logging: Implement net writer (#2884)

* Implement UDP writer

* Implement Net Writer

* Utilize Caddy's address parsing functions

* A couple little fixes (see #2884)

admin.go

@@ -711,6 +711,12 @@ traverseLoop:
 					return fmt.Errorf("unrecognized method %s", method)
 				}
 			} else {
+				// if we are "PUTting" a new resource, the key(s) in its path
+				// might not exist yet; that's OK but we need to make them as
+				// we go, while we still have a pointer from the level above
+				if v[part] == nil && method == http.MethodPut {
+					v[part] = make(map[string]interface{})
+				}
 				ptr = v[part]
 			}
 

caddy.go

@@ -134,7 +134,7 @@ func changeConfig(method, path string, input []byte, forceReload bool) error {
 
 	// if nothing changed, no need to do a whole reload unless the client forces it
 	if !forceReload && bytes.Equal(rawCfgJSON, newCfg) {
-		Log().Named("admin.api.change_config").Info("config is unchanged")
+		Log().Named("admin.api").Info("config is unchanged")
 		return nil
 	}
 

logging.go

@@ -225,10 +225,11 @@ func (logging *Logging) openWriter(opener WriterOpener) (io.WriteCloser, bool, e
 		w, err := opener.OpenWriter()
 		return writerDestructor{w}, err
 	})
-	if err == nil {
+	if err != nil {
-		logging.writerKeys = append(logging.writerKeys, key)
+		return nil, false, err
 	}
-	return writer.(io.WriteCloser), !loaded, err
+	logging.writerKeys = append(logging.writerKeys, key)
+	return writer.(io.WriteCloser), !loaded, nil
 }
 
 // WriterOpener is a module that can open a log writer.

modules/logging/netwriter.go

@@ -0,0 +1,82 @@
+// 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 logging
+
+import (
+	"fmt"
+	"io"
+	"net"
+
+	"github.com/caddyserver/caddy/v2"
+)
+
+func init() {
+	caddy.RegisterModule(NetWriter{})
+}
+
+// NetWriter implements a log writer that outputs to a network socket.
+type NetWriter struct {
+	Address string `json:"address,omitempty"`
+
+	addr caddy.ParsedAddress
+}
+
+// CaddyModule returns the Caddy module information.
+func (NetWriter) CaddyModule() caddy.ModuleInfo {
+	return caddy.ModuleInfo{
+		ID:  "caddy.logging.writers.net",
+		New: func() caddy.Module { return new(NetWriter) },
+	}
+}
+
+// Provision sets up the module.
+func (nw *NetWriter) Provision(ctx caddy.Context) error {
+	repl := caddy.NewReplacer()
+	address, err := repl.ReplaceOrErr(nw.Address, true, true)
+	if err != nil {
+		return fmt.Errorf("invalid host in address: %v", err)
+	}
+
+	nw.addr, err = caddy.ParseNetworkAddress(address)
+	if err != nil {
+		return fmt.Errorf("parsing network address '%s': %v", address, err)
+	}
+
+	if nw.addr.PortRangeSize() != 1 {
+		return fmt.Errorf("multiple ports not supported")
+	}
+
+	return nil
+}
+
+func (nw NetWriter) String() string {
+	return nw.addr.String()
+}
+
+// WriterKey returns a unique key representing this nw.
+func (nw NetWriter) WriterKey() string {
+	return nw.addr.String()
+}
+
+// OpenWriter opens a new network connection.
+func (nw NetWriter) OpenWriter() (io.WriteCloser, error) {
+	return net.Dial(nw.addr.Network, nw.addr.JoinHostPort(0))
+}
+
+// Interface guards
+var (
+	_ caddy.Provisioner  = (*NetWriter)(nil)
+	_ caddy.WriterOpener = (*NetWriter)(nil)
+)