logging library up to top level

1 files changed, 43 insertions, 0 deletions

diff --git a/logging/logger.go b/logging/logger.go
new file mode 100644
index 0000000..f80a1ae
--- /dev/null
+++ b/logging/logger.go
@@ -0,0 +1,43 @@
+package logging
+
+import (
+	"os"
+
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
+	"github.com/go-kit/log/term"
+)
+
+// Logger records log lines to an output.
+type Logger interface {
+	Log(keyvals ...any) error
+}
+
+// DefaultLoggers produces helpful base loggers for each level.
+//
+// They write logfmt to standard out, annotated with ANSI colors depending on the level.
+func DefaultLoggers() (debug, info, warn, error Logger) {
+	base := term.NewLogger(os.Stdout, log.NewLogfmtLogger, func(keyvals ...any) term.FgBgColor {
+		for i := 0; i < len(keyvals)-1; i += 2 {
+			if keyvals[i] != "level" {
+				continue
+			}
+
+			switch keyvals[i+1] {
+			case level.DebugValue():
+				return term.FgBgColor{Fg: term.DarkGray}
+			case level.InfoValue():
+				return term.FgBgColor{Fg: term.Green}
+			case level.WarnValue():
+				return term.FgBgColor{Fg: term.Yellow}
+			case level.ErrorValue():
+				return term.FgBgColor{Fg: term.Red}
+			}
+		}
+
+		return term.FgBgColor{}
+	})
+	base = log.NewSyncLogger(base)
+
+	return level.Debug(base), level.Info(base), level.Warn(base), level.Error(base)
+}