✨ util: Warning handler that discards messages that match a regular expression (#11179)

* ✨ util: Warning handler that discards messages that match a regular expression

* fixup! ✨ util: Warning handler that discards messages that match a regular expression

Remove deduplication. As a side-effect, simplify the implementation.

* fixup! ✨ util: Warning handler that discards messages that match a regular expression

Fix the test of an uninitialized handler, so that the logger is exercised.

* fixup! ✨ util: Warning handler that discards messages that match a regular expression

Split conflated test case into two independent test cases

Author: dlipovetsky

util/apiwarnings/doc.go

@@ -0,0 +1,18 @@
+/*
+Copyright 2024 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 apiwarnings defines warning handlers used with API clients.
+package apiwarnings

util/apiwarnings/handler.go

@@ -0,0 +1,51 @@
+/*
+Copyright 2024 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 apiwarnings
+
+import (
+	"regexp"
+
+	"github.com/go-logr/logr"
+)
+
+// DiscardMatchingHandler is a handler that discards API server warnings
+// whose message matches any user-defined regular expressions, but otherwise
+// logs warnings to the user-defined logger.
+type DiscardMatchingHandler struct {
+	// Logger is used to log responses with the warning header.
+	Logger logr.Logger
+
+	// Expressions is a slice of regular expressions used to discard warnings.
+	// If the warning message matches any expression, it is not logged.
+	Expressions []regexp.Regexp
+}
+
+// HandleWarningHeader handles logging for responses from API server that are
+// warnings with code being 299 and uses a logr.Logger for its logging purposes.
+func (h *DiscardMatchingHandler) HandleWarningHeader(code int, _, message string) {
+	if code != 299 || message == "" {
+		return
+	}
+
+	for _, exp := range h.Expressions {
+		if exp.MatchString(message) {
+			return
+		}
+	}
+
+	h.Logger.Info(message)
+}

util/apiwarnings/handler_test.go

@@ -0,0 +1,97 @@
+/*
+Copyright 2024 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 apiwarnings
+
+import (
+	"regexp"
+	"testing"
+
+	"github.com/go-logr/logr/funcr"
+	. "github.com/onsi/gomega"
+)
+
+func TestDiscardMatchingHandler(t *testing.T) {
+	tests := []struct {
+		name        string
+		code        int
+		message     string
+		expressions []regexp.Regexp
+		wantLogged  bool
+	}{
+		{
+			name:       "log, if no expressions are defined",
+			code:       299,
+			message:    "non-matching warning",
+			wantLogged: true,
+		},
+		{
+			name:        "log, if warning does not match any expression",
+			code:        299,
+			message:     "non-matching warning",
+			expressions: []regexp.Regexp{},
+			wantLogged:  true,
+		},
+		{
+			name:    "do not log, if warning matches at least one expression",
+			code:    299,
+			message: "matching warning",
+			expressions: []regexp.Regexp{
+				*regexp.MustCompile("^matching.*"),
+			},
+			wantLogged: false,
+		},
+		{
+			name:        "do not log, if code is not 299",
+			code:        0,
+			message:     "warning",
+			expressions: []regexp.Regexp{},
+			wantLogged:  false,
+		},
+		{
+			name:        "do not log, if message is empty",
+			code:        299,
+			message:     "",
+			expressions: []regexp.Regexp{},
+			wantLogged:  false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			g := NewWithT(t)
+			logged := false
+			h := DiscardMatchingHandler{
+				Logger: funcr.New(func(_, _ string) {
+					logged = true
+				},
+					funcr.Options{},
+				),
+				Expressions: tt.expressions,
+			}
+			h.HandleWarningHeader(tt.code, "", tt.message)
+			g.Expect(logged).To(Equal(tt.wantLogged))
+		})
+	}
+}
+
+func TestDiscardMatchingHandler_uninitialized(t *testing.T) {
+	g := NewWithT(t)
+	h := DiscardMatchingHandler{}
+	g.Expect(func() {
+		// Together, the code and message value ensure that the handler logs the message.
+		h.HandleWarningHeader(299, "", "example")
+	}).ToNot(Panic())
+}