Add Close method to logp.Logger (#205)

Add a close method to logp.Logger responsible for closing any
underlying core/output. All of our implementations of zapcore.Core
that use an output that can be closed now implement io.Closer.

This allows for closing any underlying files used by any output, which
can prevent issues on Windows.

It also removes a workaround for windows in a test because the log files
could not be closed.

Author: belimawr

NOTICE.txt

@@ -2055,6 +2055,72 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
+--------------------------------------------------------------------------------
+Dependency : golang.org/x/text
+Version: v0.14.0
+Licence type (autodetected): BSD-3-Clause
+--------------------------------------------------------------------------------
+
+Contents of probable licence file $GOMODCACHE/golang.org/x/[email protected]/LICENSE:
+
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+--------------------------------------------------------------------------------
+Dependency : gopkg.in/mcuadros/go-syslog.v2
+Version: v2.3.0
+Licence type (autodetected): MIT
+--------------------------------------------------------------------------------
+
+Contents of probable licence file $GOMODCACHE/gopkg.in/mcuadros/[email protected]/LICENSE:
+
+Copyright (c) 2013 Máximo Cuadros
+
+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.
+
+
 --------------------------------------------------------------------------------
 Dependency : gopkg.in/yaml.v2
 Version: v2.4.0
@@ -5038,43 +5104,6 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
---------------------------------------------------------------------------------
-Dependency : golang.org/x/text
-Version: v0.14.0
-Licence type (autodetected): BSD-3-Clause
---------------------------------------------------------------------------------
-
-Contents of probable licence file $GOMODCACHE/golang.org/x/[email protected]/LICENSE:
-
-Copyright (c) 2009 The Go Authors. All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are
-met:
-
-   * Redistributions of source code must retain the above copyright
-notice, this list of conditions and the following disclaimer.
-   * Redistributions in binary form must reproduce the above
-copyright notice, this list of conditions and the following disclaimer
-in the documentation and/or other materials provided with the
-distribution.
-   * Neither the name of Google Inc. nor the names of its
-contributors may be used to endorse or promote products derived from
-this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-
 --------------------------------------------------------------------------------
 Dependency : golang.org/x/tools
 Version: v0.6.0

go.mod

@@ -23,6 +23,8 @@ require (
 	golang.org/x/crypto v0.22.0
 	golang.org/x/net v0.23.0
 	golang.org/x/sys v0.19.0
+	golang.org/x/text v0.14.0
+	gopkg.in/mcuadros/go-syslog.v2 v2.3.0
 	gopkg.in/yaml.v2 v2.4.0
 )
 
@@ -51,7 +53,6 @@ require (
 	go.uber.org/multierr v1.11.0 // indirect
 	golang.org/x/mod v0.8.0 // indirect
 	golang.org/x/sync v0.6.0 // indirect
-	golang.org/x/text v0.14.0 // indirect
 	golang.org/x/tools v0.6.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	howett.net/plist v1.0.1 // indirect

go.sum

@@ -227,6 +227,8 @@ gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f h1:BLraFXnmrev5lT+xlilqcH8XK9/i0At2xKjWk4p6zsU=
 gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/hjson/hjson-go.v3 v3.0.1/go.mod h1:X6zrTSVeImfwfZLfgQdInl9mWjqPqgH90jom9nym/lw=
+gopkg.in/mcuadros/go-syslog.v2 v2.3.0 h1:kcsiS+WsTKyIEPABJBJtoG0KkOS6yzvJ+/eZlhD79kk=
+gopkg.in/mcuadros/go-syslog.v2 v2.3.0/go.mod h1:l5LPIyOOyIdQquNg+oU6Z3524YwrcqEm0aKH+5zpt2U=
 gopkg.in/yaml.v1 v1.0.0-20140924161607-9f9df34309c0/go.mod h1:WDnlLJ4WF5VGsH/HVa3CI79GS0ol3YnhVnKP89i0kNg=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

logp/core.go

@@ -63,6 +63,16 @@ type coreLogger struct {
 	observedLogs *observer.ObservedLogs // Contains events generated while in observation mode (a testing mode).
 }
 
