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

internal/projectconfig/build.go

@@ -13,7 +13,7 @@ type CheckConfig struct {
 	// Skip indicates whether the %check section should be disabled for this component.
 	Skip bool `toml:"skip,omitempty" json:"skip,omitempty" jsonschema:"title=Skip check,description=Disables the %check section by prepending 'exit 0' when set to true"`
 	// SkipReason provides a required justification when Skip is true.
-	SkipReason string `toml:"skip_reason,omitempty" json:"skipReason,omitempty" jsonschema:"title=Skip reason,description=Required justification for skipping the %check section"`
+	SkipReason string `toml:"skip_reason,omitempty" json:"skipReason,omitempty" jsonschema:"title=Skip reason,description=Required justification for skipping the %check section" fingerprint:"-"`
 }
 
 // Validate checks that required fields are set when Skip is true.
@@ -43,27 +43,27 @@ type ComponentBuildConfig struct {
 	// Check section configuration.
 	Check CheckConfig `toml:"check,omitempty" json:"check,omitempty" jsonschema:"title=Check configuration,description=Configuration for the %check section"`
 	// Failure configuration and policy for this component's build.
-	Failure ComponentBuildFailureConfig `toml:"failure,omitempty" json:"failure,omitempty" jsonschema:"title=Build failure configuration,description=Configuration and policy regarding build failures for this component."`
+	Failure ComponentBuildFailureConfig `toml:"failure,omitempty" json:"failure,omitempty" jsonschema:"title=Build failure configuration,description=Configuration and policy regarding build failures for this component." fingerprint:"-"`
 	// Hints for how or when to build the component; must not be required for correctness of builds.
-	Hints ComponentBuildHints `toml:"hints,omitempty" json:"hints,omitempty" jsonschema:"title=Build hints,description=Non-essential hints for how or when to build the component."`
+	Hints ComponentBuildHints `toml:"hints,omitempty" json:"hints,omitempty" jsonschema:"title=Build hints,description=Non-essential hints for how or when to build the component." fingerprint:"-"`
 }
 
 // ComponentBuildFailureConfig encapsulates configuration and policy regarding a component's
 // build failure.
 type ComponentBuildFailureConfig struct {
 	// Expected indicates that this component is expected to fail building. This is intended to be used as a temporary
 	// marker for components that are expected to fail until they can be fixed.
-	Expected bool `toml:"expected,omitempty" json:"expected,omitempty" jsonschema:"title=Expected failure,description=Indicates that this component is expected to fail building."`
+	Expected bool `toml:"expected,omitempty" json:"expected,omitempty" jsonschema:"title=Expected failure,description=Indicates that this component is expected to fail building." fingerprint:"-"`
 	// ExpectedReason provides a required justification when Expected is true.
-	ExpectedReason string `toml:"expected-reason,omitempty" json:"expectedReason,omitempty" jsonschema:"title=Expected failure reason,description=Required justification for why this component is expected to fail building."`
+	ExpectedReason string `toml:"expected-reason,omitempty" json:"expectedReason,omitempty" jsonschema:"title=Expected failure reason,description=Required justification for why this component is expected to fail building." fingerprint:"-"`
 }
 
 // ComponentBuildHints encapsulates non-essential hints for how or when to build a component.
 // These are not required for correctness of builds, but may be used by tools to provide guidance
 // or optimizations.
 type ComponentBuildHints struct {
 	// Expensive indicates that building this component is relatively expensive compared to the rest of the distro.
-	Expensive bool `toml:"expensive,omitempty" json:"expensive,omitempty" jsonschema:"title=Expensive to build,description=Indicates that building this component is expensive and should be carefully considered when scheduling."`
+	Expensive bool `toml:"expensive,omitempty" json:"expensive,omitempty" jsonschema:"title=Expensive to build,description=Indicates that building this component is expensive and should be carefully considered when scheduling." fingerprint:"-"`
 }
 
 // Validate checks that the build configuration is valid.

internal/projectconfig/component.go

@@ -49,7 +49,7 @@ type Origin struct {
 // SourceFileReference encapsulates a reference to a specific source file artifact.
 type SourceFileReference struct {
 	// Reference to the component to which the source file belongs.
-	Component ComponentReference `toml:"-" json:"-"`
+	Component ComponentReference `toml:"-" json:"-" fingerprint:"-"`
 
