diff --git a/vendor/go.uber.org/zap/zapcore/hook.go b/vendor/go.uber.org/zap/zapcore/hook.go
new file mode 100644
index 0000000..5db4afb
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/hook.go
@@ -0,0 +1,68 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import "go.uber.org/multierr"
+
+type hooked struct {
+	Core
+	funcs []func(Entry) error
+}
+
+// RegisterHooks wraps a Core and runs a collection of user-defined callback
+// hooks each time a message is logged. Execution of the callbacks is blocking.
+//
+// This offers users an easy way to register simple callbacks (e.g., metrics
+// collection) without implementing the full Core interface.
+func RegisterHooks(core Core, hooks ...func(Entry) error) Core {
+	funcs := append([]func(Entry) error{}, hooks...)
+	return &hooked{
+		Core:  core,
+		funcs: funcs,
+	}
+}
+
+func (h *hooked) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
+	// Let the wrapped Core decide whether to log this message or not. This
+	// also gives the downstream a chance to register itself directly with the
+	// CheckedEntry.
+	if downstream := h.Core.Check(ent, ce); downstream != nil {
+		return downstream.AddCore(ent, h)
+	}
+	return ce
+}
+
+func (h *hooked) With(fields []Field) Core {
+	return &hooked{
+		Core:  h.Core.With(fields),
+		funcs: h.funcs,
+	}
+}
+
+func (h *hooked) Write(ent Entry, _ []Field) error {
+	// Since our downstream had a chance to register itself directly with the
+	// CheckedMessage, we don't need to call it here.
+	var err error
+	for i := range h.funcs {
+		err = multierr.Append(err, h.funcs[i](ent))
+	}
+	return err
+}