Add new log format that is compatible with Kubernetes

Fluentd configuration uses 'log' for the log message
while containerd uses 'msg'. Since we can't have a single
JSON format for both, add another log format and make
debug log configurable.

PiperOrigin-RevId: 219729658
Change-Id: I2a6afc4034d893ab90bafc63b394c4fb62b2a7a0

2 files changed, 48 insertions, 0 deletions

diff --git a/pkg/log/BUILD b/pkg/log/BUILD
index bf85b4494..94ac66db3 100644
--- a/pkg/log/BUILD
+++ b/pkg/log/BUILD
@@ -8,6 +8,7 @@ go_library(
         "glog.go",
         "glog_unsafe.go",
         "json.go",
+        "json_k8s.go",
         "log.go",
     ],
     importpath = "gvisor.googlesource.com/gvisor/pkg/log",
diff --git a/pkg/log/json_k8s.go b/pkg/log/json_k8s.go
new file mode 100644
index 000000000..9c2f8d2b7
--- /dev/null
+++ b/pkg/log/json_k8s.go
@@ -0,0 +1,47 @@
+// Copyright 2018 Google LLC
+//
+// 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 (
+	"encoding/json"
+	"fmt"
+	"time"
+)
+
+type k8sJSONLog struct {
+	Log   string    `json:"log"`
+	Level Level     `json:"level"`
+	Time  time.Time `json:"time"`
+}
+
+// K8sJSONEmitter logs messages in json format that is compatible with
+// Kubernetes fluent configuration.
+type K8sJSONEmitter struct {
+	Writer
+}
+
+// Emit implements Emitter.Emit.
+func (e K8sJSONEmitter) Emit(level Level, timestamp time.Time, format string, v ...interface{}) {
+	j := k8sJSONLog{
+		Log:   fmt.Sprintf(format, v...),
+		Level: level,
+		Time:  timestamp,
+	}
+	b, err := json.Marshal(j)
+	if err != nil {
+		panic(err)
+	}
+	e.Writer.Write(b)
+}