Fix null bodies in schema

Signed-off-by: Israel Blancas <iblancasa@gmail.com>

Author: iblancasa

.chloggen/schemagen-null-component-body.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. receiver/otlp)
+component: cmd/schemagen
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Accept components written without a configuration body in the generated Collector configuration schema
+
+# One or more tracking issues or pull requests related to the change
+issues: [15728]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

internal/schemagen/combiner.go

@@ -5,6 +5,7 @@ package schemagen // import "go.opentelemetry.io/collector/internal/schemagen"
 
 import (
 	"fmt"
+	"reflect"
 	"regexp"
 )
 
@@ -99,6 +100,11 @@ func addCollectorComponentPattern(section *JSONSchema, componentType string, sch
 	}
 
 	patternSchema := cloneOrEmptySchema(schema)
+	if schema != nil && !reflect.DeepEqual(*schema, JSONSchema{}) {
+		patternSchema = &JSONSchema{
+			AnyOf: []*JSONSchema{patternSchema, {Type: "null"}},
+		}
+	}
 	if deprecated {
 		patternSchema.Deprecated = true
 	}

internal/schemagen/combiner_test.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/santhosh-tekuri/jsonschema/v6"
 	"github.com/stretchr/testify/require"
+	"go.yaml.in/yaml/v3"
 )
 
 func TestCombineCollectorSchema_LayoutAndValidation(t *testing.T) {
@@ -173,6 +174,123 @@ func TestCombineCollectorSchema_DeprecatedTypeDuplicatesMainType(t *testing.T) {
 	require.ErrorContains(t, err, `duplicate component identifier "health_check"`)
 }
 
+func TestCombineCollectorSchema_NullComponentBodyIsAccepted(t *testing.T) {
+	t.Parallel()
+
+	schema, err := CombineCollectorSchema(CollectorSchemaParts{
+		Receivers: []CollectorComponentSchema{
+			{
+				Type: "otlp",
+				Schema: &JSONSchema{
+					Type: "object",
+					Properties: map[string]*JSONSchema{
+						"endpoint": {Type: "string"},
+					},
+				},
+			},
+		},
+	})
+	require.NoError(t, err)
+
+	compiled := compileSchema(t, schema)
+
+	require.NoError(t, compiled.Validate(unmarshalJSON(t, `{
+		"receivers": {"otlp": null}
+	}`)))
+
+	require.NoError(t, compiled.Validate(unmarshalYAML(t, "receivers:\n  otlp:\n")))
+
+	require.NoError(t, compiled.Validate(unmarshalJSON(t, `{
+		"receivers": {"otlp/secondary": null}
+	}`)))
+
+	require.NoError(t, compiled.Validate(unmarshalJSON(t, `{
+		"receivers": {"otlp": {"endpoint": "localhost:4317"}}
+	}`)))
+}
+
+func TestCombineCollectorSchema_NullBranchDoesNotSwallowTypeErrors(t *testing.T) {
+	t.Parallel()
+
+	schema, err := CombineCollectorSchema(CollectorSchemaParts{
+		Receivers: []CollectorComponentSchema{
+			{
+				Type: "otlp",
+				Schema: &JSONSchema{
+					Type: "object",
+					Properties: map[string]*JSONSchema{
+						"endpoint": {Type: "string"},
+					},
+					Required: []string{"endpoint"},
+				},
+			},
+		},
+	})
+	require.NoError(t, err)
+
+	compiled := compileSchema(t, schema)
+
+	for name, config := range map[string]string{
+		"scalar body":         `{"receivers": {"otlp": 5}}`,
+		"string body":         `{"receivers": {"otlp": "enabled"}}`,
+		"array body":          `{"receivers": {"otlp": []}}`,
+		"wrong property type": `{"receivers": {"otlp": {"endpoint": 4317}}}`,
+		"missing required":    `{"receivers": {"otlp": {}}}`,
+	} {
+		t.Run(name, func(t *testing.T) {
+			require.Error(t, compiled.Validate(unmarshalJSON(t, config)))
+		})
+	}
+}
+
+func TestCombineCollectorSchema_NilSchemaIsNotWrapped(t *testing.T) {
+	t.Parallel()
+
+	schema, err := CombineCollectorSchema(CollectorSchemaParts{
+		Exporters: []CollectorComponentSchema{
+			{Type: "debug"},
+		},
+	})
+	require.NoError(t, err)
+
+	debug := schema.Properties[string(CollectorSectionExporters)].PatternProperties[collectorComponentPattern("debug")]
+	require.NotNil(t, debug)
+	require.Empty(t, debug.AnyOf)
+
+	data, err := debug.MarshalJSON()
+	require.NoError(t, err)
+	require.JSONEq(t, `true`, string(data))
+
+	compiled := compileSchema(t, schema)
+	require.NoError(t, compiled.Validate(unmarshalJSON(t, `{"exporters": {"debug": null}}`)))
+	require.NoError(t, compiled.Validate(unmarshalJSON(t, `{"exporters": {"debug": {"verbosity": "detailed"}}}`)))
+}
+
+func TestCombineCollectorSchema_NilSchemaDeprecatedKeepsMarker(t *testing.T) {
+	t.Parallel()
+
+	schema, err := CombineCollectorSchema(CollectorSchemaParts{
+		Extensions: []CollectorComponentSchema{
+			{Type: "health_check", DeprecatedType: "healthcheck"},
+		},
+	})
+	require.NoError(t, err)
+
+	extensions := schema.Properties[string(CollectorSectionExtensions)]
+	deprecatedSchema := extensions.PatternProperties[collectorComponentPattern("healthcheck")]
+	require.NotNil(t, deprecatedSchema)
+	require.True(t, deprecatedSchema.Deprecated)
+	require.Empty(t, deprecatedSchema.AnyOf)
+
+	data, err := deprecatedSchema.MarshalJSON()
+	require.NoError(t, err)
+	require.JSONEq(t, `{"deprecated": true}`, string(data))
+
+	compiled := compileSchema(t, schema)
+	require.NoError(t, compiled.Validate(unmarshalJSON(t, `{"extensions": {"healthcheck": null}}`)))
+	require.NoError(t, compiled.Validate(unmarshalJSON(t, `{"extensions": {"healthcheck/1": {"endpoint": "x"}}}`)))
+}
+
 func compileSchema(t *testing.T, schema *JSONSchema) *jsonschema.Schema {
 	t.Helper()
 
@@ -198,3 +316,12 @@ func unmarshalJSON(t *testing.T, data string) any {
 
 	return value
 }
+
+func unmarshalYAML(t *testing.T, data string) any {
+	t.Helper()
+
+	var value any
+	require.NoError(t, yaml.Unmarshal([]byte(data), &value))
+
+	return value
+}