feat: Catch panic to generate report and reraise

build/panic_reporter.go

@@ -0,0 +1,183 @@
+package build
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"runtime/debug"
+	"runtime/pprof"
+	"strconv"
+	"syscall"
+	"time"
+
+	"github.com/icza/backscanner"
+	logging "github.com/ipfs/go-log/v2"
+)
+
+var (
+	panicLog           = logging.Logger("panic-reporter")
+	defaultJournalTail = 500
+)
+
+// PanicReportingPath is the name of the subdir created within the repoPath
+// path provided to GeneratePanicReport
+var PanicReportingPath = "panic-reports"
+
+// PanicReportJournalTail is the number of lines captured from the end of
+// the lotus journal to be included in the panic report.
+var PanicReportJournalTail = defaultJournalTail
+
+// GeneratePanicReport produces a timestamped dump of the application state
+// for inspection and debugging purposes. Call this function from any place
+// where a panic or severe error needs to be examined. `persistPath` is the
+// path where the reports should be saved. `repoPath` is the path where the
+// journal should be read from. `label` is an optional string to include
+// next to the report timestamp.
+func GeneratePanicReport(persistPath, repoPath, label string) {
+	// make sure we always dump the latest logs on the way out
+	// especially since we're probably panicking
+	defer panicLog.Sync() //nolint:errcheck
+
+	if persistPath == "" && repoPath == "" {
+		panicLog.Warn("missing persist and repo paths, aborting panic report creation")
+		return
+	}
+
+	reportPath := filepath.Join(repoPath, PanicReportingPath, generateReportName(label))
+	if persistPath != "" {
+		reportPath = filepath.Join(persistPath, generateReportName(label))
+	}
+	panicLog.Warnf("generating panic report at %s", reportPath)
+
+	tl := os.Getenv("LOTUS_PANIC_JOURNAL_LOOKBACK")
+	if tl != "" && PanicReportJournalTail == defaultJournalTail {
+		i, err := strconv.Atoi(tl)
+		if err == nil {
+			PanicReportJournalTail = i
+		}
+	}
+
+	syscall.Umask(0)
+	err := os.MkdirAll(reportPath, 0755)
+	if err != nil {
+		panicLog.Error(err.Error())
+		return
+	}
+
+	writeAppVersion(filepath.Join(reportPath, "version"))
+	writeStackTrace(filepath.Join(reportPath, "stacktrace.dump"))
+	writeProfile("goroutines", filepath.Join(reportPath, "goroutines.pprof.gz"))
+	writeProfile("heap", filepath.Join(reportPath, "heap.pprof.gz"))
+	writeJournalTail(PanicReportJournalTail, repoPath, filepath.Join(reportPath, "journal.ndjson"))
+}
+
+func writeAppVersion(file string) {
+	f, err := os.Create(file)
+	if err != nil {
+		panicLog.Error(err.Error())
+	}
+	defer f.Close() //nolint:errcheck
+
+	versionString := []byte(BuildVersion + BuildTypeString() + CurrentCommit + "\n")
+	if _, err := f.Write(versionString); err != nil {
+		panicLog.Error(err.Error())
+	}
+}
+
+func writeStackTrace(file string) {
+	f, err := os.Create(file)
+	if err != nil {
+		panicLog.Error(err.Error())
+	}
+	defer f.Close() //nolint:errcheck
+
+	if _, err := f.Write(debug.Stack()); err != nil {
+		panicLog.Error(err.Error())
+	}
+
+}
+
+func writeProfile(profileType string, file string) {
+	p := pprof.Lookup(profileType)
+	if p == nil {
+		panicLog.Warnf("%s profile not available", profileType)
+		return
+	}
+	f, err := os.Create(file)
+	if err != nil {
+		panicLog.Error(err.Error())
+		return
+	}
+	defer f.Close() //nolint:errcheck
+
+	if err := p.WriteTo(f, 0); err != nil {
+		panicLog.Error(err.Error())
+	}
+}
+
+func writeJournalTail(tailLen int, repoPath, file string) {
+	if repoPath == "" {
+		panicLog.Warn("repo path is empty, aborting copy of journal log")
+		return
+	}
+
+	f, err := os.Create(file)
+	if err != nil {
+		panicLog.Error(err.Error())
+		return
+	}
+	defer f.Close() //nolint:errcheck
+
+	jPath, err := getLatestJournalFilePath(repoPath)
+	if err != nil {
+		panicLog.Warnf("failed getting latest journal: %s", err.Error())
+		return
+	}
+	j, err := os.OpenFile(jPath, os.O_RDONLY, 0400)
+	if err != nil {
+		panicLog.Error(err.Error())
+		return
+	}
+	js, err := j.Stat()
+	if err != nil {
+		panicLog.Error(err.Error())
+		return
+	}
+	jScan := backscanner.New(j, int(js.Size()))
+	linesWritten := 0
+	for {
+		if linesWritten > tailLen {
+			break
+		}
+		line, _, err := jScan.LineBytes()
+		if err != nil {
+			if err != io.EOF {
+				panicLog.Error(err.Error())
+			}
+			break
+		}
+		if _, err := f.Write(line); err != nil {
+			panicLog.Error(err.Error())
+			break
+		}
+		if _, err := f.Write([]byte("\n")); err != nil {
+			panicLog.Error(err.Error())
+			break
+		}
+		linesWritten++
+	}
+}
+
+func getLatestJournalFilePath(repoPath string) (string, error) {
+	journalPath := filepath.Join(repoPath, "journal")
+	entries, err := os.ReadDir(journalPath)
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(journalPath, entries[len(entries)-1].Name()), nil
+}
+
+func generateReportName(label string) string {
+	return fmt.Sprintf("report_%s_%s", label, time.Now().Format("2006-01-02T150405Z0700"))
+}

