specification for new field - Add comprehensive documentation - Include example configuration demonstrating usage ASIF (Apple Sparse Image Format) provides better performance but requires macOS 15+ for usage and macOS 26+ for creation. Implements support for cirruslabs/tart#1094

Tests/TartTests/DiskImageFormatTests.swift

Sources/tart/Commands/Create.swift

Sources/tart/DiskImageFormat.swift

Sources/tart/VM.swift

edigaryev · 2025-06-17T12:27:41Z

Sources/tart/VMDirectory.swift

    try diskFileHandle.close()
  }

+  private func resizeASIFDisk(_ sizeGB: UInt16) throws {


It would be logical to move this function and functions below to DiskImageFormat instead now that we have it.

Sources/tart/VMDirectory.swift

Sources/tart/VMDirectory+OCI.swift

Co-authored-by: Nikolay Edigaryev <edigaryev@gmail.com>

- Rename testFormatArgument to testCaseInsensitivity for clarity - Remove redundant 'raw' and 'invalid' test cases already covered in testFormatFromString - Remove testFormatDescriptions test as it's not very useful Addresses review comment: #1094 (comment)

- Remove canCreate property since it's the same as isSupported - Remove description property entirely as it's not used - Fix displayName for RAW format (remove UDIF reference) - Remove checkDiskutilASIFSupport helper function Addresses review comments: - #1094 (comment) - #1094 (comment) - #1094 (comment)

- Simplify ArgumentParser help text to let it show possible values automatically - Remove canCreate validation since property was removed - Simplify error message for unsupported disk formats Addresses review comment: #1094 (comment)

- Add validation to ensure ASIF disk format is supported on current system - Check disk format compatibility before attempting to run VM Addresses review comment: #1094 (comment)

- Add diskFormatLabelAnnotation constant in Manifest.swift - Use org.cirruslabs.tart.disk.format namespace for consistency - Use variable shadowing instead of new variable name for labels Addresses review comment: #1094 (comment)

- Remove .uncached caching mode for ASIF disks - Use default caching logic for all disk formats - Testing shows .cached mode works fine on macOS 26.0 Addresses review comment: #1094 (comment)

- Use guard let instead of nested if let for better readability - Reduce nesting in resizeASIFDisk function - Improve error handling flow Addresses review comment: #1094 (comment)

Sources/tart/VM.swift

Sources/tart/OCI/Manifest.swift

edigaryev · 2025-06-19T13:47:53Z

@fkorotkov please take a look at the review comments once more.

Some of them were not addressed, for example, #1094 (comment).

Add support for --disk-format argument to specify disk image format when creating VMs with from_ipsw or from_iso. Changes: - Add DiskFormat field to Config struct with validation - Support 'raw' (default) and 'asif' disk formats - Pass --disk-format argument to tart create command - Update HCL2 specification for new field - Add comprehensive documentation - Include example configuration demonstrating usage ASIF (Apple Sparse Image Format) provides better performance but requires macOS 15+ for usage and macOS 26+ for creation. Implements support for cirruslabs/tart#1094

* feat: Add disk_format support for tart create command Add support for --disk-format argument to specify disk image format when creating VMs with from_ipsw or from_iso. Changes: - Add DiskFormat field to Config struct with validation - Support 'raw' (default) and 'asif' disk formats - Pass --disk-format argument to tart create command - Update HCL2 specification for new field - Add comprehensive documentation - Include example configuration demonstrating usage ASIF (Apple Sparse Image Format) provides better performance but requires macOS 15+ for usage and macOS 26+ for creation. Implements support for cirruslabs/tart#1094 * fix: Skip disk resizing for ASIF disks ASIF disks should not be resized using file truncation or in-guest partition resizing. Instead, they should be resized using diskutil on the host (handled by tart set --disk-size command). Changes: - Skip growDisk() operation for ASIF disks in step_disk_file_prepare.go - Skip in-guest partition resizing for ASIF disks in step_disk_resize.go - Add informative messages explaining why resizing is skipped This prevents errors when trying to resize ASIF disk images and ensures proper disk management for the ASIF format. * Update docs/builders/tart.mdx Co-authored-by: Nikolay Edigaryev <edigaryev@gmail.com> * resize a VM via `tart set` * review comments * Fix import errors (#203) * ASIF support PR improvements (#204) * $ make generate * Don't forget to set statekey.DiskChanged --------- Co-authored-by: Nikolay Edigaryev <edigaryev@gmail.com> Co-authored-by: Brian Michel <brian.michel@gmail.com>