 	// Name of the source file; must be non-empty.
 	Filename string `toml:"filename" json:"filename"`
@@ -61,7 +61,7 @@ type SourceFileReference struct {
 	HashType fileutils.HashType `toml:"hash-type,omitempty" json:"hashType,omitempty"`
 
 	// Origin for this source file. When omitted, the file is resolved via the lookaside cache.
-	Origin Origin `toml:"origin,omitempty" json:"origin,omitempty"`
+	Origin Origin `toml:"origin,omitempty" json:"origin,omitempty" fingerprint:"-"`
 }
 
 // Defines a component group. Component groups are logical groupings of components (see [ComponentConfig]).
@@ -111,11 +111,11 @@ func (g ComponentGroupConfig) WithAbsolutePaths(referenceDir string) ComponentGr
 // Defines a component.
 type ComponentConfig struct {
 	// The component's name; not actually present in serialized files.
-	Name string `toml:"-" json:"name" table:",sortkey"`
+	Name string `toml:"-" json:"name" table:",sortkey" fingerprint:"-"`
 
 	// Reference to the source config file that this definition came from; not present
 	// in serialized files.
-	SourceConfigFile *ConfigFile `toml:"-" json:"-" table:"-"`
+	SourceConfigFile *ConfigFile `toml:"-" json:"-" table:"-" fingerprint:"-"`
 
 	// Where to get its spec and adjacent files from.
 	Spec SpecSource `toml:"spec,omitempty" json:"spec,omitempty" jsonschema:"title=Spec,description=Identifies where to find the spec for this component"`

internal/projectconfig/distro.go

@@ -18,7 +18,7 @@ type DistroReference struct {
 	// Version of the referenced distro.
 	Version string `toml:"version,omitempty" json:"version,omitempty" jsonschema:"title=Version,description=Version of the referenced distro"`
 	// Snapshot date/time for source code if specified components will use source as it existed at this time.
-	Snapshot string `toml:"snapshot,omitempty" json:"snapshot,omitempty" jsonschema:"format=date-time,title=Snapshot,description=If specified use source code as it existed at this date/time"`
+	Snapshot string `toml:"snapshot,omitempty" json:"snapshot,omitempty" jsonschema:"format=date-time,title=Snapshot,description=If specified use source code as it existed at this date/time" fingerprint:"-"`
 }
 
 // Implements the [Stringer] interface for [DistroReference].

