Implement handlers to normalise how logging is handled

internal/log/handlers/batch/batch.go

@@ -0,0 +1,33 @@
+package batch
+
+import (
+	j "encoding/json"
+	"io"
+	"os"
+	"sync"
+
+	"github.com/apex/log"
+)
+
+// Default handler outputting to stderr.
+var Default = New(os.Stderr)
+
+// Handler implementation.
+type Handler struct {
+	*j.Encoder
+	mu sync.Mutex
+}
+
+// New handler.
+func New(w io.Writer) *Handler {
+	return &Handler{
+		Encoder: j.NewEncoder(w),
+	}
+}
+
+// HandleLog implements log.Handler.
+func (h *Handler) HandleLog(e *log.Entry) error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return h.Encoder.Encode(e)
+}