build/version.go

@@ -16,7 +16,7 @@ const (
 	BuildButterflynet = 0x7
 )
 
-func buildType() string {
+func BuildTypeString() string {
 	switch BuildType {
 	case BuildDefault:
 		return ""
@@ -47,5 +47,5 @@ func UserVersion() string {
 		return BuildVersion
 	}
 
-	return BuildVersion + buildType() + CurrentCommit
+	return BuildVersion + BuildTypeString() + CurrentCommit
 }

cmd/lotus-miner/main.go

@@ -113,6 +113,12 @@ func main() {
 				Usage:       "use color in display output",
 				DefaultText: "depends on output being a TTY",
 			},
+			&cli.StringFlag{
+				Name:    "panic-reports",
+				EnvVars: []string{"LOTUS_PANIC_REPORT_PATH"},
+				Hidden:  true,
+				Value:   "~/.lotus", // should follow --repo default
+			},
 			&cli.StringFlag{
 				Name:    "repo",
 				EnvVars: []string{"LOTUS_PATH"},
@@ -146,6 +152,14 @@ func main() {
 			}
 			return nil
 		},
+		After: func(c *cli.Context) error {
+			if r := recover(); r != nil {
+				// Generate report in LOTUS_PATH and re-raise panic
+				build.GeneratePanicReport(c.String("panic-reports"), c.String("repo"), c.App.Name)
+				panic(r)
+			}
+			return nil
+		},
 	}
 	app.Setup()
 	app.Metadata["repoType"] = repo.StorageMiner

cmd/lotus-seal-worker/main.go

@@ -75,6 +75,12 @@ func main() {
 				Value:   "~/.lotusworker", // TODO: Consider XDG_DATA_HOME
 				Usage:   fmt.Sprintf("Specify worker repo path. flag %s and env WORKER_PATH are DEPRECATION, will REMOVE SOON", FlagWorkerRepoDeprecation),
 			},
+			&cli.StringFlag{
+				Name:    "panic-reports",
+				EnvVars: []string{"LOTUS_PANIC_REPORT_PATH"},
+				Hidden:  true,
+				Value:   "~/.lotus", // should follow --repo default
+			},
 			&cli.StringFlag{
 				Name:    "miner-repo",
 				Aliases: []string{"storagerepo"},
@@ -89,6 +95,14 @@ func main() {
 			},
 		},
 