internal/projectconfig/fingerprint_test.go

@@ -0,0 +1,113 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+package projectconfig_test
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/microsoft/azure-linux-dev-tools/internal/projectconfig"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestAllFingerprintedFieldsHaveDecision verifies that every field in every
+// fingerprinted struct has been consciously categorized as either included
+// (no fingerprint tag) or excluded (`fingerprint:"-"`).
+//
+// This test serves two purposes:
+//  1. It ensures that newly added fields default to **included** in the fingerprint
+//     (the safe default — you get a false positive, never a false negative).
+//  2. It catches accidental removal of `fingerprint:"-"` tags from excluded fields,
+//     since all exclusions are tracked in expectedExclusions.
+func TestAllFingerprintedFieldsHaveDecision(t *testing.T) {
+	// All struct types whose fields participate in component fingerprinting.
+	// When adding a new struct that feeds into the fingerprint, add it here.
+	fingerprintedStructs := []reflect.Type{
+		reflect.TypeFor[projectconfig.ComponentConfig](),
+		reflect.TypeFor[projectconfig.ComponentBuildConfig](),
+		reflect.TypeFor[projectconfig.CheckConfig](),
+		reflect.TypeFor[projectconfig.ComponentBuildFailureConfig](),
+		reflect.TypeFor[projectconfig.ComponentBuildHints](),
+		reflect.TypeFor[projectconfig.ComponentOverlay](),
+		reflect.TypeFor[projectconfig.SpecSource](),
+		reflect.TypeFor[projectconfig.DistroReference](),
+		reflect.TypeFor[projectconfig.SourceFileReference](),
+		reflect.TypeFor[projectconfig.Origin](),
+	}
+
+	// Maps "StructName.FieldName" for every field that should carry a
+	// `fingerprint:"-"` tag. Catches accidental tag removal.
+	//
+	// Each entry documents WHY the field is excluded from the fingerprint:
+	expectedExclusions := map[string]bool{
+		// ComponentConfig.Name — metadata, already the map key in project config.
+		"ComponentConfig.Name": true,
+		// ComponentConfig.SourceConfigFile — internal bookkeeping reference, not a build input.
+		"ComponentConfig.SourceConfigFile": true,
+
+		// ComponentBuildConfig.Failure — CI policy (expected failure tracking), not a build input.
+		"ComponentBuildConfig.Failure": true,
+		// ComponentBuildConfig.Hints — scheduling hints (e.g. expensive), not a build input.
+		"ComponentBuildConfig.Hints": true,
+
+		// CheckConfig.SkipReason — human documentation for why check is skipped, not a build input.
+		"CheckConfig.SkipReason": true,
+
+		// ComponentBuildFailureConfig — entire struct excluded via parent, but individual
+		// fields are also tagged so reflection on the struct alone is consistent.
+		// ComponentBuildFailureConfig.Expected — CI decision about expected failures.
+		"ComponentBuildFailureConfig.Expected": true,
+		// ComponentBuildFailureConfig.ExpectedReason — documentation for expected failure.
+		"ComponentBuildFailureConfig.ExpectedReason": true,
+
+		// ComponentBuildHints — entire struct excluded via parent, fields also tagged.
+		// ComponentBuildHints.Expensive — scheduling hint, does not affect build output.
+		"ComponentBuildHints.Expensive": true,
+
+		// ComponentOverlay.Description — human-readable documentation for the overlay.
+		"ComponentOverlay.Description": true,
+
+		// SourceFileReference.Component — back-reference to parent, not a build input.
+		"SourceFileReference.Component": true,
+
+		// DistroReference.Snapshot — snapshot timestamp is not a build input; the resolved
+		// upstream commit hash (captured separately via SourceIdentity) is what matters.
+		// Excluding this prevents a snapshot bump from marking all upstream components as changed.
+		"DistroReference.Snapshot": true,
+
+		// SourceFileReference.Origin — download location metadata (URI, type), not a build input.
+		// The file content is already captured by Filename + Hash; changing a CDN URL should not
+		// trigger a rebuild.
+		"SourceFileReference.Origin": true,
+	}
+
+	// Collect all actual exclusions found via reflection.
+	actualExclusions := make(map[string]bool)
+
+	for _, st := range fingerprintedStructs {
+		for i := range st.NumField() {
+			field := st.Field(i)
+			key := st.Name() + "." + field.Name
+
+			tag := field.Tag.Get("fingerprint")
+			if tag == "-" {
+				actualExclusions[key] = true
+			}
+		}
+	}
+
+	// Verify every expected exclusion is actually present.
+	for key := range expectedExclusions {
+		assert.Truef(t, actualExclusions[key],
+			"expected field %q to have `fingerprint:\"-\"` tag, but it does not — "+
+				"was the tag accidentally removed?", key)
+	}
+
+	// Verify no unexpected exclusions exist.
+	for key := range actualExclusions {
+		assert.Truef(t, expectedExclusions[key],
+			"field %q has `fingerprint:\"-\"` tag but is not in expectedExclusions — "+
+				"add it to expectedExclusions if the exclusion is intentional", key)
+	}
+}

internal/projectconfig/overlay.go

@@ -17,7 +17,7 @@ type ComponentOverlay struct {
 	// The type of overlay to apply.
 	Type ComponentOverlayType `toml:"type" json:"type" validate:"required" jsonschema:"enum=spec-add-tag,enum=spec-insert-tag,enum=spec-set-tag,enum=spec-update-tag,enum=spec-remove-tag,enum=spec-prepend-lines,enum=spec-append-lines,enum=spec-search-replace,enum=patch-add,enum=patch-remove,enum=file-prepend-lines,enum=file-search-replace,enum=file-add,enum=file-remove,enum=file-rename,title=Overlay type,description=The type of overlay to apply"`
 	// Human readable description of overlay; primarily present to document the need for the change.
-	Description string `toml:"description,omitempty" json:"description,omitempty" jsonschema:"title=Description,description=Human readable description of overlay"`
+	Description string `toml:"description,omitempty" json:"description,omitempty" jsonschema:"title=Description,description=Human readable description of overlay" fingerprint:"-"`
 
 	// For overlays that apply to non-spec files, indicates the filename. For overlays that can
 	// apply to multiple files, supports glob patterns (including globstar).