refactor: allow callers to directly set logfile location (#2545)

Changes `message.UseLogFile` to accept an `f *os.File` and wrap it in a
`*message.PausableWriter`. Adds unit tests for `PausableWriter`.

## Related Issue

Fixes #2524 

## Checklist before merging

- [x] Test, docs, adr added or updated as needed
- [x] [Contributor Guide
Steps](https://github.com/defenseunicorns/zarf/blob/main/.github/CONTRIBUTING.md#developer-workflow)
followed

---------

Signed-off-by: razzle <harry@razzle.cloud>

src/cmd/common/setup.go

@@ -5,8 +5,10 @@
 package common
 
 import (
+	"fmt"
 	"io"
 	"os"
+	"time"
 
 	"github.com/defenseunicorns/zarf/src/config"
 	"github.com/defenseunicorns/zarf/src/config/lang"
@@ -51,14 +53,20 @@ func SetupCLI() {
 	}
 
 	if !config.SkipLogFile {
-		logFile, err := message.UseLogFile("")
+		ts := time.Now().Format("2006-01-02-15-04-05")
+
+		f, err := os.CreateTemp("", fmt.Sprintf("zarf-%s-*.log", ts))
+		if err != nil {
+			message.WarnErr(err, "Error creating a log file in a temporary directory")
+			return
+		}
+		logFile, err := message.UseLogFile(f)
 		if err != nil {
 			message.WarnErr(err, "Error saving a log file to a temporary directory")
 			return
 		}
 
 		pterm.SetDefaultOutput(io.MultiWriter(os.Stderr, logFile))
-		location := message.LogFileLocation()
-		message.Notef("Saving log file to %s", location)
+		message.Notef("Saving log file to %s", f.Name())
 	}
 }

src/pkg/message/credentials.go

@@ -32,8 +32,8 @@ func PrintCredentialTable(state *types.ZarfState, componentsToDeploy []types.Dep
 
 	// Pause the logfile's output to avoid credentials being printed to the log file
 	if logFile != nil {
-		logFile.pause()
-		defer logFile.resume()
+		logFile.Pause()
+		defer logFile.Resume()
 	}
 
 	loginData := [][]string{}
@@ -95,8 +95,8 @@ func PrintComponentCredential(state *types.ZarfState, componentName string) {
 func PrintCredentialUpdates(oldState *types.ZarfState, newState *types.ZarfState, services []string) {
 	// Pause the logfile's output to avoid credentials being printed to the log file
 	if logFile != nil {
-		logFile.pause()
-		defer logFile.resume()
+		logFile.Pause()
+		defer logFile.Resume()
 	}
 
 	for _, service := range services {

src/pkg/message/message.go

@@ -7,7 +7,6 @@ package message
 import (
 	"encoding/json"
 	"fmt"
-	"io"
 	"net/http"
 	"os"
 	"runtime/debug"
@@ -49,7 +48,7 @@ var RuleLine = strings.Repeat("━", TermWidth)
 var logLevel = InfoLevel
 
 // logFile acts as a buffer for logFile generation
-var logFile *pausableLogFile
+var logFile *PausableWriter
 
 // DebugWriter represents a writer interface that writes to message.Debug
 type DebugWriter struct{}
@@ -77,32 +76,14 @@ func init() {
 	pterm.SetDefaultOutput(os.Stderr)
 }
 
-// UseLogFile writes output to stderr and a logFile.
-func UseLogFile(dir string) (io.Writer, error) {
-	// Prepend the log filename with a timestamp.
-	ts := time.Now().Format("2006-01-02-15-04-05")
-
-	f, err := os.CreateTemp(dir, fmt.Sprintf("zarf-%s-*.log", ts))
-	if err != nil {
-		return nil, err
-	}
-
-	logFile = &pausableLogFile{
-		wr: f,
-		f:  f,
-	}
+// UseLogFile wraps a given file in a PausableWriter
+// and sets it as the log file used by the message package.
+func UseLogFile(f *os.File) (*PausableWriter, error) {
+	logFile = NewPausableWriter(f)
 
 	return logFile, nil
 }
 
-// LogFileLocation returns the location of the log file.
-func LogFileLocation() string {
-	if logFile == nil {
-		return ""
-	}
-	return logFile.f.Name()
-}
-
 // SetLogLevel sets the log level.
 func SetLogLevel(lvl LogLevel) {
 	logLevel = lvl

src/pkg/message/pausable.go

@@ -6,26 +6,29 @@ package message
 
 import (
 	"io"
-	"os"
 )
 
-// pausableLogFile is a pausable log file
-type pausableLogFile struct {
-	wr io.Writer
-	f  *os.File
+// PausableWriter is a pausable writer
+type PausableWriter struct {
+	out, wr io.Writer
 }
 
-// pause the log file
-func (l *pausableLogFile) pause() {
-	l.wr = io.Discard
+// NewPausableWriter creates a new pausable writer
+func NewPausableWriter(wr io.Writer) *PausableWriter {
+	return &PausableWriter{out: wr, wr: wr}
 }
 
-// resume the log file
-func (l *pausableLogFile) resume() {
-	l.wr = l.f
+// Pause sets the output writer to io.Discard
+func (pw *PausableWriter) Pause() {
+	pw.out = io.Discard
 }
 
-// Write writes the data to the log file
-func (l *pausableLogFile) Write(p []byte) (n int, err error) {
-	return l.wr.Write(p)
+// Resume sets the output writer back to the original writer
+func (pw *PausableWriter) Resume() {
+	pw.out = pw.wr
+}
+
+// Write writes the data to the underlying output writer
+func (pw *PausableWriter) Write(p []byte) (n int, err error) {
+	return pw.out.Write(p)
 }

src/pkg/message/pausable_test.go

@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2021-Present The Zarf Authors
+
+package message
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPausableWriter(t *testing.T) {
+	var buf bytes.Buffer
+
+	pw := NewPausableWriter(&buf)
+
+	n, err := pw.Write([]byte("foo"))
+	require.NoError(t, err)
+	require.Equal(t, 3, n)
+
+	require.Equal(t, "foo", buf.String())
+
+	pw.Pause()
+
+	n, err = pw.Write([]byte("bar"))
+	require.NoError(t, err)
+	require.Equal(t, 3, n)
+
+	require.Equal(t, "foo", buf.String())
+
+	pw.Resume()
+
+	n, err = pw.Write([]byte("baz"))
+	require.NoError(t, err)
+	require.Equal(t, 3, n)
+
+	require.Equal(t, "foobaz", buf.String())
+}