Add support for JSON log formatting

- Add log setter for text or JSON log formatting
- Add CLI option "--log-format", accepts "text" or "json"
- Defaults to current "text" logging for compatibility

Additionally:
- Configure `cmd` go.mod to reference registry-scanner locally to support concurrent changes in both modules

Signed-off-by: Michael Pilat <[email protected]>

Author: mikepilat

cmd/main.go

@@ -36,6 +36,7 @@ type ImageUpdaterConfig struct {
 	CheckInterval          time.Duration
 	ArgoClient             argocd.ArgoCD
 	LogLevel               string
+	LogFormat              string
 	KubeClient             *kube.ImageUpdaterKubernetesClient
 	MaxConcurrency         int
 	HealthPort             int

cmd/run.go

@@ -50,6 +50,17 @@ func newRunCommand() *cobra.Command {
 				return err
 			}
 
+			var logFormat log.LogFormat
+			switch cfg.LogFormat {
+			case "text":
+				logFormat = log.LogFormatText
+			case "json":
+				logFormat = log.LogFormatJSON
+			default:
+				return fmt.Errorf("Invalid log format '%s'", cfg.LogFormat)
+			}
+			log.SetLogFormat(logFormat)
+
 			if once {
 				cfg.CheckInterval = 0
 				cfg.HealthPort = 0
@@ -322,6 +333,7 @@ func newRunCommand() *cobra.Command {
 	runCmd.Flags().BoolVar(&cfg.DryRun, "dry-run", false, "run in dry-run mode. If set to true, do not perform any changes")
 	runCmd.Flags().DurationVar(&cfg.CheckInterval, "interval", env.GetDurationVal("IMAGE_UPDATER_INTERVAL", 2*time.Minute), "interval for how often to check for updates")
 	runCmd.Flags().StringVar(&cfg.LogLevel, "loglevel", env.GetStringVal("IMAGE_UPDATER_LOGLEVEL", "info"), "set the loglevel to one of trace|debug|info|warn|error")
+	runCmd.Flags().StringVar(&cfg.LogFormat, "log-format", env.GetStringVal("IMAGE_UPDATER_LOG_FORMAT", "text"), "set the log format to one of text|json")
 	runCmd.Flags().StringVar(&kubeConfig, "kubeconfig", "", "full path to kubernetes client configuration, i.e. ~/.kube/config")
 	runCmd.Flags().IntVar(&cfg.HealthPort, "health-port", 8080, "port to start the health server on, 0 to disable")
 	runCmd.Flags().IntVar(&cfg.MetricsPort, "metrics-port", 8081, "port to start the metrics server on, 0 to disable")

go.mod

@@ -37,7 +37,7 @@ require (
 	dario.cat/mergo v1.0.1 // indirect
 	github.com/Azure/go-ansiterm v0.0.0-20230124172434-306776ec8161 // indirect
 	github.com/MakeNowJust/heredoc v1.0.0 // indirect
-	github.com/Masterminds/semver/v3 v3.3.1 // indirect
+	github.com/Masterminds/semver/v3 v3.4.0 // indirect
 	github.com/Microsoft/go-winio v0.6.2 // indirect
 	github.com/ProtonMail/go-crypto v1.1.6 // indirect
 	github.com/benbjohnson/clock v1.3.0 // indirect
@@ -211,3 +211,5 @@ replace (
 	k8s.io/sample-cli-plugin => k8s.io/sample-cli-plugin v0.32.2
 	k8s.io/sample-controller => k8s.io/sample-controller v0.32.2
 )
+
+replace github.com/argoproj-labs/argocd-image-updater/registry-scanner => ./registry-scanner