feat: Add disk image format selection with ASIF support

b7f0c5e

fkorotkov force-pushed the feature/disk-format-selection branch from 8453203 to b7f0c5e Compare June 14, 2025 17:41

fkorotkov added 2 commits June 14, 2025 15:14

fixed goreleaser-pro

9a342fe

fkorotkov commented Jun 15, 2025

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fkorotkov added 2 commits June 14, 2025 21:53

Update goreleaser installation to use tap-specific formula

c5d1a0c

Change from 'brew install --cask goreleaser-pro' to 'brew install --cask goreleaser/tap/goreleaser-pro' for proper installation from the official goreleaser tap.

Remove VS Code configuration and add to gitignore

110a23e

- Remove .vscode/launch.json from repository - Add .vscode/ to .gitignore to prevent VS Code settings from being tracked

fkorotkov marked this pull request as ready for review June 15, 2025 01:58

fkorotkov requested a review from edigaryev as a code owner June 15, 2025 01:58

edigaryev reviewed Jun 17, 2025

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Sources/tart/VMDirectory+OCI.swift Outdated Show resolved Hide resolved

fkorotkov and others added 10 commits June 17, 2025 11:11

Update Sources/tart/Commands/Create.swift

e8a418a

Co-authored-by: Nikolay Edigaryev <edigaryev@gmail.com>

Update Sources/tart/DiskImageFormat.swift

89a3ef2

Co-authored-by: Nikolay Edigaryev <edigaryev@gmail.com>

Update Sources/tart/DiskImageFormat.swift

d2a345a

Co-authored-by: Nikolay Edigaryev <edigaryev@gmail.com>

Update Create command validation and help text

deb10dd

- Simplify ArgumentParser help text to let it show possible values automatically - Remove canCreate validation since property was removed - Simplify error message for unsupported disk formats Addresses review comment: #1094 (comment)

Add disk format validation to Run command

0a01753

- Add validation to ensure ASIF disk format is supported on current system - Check disk format compatibility before attempting to run VM Addresses review comment: #1094 (comment)

Use proper namespaced constant for OCI label

3772e12

- Add diskFormatLabelAnnotation constant in Manifest.swift - Use org.cirruslabs.tart.disk.format namespace for consistency - Use variable shadowing instead of new variable name for labels Addresses review comment: #1094 (comment)

Remove special ASIF caching mode

6f3ba16

- Remove .uncached caching mode for ASIF disks - Use default caching logic for all disk formats - Testing shows .cached mode works fine on macOS 26.0 Addresses review comment: #1094 (comment)

Improve code structure in VMDirectory

bb7ae7c

- Use guard let instead of nested if let for better readability - Reduce nesting in resizeASIFDisk function - Improve error handling flow Addresses review comment: #1094 (comment)

edigaryev self-requested a review June 19, 2025 13:05

edigaryev reviewed Jun 19, 2025

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edigaryev reviewed Jun 19, 2025

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fkorotkov added 2 commits June 19, 2025 10:05

diskFormatLabel

bc74b9b

reverted caching mode

2e121dc

Use PropertyListDecoder

5346769

edigaryev self-requested a review June 19, 2025 14:21

edigaryev approved these changes Jun 19, 2025

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edigaryev merged commit 3a6c5fb into main Jun 19, 2025
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edigaryev deleted the feature/disk-format-selection branch June 19, 2025 14:27

fkorotkov mentioned this pull request Sep 14, 2025

Performance gap: Xcode build inside Tart VM vs Host #1125

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