Add rusage-logfile flag to optionally send rusage to a file

Currently the rusage is reported to stdout and rather cumbersome to parse. The
new flag rusage-logfile can be used to specify a file to which the log will be
written instead.

Signed-off-by: Dan Čermák <dcermak@suse.com>

cmd/buildah/bud.go

@@ -334,6 +334,7 @@ func budCmd(c *cobra.Command, inputArgs []string, iopts budOptions) error {
 		Isolation:               isolation,
 		Labels:                  iopts.Label,
 		Layers:                  layers,
+		LogRusage:               iopts.LogRusage,
 		Manifest:                iopts.Manifest,
 		MaxPullPushRetries:      maxPullPushRetries,
 		NamespaceOptions:        namespaceOptions,
@@ -349,6 +350,7 @@ func budCmd(c *cobra.Command, inputArgs []string, iopts budOptions) error {
 		ReportWriter:            reporter,
 		Runtime:                 iopts.Runtime,
 		RuntimeArgs:             runtimeFlags,
+		RusageLogFile:           iopts.RusageLogFile,
 		SignBy:                  iopts.SignBy,
 		SignaturePolicyPath:     iopts.SignaturePolicy,
 		Squash:                  iopts.Squash,
@@ -357,7 +359,6 @@ func budCmd(c *cobra.Command, inputArgs []string, iopts budOptions) error {
 		TransientMounts:         iopts.Volumes,
 		OciDecryptConfig:        decConfig,
 		Jobs:                    &iopts.Jobs,
-		LogRusage:               iopts.LogRusage,
 	}
 	if iopts.IgnoreFile != "" {
 		excludes, err := parseDockerignore(iopts.IgnoreFile)

define/build.go

@@ -217,6 +217,8 @@ type BuildOptions struct {
 	Jobs *int
 	// LogRusage logs resource usage for each step.
 	LogRusage bool
+	// File to which the Rusage logs will be saved to instead of stdout
+	RusageLogFile string
 	// Excludes is a list of excludes to be used instead of the .dockerignore file.
 	Excludes []string
 	// From is the image name to use to replace the value specified in the first

imagebuildah/executor.go

@@ -116,6 +116,7 @@ type Executor struct {
 	stagesSemaphore                *semaphore.Weighted
 	jobs                           int
 	logRusage                      bool
+	rusageLogFile                  *os.File
 	imageInfoLock                  sync.Mutex
 	imageInfoCache                 map[string]imageTypeAndHistoryAndDiffIDs
 	fromOverride                   string
@@ -183,6 +184,18 @@ func NewExecutor(logger *logrus.Logger, store storage.Store, options define.Buil
 		writer = ioutil.Discard
 	}
 
+	var rusageLogFile *os.File
+	if options.LogRusage && !options.Quiet {
+		if options.RusageLogFile == "" {
+			rusageLogFile = os.Stdout
+		} else {
+			rusageLogFile, err = os.OpenFile(options.RusageLogFile, os.O_TRUNC|os.O_CREATE|os.O_WRONLY, 0644)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
 	exec := Executor{
 		logger:                         logger,
 		stages:                         make(map[string]*StageExecutor),
@@ -241,6 +254,7 @@ func NewExecutor(logger *logrus.Logger, store storage.Store, options define.Buil
 		terminatedStage:                make(map[string]struct{}),
 		jobs:                           jobs,
 		logRusage:                      options.LogRusage,
+		rusageLogFile:                  rusageLogFile,
 		imageInfoCache:                 make(map[string]imageTypeAndHistoryAndDiffIDs),
 		fromOverride:                   options.From,
 		manifest:                       options.Manifest,
@@ -530,6 +544,12 @@ func (b *Executor) Build(ctx context.Context, stages imagebuilder.Stages) (image
 			}
 		}
 		cleanupImages = nil
+
+		if b.rusageLogFile != nil && b.rusageLogFile != os.Stdout {
+			// we deliberately ignore the error here, as this
+			// function can be called multiple times
+			b.rusageLogFile.Close()
+		}
 		return lastErr
 	}
 

imagebuildah/stage_executor.go

@@ -704,8 +704,8 @@ func (s *StageExecutor) Execute(ctx context.Context, base string) (imgID string,
 				fmt.Fprintf(s.executor.out, "error gathering resource usage information: %v\n", err)
 				return
 			}
-			if !s.executor.quiet && s.executor.logRusage {
-				fmt.Fprintf(s.executor.out, "%s\n", rusage.FormatDiff(usage.Subtract(resourceUsage)))
+			if s.executor.rusageLogFile != nil {
+				fmt.Fprintf(s.executor.rusageLogFile, "%s\n", rusage.FormatDiff(usage.Subtract(resourceUsage)))
 			}
 			resourceUsage = usage
 		}

pkg/cli/common.go

@@ -84,6 +84,7 @@ type BudResults struct {
 	TLSVerify           bool
 	Jobs                int
 	LogRusage           bool
+	RusageLogFile       string
 }
 
 // FromAndBugResults represents the results for common flags
@@ -199,6 +200,10 @@ func GetBudFlags(flags *BudResults) pflag.FlagSet {
 	if err := fs.MarkHidden("log-rusage"); err != nil {
 		panic(fmt.Sprintf("error marking the log-rusage flag as hidden: %v", err))
 	}
+	fs.StringVar(&flags.RusageLogFile, "rusage-logfile", "", "destination file to which rusage should be logged to instead of stdout (= the default).")
+	if err := fs.MarkHidden("rusage-logfile"); err != nil {
+		panic(fmt.Sprintf("error marking the rusage-logfile flag as hidden: %v", err))
+	}
 	fs.StringVar(&flags.Manifest, "manifest", "", "add the image to the specified manifest list. Creates manifest if it does not exist")
 	fs.BoolVar(&flags.NoCache, "no-cache", false, "Do not use existing cached images for the container build. Build from the start with a new set of cached layers.")
 	fs.String("os", runtime.GOOS, "set the OS to the provided value instead of the current operating system of the host")

tests/bud.bats

@@ -2423,6 +2423,19 @@ EOM
   expect_output --substring ".*\(system\).*\(user\).*\(elapsed\).*input.*output"
 }
 
+@test "bud with-rusage-logfile" {
+  _prefetch alpine
+  run_buildah bud --log-rusage --rusage-logfile "foo.log" --layers --pull=false --format docker --signature-policy ${TESTSDIR}/policy.json ${TESTSDIR}/bud/shell
+  # the logfile should exist
+  if [ ! -e "foo.log" ]; then die "foo.log not present!"; fi
+  # expect that foo.log only contains lines that were formatted using pkg/rusage.FormatDiff()
+  formatted_lines=$(grep ".*\(system\).*\(user\).*\(elapsed\).*input.*output" foo.log | wc -l)
+  line_count=$(cat foo.log | wc -l)
+  if [[ "$formatted_lines" -ne "$line_count" ]]; then
+      die "Got ${formatted_lines} lines formatted with pkg/rusage.FormatDiff() but foo.log has ${line_count} lines"
+  fi
+}
+
 @test "bud-caching-from-scratch" {
   _prefetch alpine
   # run the build once