Merge pull request #7083 from zarvd/build/log/enable=json-format

Add support for JSON-formatted logging

cmd/cloud-controller-manager/app/controllermanager.go

@@ -83,6 +83,8 @@ func NewCloudControllerManagerCommand() *cobra.Command {
  Use: "cloud-controller-manager",
  Long: `The Cloud controller manager is a daemon that embeds the cloud specific control loops shipped with Kubernetes.`,
  Run: func(cmd *cobra.Command, _ []string) {
+ log.Setup(log.OptionsFromCLIFlags(cmd.Flags()))
+ defer log.Flush()
  verflag.PrintAndExitIfRequested("Cloud Provider Azure")
  cliflag.PrintFlags(cmd.Flags())
 
@@ -203,6 +205,8 @@ func NewCloudControllerManagerCommand() *cobra.Command {
  cliflag.PrintSections(cmd.OutOrStdout(), namedFlagSets, cols)
  })
 
+ log.BindCLIFlags(fs)
+
  return cmd
 }
 

cmd/cloud-controller-manager/controller-manager.go

@@ -24,25 +24,19 @@ import (
  "os"
  "time"
 
- "k8s.io/component-base/logs"
  _ "k8s.io/component-base/metrics/prometheus/clientgo" // load all the prometheus client-go plugins
 
  "sigs.k8s.io/cloud-provider-azure/cmd/cloud-controller-manager/app"
+ "sigs.k8s.io/cloud-provider-azure/pkg/log"
  _ "sigs.k8s.io/cloud-provider-azure/pkg/provider"
 )
 
 func main() {
- rand.Seed(time.Now().UnixNano())
+ rand.Seed(time.Now().UnixNano()) // FIXME: should use crypto/rand for better randomness
+ defer log.Flush()
 
  command := app.NewCloudControllerManagerCommand()
 
- // TODO: once we switch everything over to Cobra commands, we can go back to calling
- // utilflag.InitFlags() (by removing its pflag.Parse() call). For now, we have to set the
- // normalize func and add the go flag set by hand.
- // utilflag.InitFlags()
- logs.InitLogs()
- defer logs.FlushLogs()
-
  if err := command.Execute(); err != nil {
  os.Exit(1)
  }

pkg/log/flag.go

@@ -0,0 +1,67 @@
+/*
+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 log
+
+import (
+ "time"
+
+ "github.com/spf13/pflag"
+)
+
+type Format string
+
+const (
+ JSON Format = "json"
+ Text Format = "text"
+)
+
+const (
+ flagLogFormat = "log-format"
+ flagLogFlushFrequency = "log-flush-frequency"
+
+ DefaultFormat = Text
+ DefaultFlushFrequency = 5 * time.Second
+)
+
+func BindCLIFlags(fs *pflag.FlagSet) {
+ fs.String(flagLogFormat, "text", "The log format to use. One of: text, json.")
+ // log-flush-frequency is registered in kubernetes component-base.
+}
+
+type Options struct {
+ Format Format
+ FlushFrequency time.Duration
+}
+
+func OptionsFromCLIFlags(fs *pflag.FlagSet) *Options {
+ var o Options
+
+ o.Format = Format(fs.Lookup(flagLogFormat).Value.String())
+ if o.Format != JSON && o.Format != Text {
+ SetupError("Invalid log format", flagLogFormat, o.Format)
+ o.Format = DefaultFormat
+ }
+
+ freq, err := fs.GetDuration(flagLogFlushFrequency)
+ if err != nil {
+ SetupError("Invalid log flush frequency", flagLogFlushFrequency, err)
+ o.FlushFrequency = DefaultFlushFrequency
+ }
+ o.FlushFrequency = freq
+
+ return &o
+}

pkg/log/logger.go

@@ -20,8 +20,12 @@ import (
  "context"
  "encoding/json"
  "fmt"
+ "log"
+ "log/slog"
+ "os"
 
  "github.com/go-logr/logr"
+ "k8s.io/component-base/logs"
  "k8s.io/klog/v2"
 )
 
@@ -65,3 +69,36 @@ func ValueAsMap(value any) map[string]any {
 
  return rv
 }
+
+// Setup initializes the logging system.
+func Setup(opts *Options) {
+ log.SetOutput(logs.KlogWriter{})
+ log.SetFlags(0)
+ klog.StartFlushDaemon(opts.FlushFrequency)
+
+ if opts.Format != JSON {
+ return
+ }
+
+ logger := slog.New(NewJSONHandler(os.Stdout, &slog.HandlerOptions{
+ Level: slog.Level(-127), // Set to minimum level; actual filtering is handled by klog.V(N)
+ AddSource: true,
+ ReplaceAttr: func(_ []string, attr slog.Attr) slog.Attr {
+ switch attr.Key {
+ case slog.TimeKey:
+ // Avoid non-deterministic time field
+ return slog.Attr{}
+ default:
+ return attr
+ }
+ },
+ }))
+
+ slog.SetDefault(logger)
+ klog.SetSlogLogger(logger)
+}
+
+// Flush flushes logs immediately.
+func Flush() {
+ klog.Flush()
+}

pkg/log/slog.go

@@ -0,0 +1,65 @@
+/*
+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 log
+
+import (
+ "context"
+ "io"
+ "log/slog"
+)
+
+const (
+ TimeKey = slog.TimeKey
+ LevelKey = slog.LevelKey
+ VerbosityKey = "v"
+)
+
+type SLogJSONHandler struct {
+ handler *slog.JSONHandler
+}
+
+func NewJSONHandler(w io.Writer, opts *slog.HandlerOptions) *SLogJSONHandler {
+ return &SLogJSONHandler{
+ handler: slog.NewJSONHandler(w, opts),
+ }
+}
+
+func (h *SLogJSONHandler) Enabled(ctx context.Context, level slog.Level) bool {
+ return h.handler.Enabled(ctx, level)
+}
+
+func (h *SLogJSONHandler) Handle(ctx context.Context, record slog.Record) error {
+ // Extract verbosity from negative log levels and set it as an attribute.
+ // This is necessary because slog will convert negative levels to DEBUG+N.
+ if record.Level < 0 {
+ verbosity := int(-record.Level)
+ record.Level = slog.LevelInfo
+ record.AddAttrs(slog.Int(VerbosityKey, verbosity))
+ } else {
+ record.AddAttrs(slog.Int(VerbosityKey, 0))
+ }
+
+ return h.handler.Handle(ctx, record)
+}
+
+func (h *SLogJSONHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+ return h.handler.WithAttrs(attrs)
+}
+
+func (h *SLogJSONHandler) WithGroup(name string) slog.Handler {
+ return h.handler.WithGroup(name)
+}

pkg/log/std.go

@@ -0,0 +1,25 @@
+/*
+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 log
+
+import (
+ "log/slog"
+)
+
+func SetupError(msg string, args ...any) {
+ slog.Error(msg, args...)
+}