+type closerCore struct {
+	zapcore.Core
+	io.Closer
+}
+
+func (c *closerCore) With(fields []zapcore.Field) zapcore.Core {
+	c.Core = c.Core.With(fields)
+	return c
+}
+
 // Configure configures the logp package.
 func Configure(cfg Config) error {
 	return ConfigureWithOutputs(cfg)
@@ -314,14 +324,35 @@ func makeFileOutput(cfg Config, enab zapcore.LevelEnabler) (zapcore.Core, error)
 		return nil, fmt.Errorf("failed to create file rotator: %w", err)
 	}
 
-	return newCore(buildEncoder(cfg), rotator, enab), nil
+	// Keep the same behaviour from before we introduced the closerCore.
+	core, err := newCore(buildEncoder(cfg), rotator, enab), nil
+	if err != nil {
+		return core, err
+	}
+
+	cc := closerCore{
+		Core:   core,
+		Closer: rotator,
+	}
+
+	return &cc, err
 }
 
 func newCore(enc zapcore.Encoder, ws zapcore.WriteSyncer, enab zapcore.LevelEnabler) zapcore.Core {
 	return wrappedCore(zapcore.NewCore(enc, ws, enab))
 }
 func wrappedCore(core zapcore.Core) zapcore.Core {
-	return ecszap.WrapCore(core)
+	wc := ecszap.WrapCore(core)
+
+	if closeCore, ok := core.(io.Closer); ok {
+		cc := closerCore{
+			Core:   wc,
+			Closer: closeCore,
+		}
+		return &cc
+	}
+
+	return wc
 }
 
 func globalLogger() *zap.Logger {
@@ -406,3 +437,17 @@ func (m multiCore) Sync() error {
 	}
 	return errors.Join(errs...)
 }
+
+// Close calls Close on any core that implements io.Closer.
+// All returned errors are joined by errors.Join and returned.
+func (m multiCore) Close() error {
+	errs := []error{}
+	for _, core := range m.cores {
+		if closer, ok := core.(io.Closer); ok {
+			closeErr := closer.Close()
+			errs = append(errs, closeErr)
+		}
+	}
+
+	return errors.Join(errs...)
+}

logp/core_linux_test.go

@@ -0,0 +1,80 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you 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.
+
+//go:build linux
+
+package logp
+
+import (
+	"io"
+	"testing"
+
+	"go.uber.org/zap/zapcore"
+	"gopkg.in/mcuadros/go-syslog.v2"
+)
+
+// TestSyslogOutputCanBeClosed instantiates a syslog output and ensures it
+// implements `io.Close`.
+//
+// We call close to ensure it does not return an error.
+//
+// Our syslog is hardcoded to connect via Unix sockets. The container
+// we use to run the tests does not have a syslog listening on Unix socket,
+// so we instantiate our own.
+func TestSyslogOutputCanBeClosed(t *testing.T) {
+	channel := make(syslog.LogPartsChannel)
+	handler := syslog.NewChannelHandler(channel)
+
+	server := syslog.NewServer()
+	server.SetFormat(syslog.RFC5424)
+	server.SetHandler(handler)
+
+	if err := server.ListenUnixgram("/var/run/syslog"); err != nil {
+		t.Errorf("cannot configure syslog to listen on '/var/run/syslog/': %s", err)
+		t.Log("You might already have a syslog running, this test assumes " +
+			"there is no syslog running on the host. You can run this test " +
+			"in a Docker container (adjust the image tag to the current " +
+			"Go version):\n" +
+			"'docker run --rm -it -v $PWD:$PWD -w $PWD golang:1.21.10 go test ./logp'")
+	}
+
+	if err := server.Boot(); err != nil {
+		t.Fatalf("cannot start syslog server: %s", err)
+	}
+
+	t.Cleanup(func() {
+		// ignore the error, we just need it to accept
+		// connections from our syslog output
+		_ = server.Kill()
+	})
+
+	cfg := DefaultConfig(DefaultEnvironment)
+	cfg.ToFiles = true
+
+	syslogOutput, err := makeSyslogOutput(cfg, zapcore.DebugLevel)
+	if err != nil {
+		t.Fatalf("cannot create syslog output: %s", err)
+	}
+
+	closer, ok := syslogOutput.(io.Closer)
+	if !ok {
+		t.Fatal("the 'Syslog Output' does not implement io.Closer")
+	}
+	if err := closer.Close(); err != nil {
+		t.Fatalf("Close must not return any error, got: %s", err)
+	}
+}

logp/core_test.go

@@ -25,7 +25,6 @@ import (
 	golog "log"
 	"os"
 	"path/filepath"
-	"runtime"
 	"strings"
 	"testing"
 