+		After: func(c *cli.Context) error {
+			if r := recover(); r != nil {
+				// Generate report in LOTUS_PATH and re-raise panic
+				build.GeneratePanicReport(c.String("panic-reports"), c.String(FlagWorkerRepo), c.App.Name)
+				panic(r)
+			}
+			return nil
+		},
 		Commands: local,
 	}
 	app.Setup()

cmd/lotus/main.go

@@ -67,6 +67,12 @@ func main() {
 		Version:              build.UserVersion(),
 		EnableBashCompletion: true,
 		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:    "panic-reports",
+				EnvVars: []string{"LOTUS_PANIC_REPORT_PATH"},
+				Hidden:  true,
+				Value:   "~/.lotus", // should follow --repo default
+			},
 			&cli.StringFlag{
 				Name:    "repo",
 				EnvVars: []string{"LOTUS_PATH"},
@@ -84,6 +90,14 @@ func main() {
 			},
 			cliutil.FlagVeryVerbose,
 		},
+		After: func(c *cli.Context) error {
+			if r := recover(); r != nil {
+				// Generate report in LOTUS_PATH and re-raise panic
+				build.GeneratePanicReport(c.String("panic-reports"), c.String("repo"), c.App.Name)
+				panic(r)
+			}
+			return nil
+		},
 
 		Commands: append(local, lcli.Commands...),
 	}

go.mod

@@ -63,6 +63,7 @@ require (
 	github.com/hannahhoward/go-pubsub v0.0.0-20200423002714-8d62886cc36e
 	github.com/hashicorp/go-multierror v1.1.0
 	github.com/hashicorp/golang-lru v0.5.4
+	github.com/icza/backscanner v0.0.0-20210726202459-ac2ffc679f94
 	github.com/influxdata/influxdb1-client v0.0.0-20191209144304-8bf82d3c094d
 	github.com/ipfs/bbloom v0.0.4
 	github.com/ipfs/go-bitswap v0.3.4

go.sum

@@ -571,6 +571,10 @@ github.com/iancoleman/orderedmap v0.1.0 h1:2orAxZBJsvimgEBmMWfXaFlzSG2fbQil5qzP3
 github.com/iancoleman/orderedmap v0.1.0/go.mod h1:N0Wam8K1arqPXNWjMo21EXnBPOPp36vB07FNRdD2geA=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
 github.com/icrowley/fake v0.0.0-20180203215853-4178557ae428/go.mod h1:uhpZMVGznybq1itEKXj6RYw9I71qK4kH+OGMjRC4KEo=
+github.com/icza/backscanner v0.0.0-20210726202459-ac2ffc679f94 h1:9tcYMdi+7Rb1y0E9Del1DRHui7Ne3za5lLw6CjMJv/M=
+github.com/icza/backscanner v0.0.0-20210726202459-ac2ffc679f94/go.mod h1:GYeBD1CF7AqnKZK+UCytLcY3G+UKo0ByXX/3xfdNyqQ=
+github.com/icza/mighty v0.0.0-20180919140131-cfd07d671de6 h1:8UsGZ2rr2ksmEru6lToqnXgA8Mz1DP11X4zSJ159C3k=
+github.com/icza/mighty v0.0.0-20180919140131-cfd07d671de6/go.mod h1:xQig96I1VNBDIWGCdTt54nHt6EeI639SmHycLYL7FkA=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/influxdata/influxdb1-client v0.0.0-20191209144304-8bf82d3c094d h1:/WZQPMZNsjZ7IlCpsLGdQBINg5bxKQ1K1sh6awxLtkA=
 github.com/influxdata/influxdb1-client v0.0.0-20191209144304-8bf82d3c094d/go.mod h1:qj24IKcXYK6Iy9ceXlo3Tc+vtHo9lIhSX5JddghvEPo=