go.sum

@@ -10,8 +10,8 @@ github.com/Azure/go-ansiterm v0.0.0-20230124172434-306776ec8161/go.mod h1:xomTg6
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/MakeNowJust/heredoc v1.0.0 h1:cXCdzVdstXyiTqTvfqk9SDHpKNjxuom+DOlyEeQ4pzQ=
 github.com/MakeNowJust/heredoc v1.0.0/go.mod h1:mG5amYoWBHf8vpLOuehzbGGw0EHxpZZ6lCpQ4fNJ8LE=
-github.com/Masterminds/semver/v3 v3.3.1 h1:QtNSWtVZ3nBfk8mAOu/B6v7FMJ+NHTIgUPi7rj+4nv4=
-github.com/Masterminds/semver/v3 v3.3.1/go.mod h1:4V+yj/TJE1HU9XfppCwVMZq3I84lprf4nC11bSS5beM=
+github.com/Masterminds/semver/v3 v3.4.0 h1:Zog+i5UMtVoCU8oKka5P7i9q9HgrJeGzI9SA1Xbatp0=
+github.com/Masterminds/semver/v3 v3.4.0/go.mod h1:4V+yj/TJE1HU9XfppCwVMZq3I84lprf4nC11bSS5beM=
 github.com/Microsoft/go-winio v0.5.2/go.mod h1:WpS1mjBmmwHBEWmogvA2mj8546UReBk4v8QkMxJ6pZY=
 github.com/Microsoft/go-winio v0.6.2 h1:F2VQgta7ecxGYO8k3ZZz3RS8fVIXVxONVUPlNERoyfY=
 github.com/Microsoft/go-winio v0.6.2/go.mod h1:yd8OoFMLzJbo9gZq8j5qaps8bJ9aShtEA8Ipt1oGCvU=
@@ -27,8 +27,6 @@ github.com/alicebob/miniredis/v2 v2.33.0/go.mod h1:MhP4a3EU7aENRi9aO+tHfTBZicLqQ
 github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be h1:9AeTilPcZAjCFIImctFaOjnTIavg87rW78vTPkQqLI8=
 github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be/go.mod h1:ySMOLuWl6zY27l47sB3qLNK6tF2fkHG55UZxx8oIVo4=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
-github.com/argoproj-labs/argocd-image-updater/registry-scanner v0.0.0-20250624020913-398db53f47e4 h1:kDbTmJkeg4Z4JSc6ytEqcpv7PuM9lZJej78yQS+AnfY=
-github.com/argoproj-labs/argocd-image-updater/registry-scanner v0.0.0-20250624020913-398db53f47e4/go.mod h1:5Q9a7RvrHCgwoZDLN9f9YugZfvZuQWSbrMqRQD4IXTM=
 github.com/argoproj/argo-cd/v2 v2.14.15 h1:+rE5bwbCg21mA3ltIvSVI8/KtzRxLLmuDKIyPx93G9k=
 github.com/argoproj/argo-cd/v2 v2.14.15/go.mod h1:O5p0wngJjy8Rg9M2x+JH0ifrmyuI40ui2mxIPKLMbSk=
 github.com/argoproj/gitops-engine v0.7.1-0.20250521000818-c08b0a72c1f1 h1:Ze4U6kV49vSzlUBhH10HkO52bYKAIXS4tHr/MlNDfdU=

registry-scanner/pkg/log/log.go

@@ -61,6 +61,22 @@ func SetLogLevel(logLevel string) error {
 	return nil
 }
 
+type LogFormat int
+
+const (
+	LogFormatText LogFormat = iota
+	LogFormatJSON
+)
+
+func SetLogFormat(logFormat LogFormat) {
+	switch logFormat {
+	case LogFormatText:
+		logger.SetFormatter(&logrus.TextFormatter{DisableColors: disableLogColors()})
+	case LogFormatJSON:
+		logger.SetFormatter(&logrus.JSONFormatter{})
+	}
+}
+
 // WithContext is an alias for NewContext
 func WithContext() *LogContext {
 	return NewContext()

registry-scanner/pkg/log/log_test.go

@@ -1,6 +1,7 @@
 package log
 
 import (
+	"encoding/json"
 	"fmt"
 	"testing"
 
@@ -154,3 +155,31 @@ func Test_LogLevel(t *testing.T) {
 		assert.Error(t, err)
 	})
 }
+
+func Test_LogFormatJSON(t *testing.T) {
+	// We need tracing level
+	Log().SetLevel(logrus.TraceLevel)
+
+	t.Run("Test set text log format", func(t *testing.T) {
+		SetLogFormat(LogFormatText)
+		out, err := fixture.CaptureStdout(func() {
+			WithContext().AddField("foo", "bar").Infof("this is a test")
+		})
+		assert.NoError(t, err)
+		assert.Contains(t, out, "foo=bar")
+		assert.Contains(t, out, "msg=\"this is a test\"")
+	})
+	t.Run("Test set JSON log format", func(t *testing.T) {
+		SetLogFormat(LogFormatJSON)
+		out, err := fixture.CaptureStdout(func() {
+			WithContext().AddField("foo", "bar").Warnf("this is a test")
+		})
+		assert.NoError(t, err)
+
+		var data map[string]any
+		err = json.Unmarshal([]byte(out), &data)
+		assert.NoError(t, err)
+		assert.Equal(t, "bar", data["foo"])
+		assert.Equal(t, "this is a test", data["msg"])
+	})
+}