@@ -222,33 +221,10 @@ func TestLoggingECSFields(t *testing.T) {
 }
 
 func TestCreatingNewLoggerWithDifferentOutput(t *testing.T) {
-	var tempDir1, tempDir2 string
-	// Because of the way logp and zap work, when the test finishes, the log
-	// file is still open, this creates a problem on Windows because the
-	// temporary directory cannot be removed if a file inside it is still
-	// open.
-	// See https://github.com/elastic/elastic-agent-libs/issues/179
-	// for more details
-	//
-	// To circumvent this problem on Windows we use os.MkdirTemp
-	// leaving it behind and delegating to the OS the responsibility
-	// of cleaning it up (usually on restart).
-	if runtime.GOOS == "windows" {
-		var err error
-		tempDir1, err = os.MkdirTemp("", t.Name()+"-*")
-		if err != nil {
-			t.Fatalf("could not create temporary directory: %s", err)
-		}
-		tempDir2, err = os.MkdirTemp("", t.Name()+"-*")
-		if err != nil {
-			t.Fatalf("could not create temporary directory: %s", err)
-		}
-	} else {
-		// We have no problems on Linux and Darwin, so we can rely on t.TempDir
-		// that will remove the files once the tests finishes.
-		tempDir1 = t.TempDir()
-		tempDir2 = t.TempDir()
-	}
+	// We have no problems on Linux and Darwin, so we can rely on t.TempDir
+	// that will remove the files once the tests finishes.
+	tempDir1 := t.TempDir()
+	tempDir2 := t.TempDir()
 
 	secondLoggerMessage := "this is a log message"
 	secondLoggerName := t.Name() + "-second"
@@ -279,6 +255,11 @@ func TestCreatingNewLoggerWithDifferentOutput(t *testing.T) {
 	if err := logger.Sync(); err != nil {
 		t.Fatalf("could not sync log file from fist logger: %s", err)
 	}
+	t.Cleanup(func() {
+		if err := logger.Close(); err != nil {
+			t.Fatalf("could not close first logger: %s", err)
+		}
+	})
 
 	// Actually clones the logger and use the "WithFileOutput" function
 	secondCfg := DefaultConfig(DefaultEnvironment)
@@ -303,6 +284,11 @@ func TestCreatingNewLoggerWithDifferentOutput(t *testing.T) {
 	if err := secondLogger.Sync(); err != nil {
 		t.Fatalf("could not sync log file from second logger: %s", err)
 	}
+	t.Cleanup(func() {
+		if err := secondLogger.Close(); err != nil {
+			t.Fatalf("could not close second logger: %s", err)
+		}
+	})
 
 	// Write again with the first logger to ensure it has not been affected
 	// by the new configuration on the second logger.
@@ -631,6 +617,24 @@ func TestCreateLogOutputAllDisabled(t *testing.T) {
 	}
 }
 
+func TestCoresCanBeClosed(t *testing.T) {
+	cfg := DefaultConfig(DefaultEnvironment)
+	cfg.ToFiles = true
+
+	fileOutput, err := makeFileOutput(cfg, zapcore.DebugLevel)
+	if err != nil {
+		t.Fatalf("cannot create file output: %s", err)
+	}
+
+	closer, ok := fileOutput.(io.Closer)
+	if !ok {
+		t.Fatal("the 'File Output' does not implement io.Closer")
+	}
+	if err := closer.Close(); err != nil {
+		t.Fatalf("Close must not return any error, got: %s", err)
+	}
+}
+
 func strField(key, val string) zapcore.Field {
 	return zapcore.Field{Type: zapcore.StringType, Key: key, String: val}
 }