Wrapped with Conflicting markers

Author: krishagarwal278

docs/linters.md

@@ -4,6 +4,7 @@
 - [Conditions](#conditions) - Checks that `Conditions` fields are correctly formatted
 - [CommentStart](#commentstart) - Ensures comments start with the serialized form of the type
 - [ConflictingMarkers](#conflictingmarkers) - Detects mutually exclusive markers on the same field
+- [DefaultOrRequired](#defaultorrequired) - Ensures fields marked as required do not have default values
 - [DuplicateMarkers](#duplicatemarkers) - Checks for exact duplicates of markers
 - [ForbiddenMarkers](#forbiddenmarkers) - Checks that no forbidden markers are present on types/fields.
 - [Integers](#integers) - Validates usage of supported integer types
@@ -139,6 +140,37 @@ lintersConfig:
 
 The linter does not provide automatic fixes as it cannot determine which conflicting marker should be removed.
 
+## DefaultOrRequired
+
+The `defaultorrequired` linter checks that fields marked as required do not have default values applied.
+
+A field cannot be both required and have a default value, as these are conflicting concepts:
+- A **required** field must be provided by the user and cannot be omitted
+- A **default** value is used when a field is not provided
+
+This linter helps prevent common configuration errors where a field is marked as required but also has a default value, which creates ambiguity about whether the field truly needs to be provided by the user.
+
+### Example
+
+The following will be flagged by the linter:
+
+```go
+type MyStruct struct {
+	// +required
+	// +default:=value
+	ConflictedField string `json:"conflictedField"` // Error: field cannot have both a default value and be marked as required
+}
+```
+
+The linter also detects conflicts with:
+- `+required` 
+- `+default`
+- `+k8s:required`
+- `+kubebuilder:validation:Required`
+- `+kubebuilder:default`
+
+This linter is enabled by default and helps ensure that API designs are consistent and unambiguous about whether fields are truly required or have default values.
+
 ## DuplicateMarkers
 
 The duplicatemarkers linter checks for exact duplicates of markers for types and fields.

pkg/analysis/conflictingmarkers/analyzer.go

@@ -36,6 +36,13 @@ type analyzer struct {
 }
 
 func newAnalyzer(cfg *ConflictingMarkersConfig) *analysis.Analyzer {
+	return NewAnalyzer(cfg)
+}
+
+// NewAnalyzer creates a new conflictingmarkers analyzer with the given configuration.
+// This function is exported so that other linters can use conflictingmarkers functionality
+// with custom configurations.
+func NewAnalyzer(cfg *ConflictingMarkersConfig) *analysis.Analyzer {
 	if cfg == nil {
 		cfg = &ConflictingMarkersConfig{}
 	}

pkg/analysis/defaultorrequired/analyzer.go

@@ -0,0 +1,50 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package defaultorrequired
+
+import (
+	"golang.org/x/tools/go/analysis"
+	"sigs.k8s.io/kube-api-linter/pkg/analysis/conflictingmarkers"
+	"sigs.k8s.io/kube-api-linter/pkg/markers"
+)
+
+const name = "defaultorrequired"
+
+// newAnalyzer creates a new analyzer that wraps conflictingmarkers with a predefined configuration
+// for checking default and required marker conflicts.
+func newAnalyzer() *analysis.Analyzer {
+	cfg := &conflictingmarkers.ConflictingMarkersConfig{
+		Conflicts: []conflictingmarkers.ConflictSet{
+			{
+				Name: "default_or_required",
+				Sets: [][]string{
+					{markers.DefaultMarker, markers.KubebuilderDefaultMarker},
+					{markers.RequiredMarker, markers.KubebuilderRequiredMarker, markers.K8sRequiredMarker},
+				},
+				Description: "A field with a default value cannot be required. A required field must be provided by the user, so a default value is not meaningful.",
+			},
+		},
+	}
+
+	// Create the underlying conflicting markers analyzer
+	analyzer := conflictingmarkers.NewAnalyzer(cfg)
+
+	// Override the name to match this linter
+	analyzer.Name = name
+	analyzer.Doc = "Checks that fields marked as required do not have default values applied"
+
+	return analyzer
+}

pkg/analysis/defaultorrequired/analyzer_test.go

@@ -0,0 +1,34 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package defaultorrequired_test
+
+import (
+	"testing"
+
+	"golang.org/x/tools/go/analysis/analysistest"
+	"sigs.k8s.io/kube-api-linter/pkg/analysis/defaultorrequired"
+)
+
+func Test(t *testing.T) {
+	testdata := analysistest.TestData()
+
+	analyzer, err := defaultorrequired.Initializer().Init(nil)
+	if err != nil {
+		t.Fatalf("initializing defaultorrequired linter: %v", err)
+	}
+
+	analysistest.Run(t, testdata, analyzer, "a")
+}

