v2: Logging! (#2831)

* logging: Initial implementation

* logging: More encoder formats, better defaults

* logging: Fix repetition bug with FilterEncoder; add more presets

* logging: DiscardWriter; delete or no-op logs that discard their output

* logging: Add http.handlers.log module; enhance Replacer methods

The Replacer interface has new methods to customize how to handle empty
or unrecognized placeholders. Closes #2815.

* logging: Overhaul HTTP logging, fix bugs, improve filtering, etc.

* logging: General cleanup, begin transitioning to using new loggers

* Fixes after merge conflict

modules/caddyhttp/marshalers.go

@@ -0,0 +1,89 @@
+// Copyright 2015 Matthew Holt and The Caddy 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 caddyhttp
+
+import (
+	"crypto/tls"
+	"net/http"
+
+	"go.uber.org/zap/zapcore"
+)
+
+// LoggableHTTPRequest makes an HTTP request loggable with zap.Object().
+type LoggableHTTPRequest struct{ *http.Request }
+
+// MarshalLogObject satisfies the zapcore.ObjectMarshaler interface.
+func (r LoggableHTTPRequest) MarshalLogObject(enc zapcore.ObjectEncoder) error {
+	enc.AddString("method", r.Method)
+	enc.AddString("uri", r.RequestURI)
+	enc.AddString("proto", r.Proto)
+	enc.AddString("remote_addr", r.RemoteAddr)
+	enc.AddString("host", r.Host)
+	enc.AddObject("headers", LoggableHTTPHeader(r.Header))
+	if r.TLS != nil {
+		enc.AddObject("tls", LoggableTLSConnState(*r.TLS))
+	}
+	return nil
+}
+
+// LoggableHTTPHeader makes an HTTP header loggable with zap.Object().
+type LoggableHTTPHeader http.Header
+
+// MarshalLogObject satisfies the zapcore.ObjectMarshaler interface.
+func (h LoggableHTTPHeader) MarshalLogObject(enc zapcore.ObjectEncoder) error {
+	if h == nil {
+		return nil
+	}
+	for key, val := range h {
+		enc.AddArray(key, LoggableStringArray(val))
+	}
+	return nil
+}
+
+// LoggableStringArray makes a slice of strings marshalable for logging.
+type LoggableStringArray []string
+
+// MarshalLogArray satisfies the zapcore.ArrayMarshaler interface.
+func (sa LoggableStringArray) MarshalLogArray(enc zapcore.ArrayEncoder) error {
+	if sa == nil {
+		return nil
+	}
+	for _, s := range sa {
+		enc.AppendString(s)
+	}
+	return nil
+}
+
+// LoggableTLSConnState makes a TLS connection state loggable with zap.Object().
+type LoggableTLSConnState tls.ConnectionState
+
+// MarshalLogObject satisfies the zapcore.ObjectMarshaler interface.
+func (t LoggableTLSConnState) MarshalLogObject(enc zapcore.ObjectEncoder) error {
+	enc.AddBool("resumed", t.DidResume)
+	enc.AddUint16("version", t.Version)
+	enc.AddUint16("resumed", t.CipherSuite)
+	enc.AddString("proto", t.NegotiatedProtocol)
+	enc.AddBool("proto_mutual", t.NegotiatedProtocolIsMutual)
+	enc.AddString("server_name", t.ServerName)
+	return nil
+}
+
+// Interface guards
+var (
+	_ zapcore.ObjectMarshaler = (*LoggableHTTPRequest)(nil)
+	_ zapcore.ObjectMarshaler = (*LoggableHTTPHeader)(nil)
+	_ zapcore.ArrayMarshaler  = (*LoggableStringArray)(nil)
+	_ zapcore.ObjectMarshaler = (*LoggableTLSConnState)(nil)
+)