feat: support deprecated field for OpenAPI parameters

docs/docs/mapping/customizing_openapi_output.md

@@ -1114,6 +1114,88 @@ definitions:
         type: string
 ```
 
+### Deprecating parameters
 
-{% endraw %}
+With the `enable_field_deprecation` option, OpenAPI parameters will be marked as deprecated based on the protobuf `deprecated` field option. Allowed values are: `true`, `false`.
+
+For example, if you are using `buf`:
 
+```yaml
+version: v1
+plugins:
+  - name: openapiv2
+    out: .
+    opt:
+      - enable_field_deprecation=true
+```
+
+or with `protoc`
+
+```sh
+protoc --openapiv2_out=. --openapiv2_opt=enable_field_deprecation=true ./path/to/file.proto
+```
+
+Input example:
+
+```protobuf
+message SearchRequest {
+  string legacy_filter = 1 [deprecated = true];
+  string query = 2;
+}
+```
+
+Output (excerpt):
+
+```yaml
+paths:
+  /v1/search:
+    get:
+      parameters:
+        - name: legacy_filter
+          in: query
+          required: false
+          type: string
+          deprecated: true
+        - name: query
+          in: query
+          required: false
+          type: string
+```
+
+If you prefer to leave the protobuf definition active, you can use the `field_configuration.deprecated` annotation on the `openapiv2_field` option instead:
+
+```protobuf
+message SearchRequest {
+  string legacy_filter = 1 [
+    (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_field) = {
+      description: "Legacy filter syntax. Prefer the new 'query' field."
+      field_configuration: { deprecated: true }
+    }
+  ];
+  string query = 2;
+}
+```
+
+This keeps the protobuf field untouched but still emits a deprecated parameter in the generated spec:
+
+```yaml
+paths:
+  /v1/search:
+    get:
+      parameters:
+        - name: legacy_filter
+          in: query
+          required: false
+          type: string
+          description: Legacy filter syntax. Prefer the new 'query' field.
+          deprecated: true
+        - name: query
+          in: query
+          required: false
+          type: string
+```
+
+If you set both the protobuf `deprecated = true` option and `field_configuration.deprecated`, the OpenAPI parameter is marked as deprecated regardless of the `enable_field_deprecation` option.
+
+
+{% endraw %}

internal/descriptor/registry.go

@@ -167,6 +167,9 @@ type Registry struct {
 	// enableRpcDeprecation whether to process grpc method's deprecated option
 	enableRpcDeprecation bool
 
+	// enableFieldDeprecation whether to process proto field's deprecated option
+	enableFieldDeprecation bool
+
 	// expandSlashedPathPatterns, if true, for a path parameter carrying a sub-path, described via parameter pattern (i.e.
 	// the pattern contains forward slashes), this will expand the _pattern_ into the URI and will _replace_ the parameter
 	// with new path parameters inferred from patterns wildcards.