pkg/analysis/defaultorrequired/doc.go

@@ -0,0 +1,32 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/*
+Package defaultorrequired provides the defaultorrequired analyzer.
+
+The defaultorrequired analyzer checks that fields marked as required do not have default values applied.
+
+A field cannot be both required and have a default value, as these are conflicting concepts:
+- A required field must be provided by the user and cannot be omitted
+- A default value is used when a field is not provided
+
+For example, the following would be flagged:
+
+	// +kubebuilder:validation:Required
+	// +kubebuilder:default:=value
+	Field string `json:"field"`
+*/
+package defaultorrequired

pkg/analysis/defaultorrequired/initializer.go

@@ -0,0 +1,35 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package defaultorrequired
+
+import (
+	"sigs.k8s.io/kube-api-linter/pkg/analysis/initializer"
+	"sigs.k8s.io/kube-api-linter/pkg/analysis/registry"
+)
+
+func init() {
+	registry.DefaultRegistry().RegisterLinter(Initializer())
+}
+
+// Initializer returns the AnalyzerInitializer for this
+// Analyzer so that it can be added to the registry.
+func Initializer() initializer.AnalyzerInitializer {
+	return initializer.NewInitializer(
+		name,
+		newAnalyzer(),
+		true,
+	)
+}

pkg/analysis/defaultorrequired/testdata/src/a/a.go

@@ -0,0 +1,41 @@
+package a
+
+type Test struct {
+	// This field has both required and default markers - should be flagged
+	// +kubebuilder:validation:Required
+	// +kubebuilder:default:=testValue
+	ConflictedField string `json:"conflictedField"` // want `field Test.ConflictedField has conflicting markers: default_or_required: \{\[kubebuilder:default\], \[kubebuilder:validation:Required\]\}. A field with a default value cannot be required. A required field must be provided by the user, so a default value is not meaningful.`
+
+	// This field has only required marker - should not be flagged
+	// +kubebuilder:validation:Required
+	RequiredOnlyField string `json:"requiredOnlyField"`
+
+	// This field has only default marker - should not be flagged
+	// +kubebuilder:default:=defaultValue
+	DefaultOnlyField string `json:"defaultOnlyField"`
+
+	// This field uses KAL required marker with default - should be flagged
+	// +required
+	// +default:=anotherValue
+	KALConflictedField string `json:"kalConflictedField"` // want `field Test.KALConflictedField has conflicting markers: default_or_required: \{\[default\], \[required\]\}. A field with a default value cannot be required. A required field must be provided by the user, so a default value is not meaningful.`
+
+	// This field uses k8s required marker with kubebuilder default - should be flagged
+	// +k8s:required
+	// +kubebuilder:default:=yetanotherValue
+	K8sConflictedField string `json:"k8sConflictedField"` // want `field Test.K8sConflictedField has conflicting markers: default_or_required: \{\[kubebuilder:default\], \[k8s:required\]\}. A field with a default value cannot be required. A required field must be provided by the user, so a default value is not meaningful.`
+
+	// This field has neither marker - should not be flagged
+	NormalField string `json:"normalField"`
+
+	// Multiple fields to test various combinations
+	ValidField1 string `json:"validField1"` // no markers
+
+	// +required
+	ValidField2 string `json:"validField2"` // only required
+
+	// +kubebuilder:default:=value
+	ValidField3 string `json:"validField3"` // only default
+
+	// +kubebuilder:validation:Required
+	ValidField4 string `json:"validField4"` // only required (kubebuilder format)
+}

pkg/registration/doc.go

@@ -27,6 +27,7 @@ import (
 	_ "sigs.k8s.io/kube-api-linter/pkg/analysis/commentstart"
 	_ "sigs.k8s.io/kube-api-linter/pkg/analysis/conditions"
 	_ "sigs.k8s.io/kube-api-linter/pkg/analysis/conflictingmarkers"
+	_ "sigs.k8s.io/kube-api-linter/pkg/analysis/defaultorrequired"
 	_ "sigs.k8s.io/kube-api-linter/pkg/analysis/duplicatemarkers"
 	_ "sigs.k8s.io/kube-api-linter/pkg/analysis/forbiddenmarkers"
 	_ "sigs.k8s.io/kube-api-linter/pkg/analysis/integers"