cleanup: move pkg/ to internal/

The internal/ directory in Go has a special meaning, and indicates that
those packages are not meant for external consumption. Ceph-CSI does
provide public APIs for other projects to consume. There is no plan to
keep the API of the internally used packages stable.

Closes: #903
Signed-off-by: Niels de Vos <ndevos@redhat.com>

internal/util/log.go

@@ -0,0 +1,42 @@
+/*
+Copyright 2019 The Ceph-CSI 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 util
+
+import (
+	"context"
+	"fmt"
+)
+
+type contextKey string
+
+// CtxKey for context based logging
+var CtxKey = contextKey("ID")
+
+// ReqID for logging request ID
+var ReqID = contextKey("Req-ID")
+
+// Log helps in context based logging
+func Log(ctx context.Context, format string) string {
+	id := ctx.Value(CtxKey)
+	if id == nil {
+		return format
+	}
+	a := fmt.Sprintf("ID: %v ", id)
+	reqID := ctx.Value(ReqID)
+	if reqID == nil {
+		return a + format
+	}
+	a += fmt.Sprintf("Req-ID: %v ", reqID)
+	return a + format
+}