add an in-memory logger and use it on install and uninstall (#4485)

internal/pkg/agent/cmd/install.go

@@ -193,28 +193,13 @@ func installCmd(streams *cli.IOStreams, cmd *cobra.Command) error {
 
 	progBar := install.CreateAndStartNewSpinner(streams.Out, "Installing Elastic Agent...")
 
-	logCfg := logp.DefaultConfig(logp.DefaultEnvironment)
-	logCfg.Level = logp.DebugLevel
-	// Using in memory logger, so we don't write logs to the
-	// directory we are trying to delete
-	logp.ToObserverOutput()(&logCfg)
-
-	err = logp.Configure(logCfg)
-	if err != nil {
-		return fmt.Errorf("error creating logging config: %w", err)
-	}
-
-	log := logger.NewWithoutConfig("")
-
+	log, logBuff := logger.NewInMemory("install", logp.ConsoleEncoderConfig())
 	defer func() {
 		if err == nil {
 			return
 		}
-		oLogs := logp.ObserverLogs().TakeAll()
 		fmt.Fprintf(os.Stderr, "Error uninstalling. Printing logs\n")
-		for _, oLog := range oLogs {
-			fmt.Fprintf(os.Stderr, "%v\n", oLog.Entry)
-		}
+		fmt.Fprint(os.Stderr, logBuff.String())
 	}()
 
 	var ownership utils.FileOwner

internal/pkg/agent/cmd/uninstall.go

@@ -11,7 +11,6 @@ import (
 	"github.com/spf13/cobra"
 
 	"github.com/elastic/elastic-agent-libs/logp"
-
 	"github.com/elastic/elastic-agent/internal/pkg/agent/application/paths"
 	"github.com/elastic/elastic-agent/internal/pkg/agent/install"
 	"github.com/elastic/elastic-agent/internal/pkg/cli"
@@ -86,28 +85,13 @@ func uninstallCmd(streams *cli.IOStreams, cmd *cobra.Command) error {
 
 	progBar := install.CreateAndStartNewSpinner(streams.Out, "Uninstalling Elastic Agent...")
 
-	logCfg := logp.DefaultConfig(logp.DefaultEnvironment)
-	logCfg.Level = logp.DebugLevel
-	// Using in memory logger, so we don't write logs to the
-	// directory we are trying to delete
-	logp.ToObserverOutput()(&logCfg)
-
-	err = logp.Configure(logCfg)
-	if err != nil {
-		return fmt.Errorf("error creating logging config: %w", err)
-	}
-
-	log := logger.NewWithoutConfig("")
-
+	log, logBuff := logger.NewInMemory("uninstall", logp.ConsoleEncoderConfig())
 	defer func() {
 		if err == nil {
 			return
 		}
-		oLogs := logp.ObserverLogs().TakeAll()
 		fmt.Fprintf(os.Stderr, "Error uninstalling. Printing logs\n")
-		for _, oLog := range oLogs {
-			fmt.Fprintf(os.Stderr, "%v\n", oLog.Entry)
-		}
+		fmt.Fprint(os.Stderr, logBuff.String())
 	}()
 
 	err = install.Uninstall(paths.ConfigFile(), paths.Top(), uninstallToken, log, progBar)

pkg/core/logger/logger.go

@@ -5,6 +5,7 @@
 package logger
 
 import (
+	"bytes"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -72,6 +73,31 @@ func NewWithoutConfig(name string) *Logger {
 	return logp.NewLogger(name)
 }
 
+// NewInMemory returns a new in-memory logger along with the buffer to which i
+// logs.
+// encCfg configures the log format, use logp.ConsoleEncoderConfig for console
+// format, logp.JSONEncoderConfig for JSON or any other valid zapcore.EncoderConfig.
+func NewInMemory(selector string, encCfg zapcore.EncoderConfig) (*Logger, *bytes.Buffer) {
+	buff := bytes.Buffer{}
+
+	encoderConfig := ecszap.ECSCompatibleEncoderConfig(encCfg)
+	encoderConfig.EncodeTime = UtcTimestampEncode
+	encoder := zapcore.NewConsoleEncoder(encoderConfig)
+
+	core := zapcore.NewCore(
+		encoder,
+		zapcore.AddSync(&buff),
+		zap.NewAtomicLevelAt(zap.DebugLevel))
+	ecszap.ECSCompatibleEncoderConfig(logp.ConsoleEncoderConfig())
+
+	logger := logp.NewLogger(
+		selector,
+		zap.WrapCore(func(in zapcore.Core) zapcore.Core {
+			return core
+		}))
+	return logger, &buff
+}
+
 // AddCallerSkip returns new logger with incremented stack frames to skip.
 // This is needed in order to correctly report the log file lines when the logging statement
 // is wrapped in some convenience wrapping function for example.
@@ -147,7 +173,7 @@ func DefaultLoggingConfig() *Config {
 	return &cfg
 }
 
-// makeInternalFileOutput creates a zapcore.Core logger that cannot be changed with configuration.
+// MakeInternalFileOutput creates a zapcore.Core logger that cannot be changed with configuration.
 //
 // This is the logger that the spawned filebeat expects to read the log file from and ship to ES.
 func MakeInternalFileOutput(cfg *Config) (zapcore.Core, error) {

pkg/core/logger/logger_test.go

@@ -5,8 +5,10 @@
 package logger
 
 import (
+	"strings"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.uber.org/zap/zapcore"
 
@@ -56,3 +58,31 @@ func Test_SetLevel(t *testing.T) {
 		require.Equal(t, tc.ErrEnabled, internalLevelEnabler.Enabled(zapcore.ErrorLevel))
 	}
 }
+
+func TestNewInMemory(t *testing.T) {
+	log, buff := NewInMemory("in_memory", logp.ConsoleEncoderConfig())
+
+	log.Debugw("a debug message", "debug_key", "debug_val")
+	log.Infow("a info message", "info_key", "info_val")
+	log.Warnw("a warn message", "warn_key", "warn_val")
+	log.Errorw("an error message", "error_key", "error_val")
+
+	logs := strings.Split(strings.TrimSpace(buff.String()), "\n")
+	assert.Len(t, logs, 4, "expected 4 log entries")
+
+	assert.Contains(t, logs[0], "a debug message")
+	assert.Contains(t, logs[0], "debug_key")
+	assert.Contains(t, logs[0], "debug_val")
+
+	assert.Contains(t, logs[1], "a info message")
+	assert.Contains(t, logs[1], "info_key")
+	assert.Contains(t, logs[1], "info_val")
+
+	assert.Contains(t, logs[2], "a warn message")
+	assert.Contains(t, logs[2], "warn_key")
+	assert.Contains(t, logs[2], "warn_val")
+
+	assert.Contains(t, logs[3], "an error message")
+	assert.Contains(t, logs[3], "error_key")
+	assert.Contains(t, logs[3], "error_val")
+}