structured-logging: enable KobjSlice usage and warn Kobjs usage

add explicit flag for deprecations check

logcheck/pkg/logcheck.go

@@ -37,6 +37,7 @@ const (
 	contextualCheck    = "contextual"
 	withHelpersCheck   = "with-helpers"
 	verbosityZeroCheck = "verbosity-zero"
+	deprecationsCheck  = "deprecations"
 )
 
 type checks map[string]*bool
@@ -59,6 +60,7 @@ func Analyser() *analysis.Analyzer {
 			contextualCheck:    new(bool),
 			withHelpersCheck:   new(bool),
 			verbosityZeroCheck: new(bool),
+			deprecationsCheck:  new(bool),
 		},
 	}
 	c.fileOverrides.validChecks = map[string]bool{}
@@ -73,6 +75,7 @@ klog methods (Info, Infof, Error, Errorf, Warningf, etc).`)
 	logcheckFlags.BoolVar(c.enabled[contextualCheck], prefix+contextualCheck, false, `When true, logcheck will only allow log calls for contextual logging (retrieving a Logger from klog or the context and logging through that) and warn about all others.`)
 	logcheckFlags.BoolVar(c.enabled[withHelpersCheck], prefix+withHelpersCheck, false, `When true, logcheck will warn about direct calls to WithName, WithValues and NewContext.`)
 	logcheckFlags.BoolVar(c.enabled[verbosityZeroCheck], prefix+verbosityZeroCheck, true, `When true, logcheck will check whether the parameter for V() is 0.`)
+	logcheckFlags.BoolVar(c.enabled[deprecationsCheck], prefix+deprecationsCheck, true, `When true, logcheck will analyze the usage of deprecated Klog function calls.`)
 	logcheckFlags.Var(&c.fileOverrides, "config", `A file which overrides the global settings for checks on a per-file basis via regular expressions.`)
 
 	// Use env variables as defaults. This is necessary when used as plugin
@@ -149,6 +152,17 @@ func checkForFunctionExpr(fexpr *ast.CallExpr, pass *analysis.Pass, c *config) {
 				return
 			}
 
+			// Check for Deprecated function usage
+			if c.isEnabled(deprecationsCheck, filename) {
+				message, deprecatedUse := isDeprecatedContextualCall(fName)
+				if deprecatedUse {
+					pass.Report(analysis.Diagnostic{
+						Pos:     fun.Pos(),
+						Message: message,
+					})
+				}
+			}
+
 			// Matching if any unstructured logging function is used.
 			if c.isEnabled(structuredCheck, filename) && isUnstructured(fName) {
 				pass.Report(analysis.Diagnostic{
@@ -301,6 +315,18 @@ func isUnstructured(fName string) bool {
 	return false
 }
 
+func isDeprecatedContextualCall(fName string) (message string, deprecatedUse bool) {
+	deprecatedContextualLogHelper := map[string]string{
+		"KObjs": "KObjSlice",
+	}
+	var replacementFunction string
+	if replacementFunction, deprecatedUse = deprecatedContextualLogHelper[fName]; deprecatedUse {
+		message = fmt.Sprintf(`Detect usage of deprecated helper "%s". Please switch to "%s" instead.`, fName, replacementFunction)
+		return
+	}
+	return
+}
+
 func isContextualCall(fName string) bool {
 	// List of klog functions we still want to use after migration to
 	// contextual logging. This is an allow list, so any new acceptable
@@ -315,6 +341,7 @@ func isContextualCall(fName string) bool {
 		"FromContext",
 		"KObj",
 		"KObjs",
+		"KObjSlice",
 		"KRef",
 		"LoggerWithName",
 		"LoggerWithValues",

logcheck/testdata/src/k8s.io/klog/v2/klog.go

@@ -221,6 +221,11 @@ func KObjs(obj interface{}) interface{} {
 	return nil
 }
 
+// KObjSlice emulatess klog.KObjSlice
+func KObjSlice(obj interface{}) interface{} {
+	return nil
+}
+
 func KRef(namespace, name string) interface{} {
 	return nil
 }

logcheck/testdata/src/onlyAllowContextual/onlyAllowContextual.go

@@ -26,7 +26,9 @@ import (
 )
 
 func doNotAlllowKlog() {
-	klog.InfoS("test log")       // want `function "InfoS" should not be used, convert to contextual logging`
-	klog.ErrorS(nil, "test log") // want `function "ErrorS" should not be used, convert to contextual logging`
-	klog.V(1).Infof("test log")  // want `function "V" should not be used, convert to contextual logging` `function "Infof" should not be used, convert to contextual logging`
+	klog.InfoS("test log")                         // want `function "InfoS" should not be used, convert to contextual logging`
+	klog.ErrorS(nil, "test log")                   // want `function "ErrorS" should not be used, convert to contextual logging`
+	klog.V(1).Infof("test log")                    // want `function "V" should not be used, convert to contextual logging` `function "Infof" should not be used, convert to contextual logging`
+	klog.KObjs(nil)                                // want `Detect usage of deprecated helper "KObjs". Please switch to "KObjSlice" instead.`
+	klog.InfoS("test log", "key", klog.KObjs(nil)) // want `function "InfoS" should not be used, convert to contextual logging` `Detect usage of deprecated helper "KObjs". Please switch to "KObjSlice" instead.`
 }

logcheck/testdata/src/onlyAllowContextual/whitelistedKlog.go

@@ -27,7 +27,7 @@ import (
 
 func allowKlog() {
 	klog.KObj(nil)
-	klog.KObjs(nil)
+	klog.KObjSlice(nil)
 	klog.KRef("", "")
 	klog.FromContext(nil)
 	klog.TODO()