all: eliminate usage of global ProxyLogger

So setting up logging for ctrld binary and ctrld packages could be done
more easily, decouple the required setup for interactive vs daemon
running.

This is the first step toward replacing rs/zerolog libary with a
different logging library.

log.go

@@ -3,19 +3,37 @@ package ctrld
 import (
 	"context"
 	"fmt"
-	"io"
-	"sync/atomic"
 
 	"github.com/rs/zerolog"
 )
 
-// ProxyLog emits the log record for proxy operations.
-// The caller should set it only once.
-// DEPRECATED: use ProxyLogger instead.
-var ProxyLog = zerolog.New(io.Discard)
+// LoggerCtxKey is the context.Context key for a logger.
+type LoggerCtxKey struct{}
 
-// ProxyLogger emits the log record for proxy operations.
-var ProxyLogger atomic.Pointer[zerolog.Logger]
+// LoggerCtx returns a context.Context with LoggerCtxKey set.
+func LoggerCtx(ctx context.Context, l *Logger) context.Context {
+	return context.WithValue(ctx, LoggerCtxKey{}, l)
+}
+
+// A Logger provides fast, leveled, structured logging.
+type Logger struct {
+	*zerolog.Logger
+}
+
+var noOpZeroLogger = zerolog.Nop()
+
+// NopLogger returns a logger which all operation are no-op.
+var NopLogger = &Logger{&noOpZeroLogger}
+
+// LoggerFromCtx returns the logger associated with given ctx.
+//
+// If there's no logger, a no-op logger will be returned.
+func LoggerFromCtx(ctx context.Context) *Logger {
+	if logger, ok := ctx.Value(LoggerCtxKey{}).(*Logger); ok && logger != nil {
+		return logger
+	}
+	return NopLogger
+}
 
 // ReqIdCtxKey is the context.Context key for a request id.
 type ReqIdCtxKey struct{}