feat(component): Add deterministic component fingerprints by dmcilvaney · Pull Request #47 · microsoft/azure-linux-dev-tools

dmcilvaney · 2026-03-31T00:53:41Z

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Copilot

Pull request overview

Adds a new internal fingerprinting utility intended to compute deterministic “component fingerprints” from resolved component configuration plus additional build context.

Changes:

Introduces internal/fingerprint package with ComputeIdentity to produce a SHA256-based fingerprint and an inputs breakdown.
Adds a comprehensive test suite covering many config/input variations.
Exports OpenProjectRepo in synthetic history code and adds hashstructure/v2 dependency.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
internal/fingerprint/fingerprint.go	New fingerprint computation logic (config hashing + overlay file hashing + SHA256 combiner).
internal/fingerprint/fingerprint_test.go	New tests asserting determinism and expected sensitivity/insensitivity to various inputs.
internal/fingerprint/doc.go	Package documentation for the new fingerprint module.
internal/app/azldev/core/sources/synthistory.go	Renames `openProjectRepo` to exported `OpenProjectRepo` and updates call site.
go.mod	Adds `github.com/mitchellh/hashstructure/v2` dependency.
go.sum	Adds checksums for the new dependency.

Copilot

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated 5 comments.

Copilot

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated 3 comments.

Copilot

Pull request overview

Copilot reviewed 8 out of 9 changed files in this pull request and generated 3 comments.

Copilot

Pull request overview

Copilot reviewed 8 out of 9 changed files in this pull request and generated 2 comments.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

reubeno

Apart from the individual comments, my main question... what's your thoughts on how we can ensure that this algorithm stays in sync with the component and overlay definitions as the latter evolve?

reubeno · 2026-04-11T00:07:50Z

+	OverlayFileHashes map[string]string `json:"overlayFileHashes,omitempty"`
+	// AffectsCommitCount is the number of "Affects: <component>" commits in the project repo.
+	AffectsCommitCount int `json:"affectsCommitCount"`
+	// Distro is the effective distro name.


Why does this need to be tracked?

reubeno · 2026-04-11T00:09:44Z

+func ComputeIdentity(
+	fs opctx.FS,
+	component projectconfig.ComponentConfig,
+	distroRef projectconfig.DistroReference,


Is this the distro that the component is being built for or the distro that the component's spec may have come from? Can we document and clarify?

It should be the effective distro for the component, ie if one is set, pick that, otherwise the global default.

That said, we can probably drop it to just ReleaseVer, that might be the only bit we really care about.

Copilot

Pull request overview

Copilot reviewed 8 out of 9 changed files in this pull request and generated 1 comment.

Copilot

Pull request overview

Copilot reviewed 8 out of 9 changed files in this pull request and generated 2 comments.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 8 out of 9 changed files in this pull request and generated 4 comments.

Copilot · 2026-04-14T18:22:12Z

 	"github.com/bmatcuk/doublestar/v4"
 	"github.com/brunoga/deep"
+	"github.com/microsoft/azure-linux-dev-tools/internal/global/opctx"
+	"github.com/microsoft/azure-linux-dev-tools/internal/utils/fileutils"
 )


This file uses filepath.Base and fmt.Errorf, but path/filepath and fmt are not imported in the shown import block. As written, this will not compile. Add the missing imports (and keep them grouped consistently with the existing imports).

Copilot · 2026-04-14T18:22:12Z

+		return c.Filename
+	}
+
+	return filepath.Base(c.Source)


This file uses filepath.Base and fmt.Errorf, but path/filepath and fmt are not imported in the shown import block. As written, this will not compile. Add the missing imports (and keep them grouped consistently with the existing imports).

Copilot · 2026-04-14T18:22:12Z

+
+	contentHash, err := fileutils.ComputeFileHash(fs, fileutils.HashTypeSHA256, c.Source)
+	if err != nil {
+		return "", fmt.Errorf("hashing overlay source %#q:\n%w", c.Source, err)


This file uses filepath.Base and fmt.Errorf, but path/filepath and fmt are not imported in the shown import block. As written, this will not compile. Add the missing imports (and keep them grouped consistently with the existing imports).

Copilot · 2026-04-14T18:22:13Z

 	// the config file that defines the overlay.
-	Source string `toml:"source,omitempty" json:"source,omitempty" jsonschema:"title=Source,description=For overlays that require a source file as input, indicates a path to that file; relative paths are relative to the config file that defines the overlay"`
+	// Excluded from fingerprint because it contains an absolute path that varies by checkout
+	// location. Overlay content is hashed separately by [fingerprint.ComputeIdentity].