@@ -915,6 +918,16 @@ func (r *Registry) GetEnableRpcDeprecation() bool {
 	return r.enableRpcDeprecation
 }
 
+// SetEnableFieldDeprecation sets enableFieldDeprecation
+func (r *Registry) SetEnableFieldDeprecation(enable bool) {
+	r.enableFieldDeprecation = enable
+}
+
+// GetEnableFieldDeprecation returns enableFieldDeprecation
+func (r *Registry) GetEnableFieldDeprecation() bool {
+	return r.enableFieldDeprecation
+}
+
 func (r *Registry) SetExpandSlashedPathPatterns(expandSlashedPathPatterns bool) {
 	r.expandSlashedPathPatterns = expandSlashedPathPatterns
 }

protoc-gen-openapiv2/defs.bzl

@@ -76,6 +76,7 @@ def _run_proto_gen_openapi(
         use_allof_for_refs,
         disable_default_responses,
         enable_rpc_deprecation,
+        enable_field_deprecation,
         expand_slashed_path_patterns,
         preserve_rpc_order,
         generate_x_go_type):
@@ -155,6 +156,9 @@ def _run_proto_gen_openapi(
     if enable_rpc_deprecation:
         args.add("--openapiv2_opt", "enable_rpc_deprecation=true")
 
+    if enable_field_deprecation:
+        args.add("--openapiv2_opt", "enable_field_deprecation=true")
+
     if expand_slashed_path_patterns:
         args.add("--openapiv2_opt", "expand_slashed_path_patterns=true")
 
@@ -271,6 +275,7 @@ def _proto_gen_openapi_impl(ctx):
                     use_allof_for_refs = ctx.attr.use_allof_for_refs,
                     disable_default_responses = ctx.attr.disable_default_responses,
                     enable_rpc_deprecation = ctx.attr.enable_rpc_deprecation,
+                    enable_field_deprecation = ctx.attr.enable_field_deprecation,
                     expand_slashed_path_patterns = ctx.attr.expand_slashed_path_patterns,
                     preserve_rpc_order = ctx.attr.preserve_rpc_order,
                     generate_x_go_type = ctx.attr.generate_x_go_type,
@@ -434,6 +439,11 @@ protoc_gen_openapiv2 = rule(
             mandatory = False,
             doc = "whether to process grpc method's deprecated option.",
         ),
+        "enable_field_deprecation": attr.bool(
+            default = False,
+            mandatory = False,
+            doc = "whether to process proto field's deprecated option.",
+        ),
         "expand_slashed_path_patterns": attr.bool(
             default = False,
             mandatory = False,

protoc-gen-openapiv2/internal/genopenapi/template.go

@@ -345,6 +345,11 @@ func nestedQueryParams(message *descriptor.Message, field *descriptor.Field, pre
 			}
 		}
 
+		// verify if the field is deprecated, either via proto or annotation
+		protoDeprecated := field.GetOptions().GetDeprecated() && reg.GetEnableFieldDeprecation()
+		annotationDeprecated := getFieldConfiguration(reg, field).GetDeprecated()
+		deprecated := protoDeprecated || annotationDeprecated
+
 		param := openapiParameterObject{
 			Description: desc,
 			In:          "query",
@@ -354,6 +359,7 @@ func nestedQueryParams(message *descriptor.Message, field *descriptor.Field, pre
 			Format:      schema.Format,
 			Pattern:     schema.Pattern,
 			Required:    required,
+			Deprecated:  deprecated,
 			UniqueItems: schema.UniqueItems,
 			extensions:  schema.extensions,
 			Enum:        schema.Enum,
@@ -1454,18 +1460,26 @@ func renderServices(services []*descriptor.Service, paths *openapiPathsObject, r
 					if regExp, ok := pathParamRegexpMap[parameterString]; ok {
 						pattern = regExp
 					}
-					if fc := getFieldConfiguration(reg, parameter.Target); fc != nil {
+					fc := getFieldConfiguration(reg, parameter.Target)
+					if fc != nil {
 						pathParamName := fc.GetPathParamName()
 						if pathParamName != "" && pathParamName != parameterString {
 							pathParamNames["{"+parameterString+"}"] = "{" + pathParamName + "}"
 							parameterString, _, _ = strings.Cut(pathParamName, "=")
 						}
 					}
+
+					// verify if the parameter is deprecated, either via proto or annotation
+					protoDeprecated := parameter.Target.GetOptions().GetDeprecated() && reg.GetEnableFieldDeprecation()
+					annotationDeprecated := fc.GetDeprecated()
+					deprecated := protoDeprecated || annotationDeprecated
+
 					parameters = append(parameters, openapiParameterObject{
 						Name:        parameterString,
 						Description: desc,
 						In:          "path",
 						Required:    true,
+						Deprecated:  deprecated,
 						Default:     defaultValue,
 						// Parameters in gRPC-Gateway can only be strings?
 						Type:             paramType,