Merge pull request #23725 from yongtang/23528-journald-sanitize

Sanitize docker labels when used as journald field names

daemon/logger/journald/journald.go

@@ -6,8 +6,8 @@ package journald
 
 import (
 	"fmt"
-	"strings"
 	"sync"
+	"unicode"
 
 	"github.com/Sirupsen/logrus"
 	"github.com/coreos/go-systemd/journal"
@@ -36,6 +36,26 @@ func init() {
 	}
 }
 
+// sanitizeKeyMode returns the sanitized string so that it could be used in journald.
+// In journald log, there are special requirements for fields.
+// Fields must be composed of uppercase letters, numbers, and underscores, but must
+// not start with an underscore.
+func sanitizeKeyMod(s string) string {
+	n := ""
+	for _, v := range s {
+		if 'a' <= v && v <= 'z' {
+			v = unicode.ToUpper(v)
+		} else if ('Z' < v || v < 'A') && ('9' < v || v < '0') {
+			v = '_'
+		}
+		// If (n == "" && v == '_'), then we will skip as this is the beginning with '_'
+		if !(n == "" && v == '_') {
+			n += string(v)
+		}
+	}
+	return n
+}
+
 // New creates a journald logger using the configuration passed in on
 // the context.
 func New(ctx logger.Context) (logger.Logger, error) {
@@ -61,7 +81,7 @@ func New(ctx logger.Context) (logger.Logger, error) {
 		"CONTAINER_NAME":    name,
 		"CONTAINER_TAG":     tag,
 	}
-	extraAttrs := ctx.ExtraAttributes(strings.ToTitle)
+	extraAttrs := ctx.ExtraAttributes(sanitizeKeyMod)
 	for k, v := range extraAttrs {
 		vars[k] = v
 	}

daemon/logger/journald/journald_test.go

@@ -0,0 +1,23 @@
+// +build linux
+
+package journald
+
+import (
+	"testing"
+)
+
+func TestSanitizeKeyMod(t *testing.T) {
+	entries := map[string]string{
+		"io.kubernetes.pod.name":      "IO_KUBERNETES_POD_NAME",
+		"io?.kubernetes.pod.name":     "IO__KUBERNETES_POD_NAME",
+		"?io.kubernetes.pod.name":     "IO_KUBERNETES_POD_NAME",
+		"io123.kubernetes.pod.name":   "IO123_KUBERNETES_POD_NAME",
+		"_io123.kubernetes.pod.name":  "IO123_KUBERNETES_POD_NAME",
+		"__io123_kubernetes.pod.name": "IO123_KUBERNETES_POD_NAME",
+	}
+	for k, v := range entries {
+		if sanitizeKeyMod(k) != v {
+			t.Fatalf("Failed to sanitize %s, got %s, expected %s", k, sanitizeKeyMod(k), v)
+		}
+	}
+}