Similar to SpecSource, the Go doc link [fingerprint.ComputeIdentity] may not resolve from this package/file if fingerprint isn’t an imported identifier here. Consider replacing the bracket-link with plain text or referencing this behavior in internal/fingerprint docs instead.

Suggested change

// location. Overlay content is hashed separately by [fingerprint.ComputeIdentity].

// location. Overlay content is hashed separately by the internal fingerprint computation.

Copilot AI review requested due to automatic review settings March 31, 2026 00:53

Copilot started reviewing on behalf of dmcilvaney March 31, 2026 00:54 View session

dmcilvaney mentioned this pull request Mar 31, 2026

feat(component): Add component change detection #42

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dmcilvaney force-pushed the damcilva/component_change_detection_parts/5 branch from a7d028e to 3fb8df7 Compare March 31, 2026 01:06

Copilot AI review requested due to automatic review settings March 31, 2026 01:07

dmcilvaney force-pushed the damcilva/component_change_detection_parts/5 branch from 3fb8df7 to 759c099 Compare March 31, 2026 01:07

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Comment thread internal/fingerprint/fingerprint.go Outdated

Comment thread internal/fingerprint/fingerprint.go Outdated

Comment thread internal/fingerprint/fingerprint_test.go

Comment thread internal/fingerprint/fingerprint_test.go

Comment thread internal/fingerprint/fingerprint_test.go

dmcilvaney marked this pull request as draft March 31, 2026 01:41

dmcilvaney mentioned this pull request Apr 1, 2026

feat(config): Add fingerprint ignore tags to some config fields #46

Merged

dmcilvaney added 2 commits April 10, 2026 15:26

feat(component): Add deterministic component fingerprints

15dcea7

add explicit check that hash is set for components

94e19ff

dmcilvaney force-pushed the damcilva/component_change_detection_parts/5 branch from 0140c52 to 94e19ff Compare April 10, 2026 22:27

Copilot AI review requested due to automatic review settings April 10, 2026 22:27

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Comment thread internal/fingerprint/fingerprint.go Outdated

Comment thread internal/fingerprint/fingerprint.go

Comment thread internal/fingerprint/fingerprint.go

dmcilvaney added 2 commits April 10, 2026 15:55

feedback: ignore spec dir, use file utils

78e76d5

fix: handle overlay source files better

98422f3

Copilot AI review requested due to automatic review settings April 10, 2026 23:03

feedback: don't need to export repo root func anymore

ce450ef

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Comment thread internal/fingerprint/fingerprint.go

Comment thread internal/fingerprint/fingerprint.go Outdated

Comment thread internal/fingerprint/fingerprint.go Outdated

Copilot started reviewing on behalf of dmcilvaney April 10, 2026 23:13 View session

dmcilvaney added 2 commits April 10, 2026 16:36

fix: handle overlay patch paths

f2c50ee

feedback: force identity, fix comment

cf9d102

Copilot AI review requested due to automatic review settings April 10, 2026 23:43

Copilot started reviewing on behalf of dmcilvaney April 10, 2026 23:45 View session

dmcilvaney marked this pull request as ready for review April 10, 2026 23:48

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Comment thread internal/fingerprint/fingerprint.go

Comment thread internal/projectconfig/specsource.go Outdated

Update internal/projectconfig/specsource.go

26fd8d3

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings April 11, 2026 00:12

reubeno reviewed Apr 11, 2026

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Comment thread internal/fingerprint/fingerprint.go

dmcilvaney added 2 commits April 10, 2026 22:19

feedback: use releasever, move overlay logic

561fb1f

refactor: v2 will not use affects count

354b059

Copilot AI review requested due to automatic review settings April 13, 2026 18:24

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Comment thread internal/fingerprint/fingerprint.go

Comment thread internal/fingerprint/doc.go Outdated

Copilot started reviewing on behalf of dmcilvaney April 13, 2026 18:44 View session

Update internal/fingerprint/doc.go

7faa755

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings April 14, 2026 18:15

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Copilot started reviewing on behalf of dmcilvaney April 14, 2026 20:11 View session

	// location. Overlay content is hashed separately by [fingerprint.ComputeIdentity].
	// location. Overlay content is hashed separately by the internal fingerprint computation.

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dmcilvaney commented Mar 31, 2026

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