Add Sentry Spans for Bash execution.

internal/nomad/sentry_debug_writer.go

@@ -0,0 +1,89 @@
+package nomad
+
+import (
+	"context"
+	"fmt"
+	"github.com/getsentry/sentry-go"
+	"io"
+	"regexp"
+	"strconv"
+	"time"
+)
+
+const (
+	// timeDebugMessageFormat is the format of messages that will be converted to debug messages.
+	timeDebugMessageFormat = "echo -ne \"\\x1EPoseidon %s $(date +%%s%%3N)\\x1E\""
+	// Format Parameters: 1. Debug Comment, 2. command.
+	timeDebugMessageFormatStart = timeDebugMessageFormat + "; %s"
+	// Format Parameters: 1. command, 2. Debug Comment.
+	timeDebugMessageFormatEnd = "%s && " + timeDebugMessageFormat
+
+	timeDebugMessagePatternGroupText = 1
+	timeDebugMessagePatternGroupTime = 2
+)
+
+var (
+	timeDebugMessagePattern      = regexp.MustCompile(`\x1EPoseidon (?P<text>\w+) (?P<time>\d+)\x1E`)
+	timeDebugMessagePatternStart = regexp.MustCompile(`\x1EPoseidon`)
+)
+
+// SentryDebugWriter is scanning the input for the debug message pattern.
+// For matches, it creates a Sentry Span. Otherwise, the data will be forwarded to the Target.
+// The passed context Ctx should contain the Sentry data.
+type SentryDebugWriter struct {
+	Target   io.Writer
+	Ctx      context.Context
+	lastSpan *sentry.Span
+}
+
+// Improve: Handling of a split debug messages (usually p is exactly one debug message, not less and not more).
+func (s *SentryDebugWriter) Write(p []byte) (n int, err error) {
+	if !timeDebugMessagePatternStart.Match(p) {
+		count, err := s.Target.Write(p)
+		if err != nil {
+			err = fmt.Errorf("SentryDebugWriter Forwarded: %w", err)
+		}
+		return count, err
+	}
+
+	loc := timeDebugMessagePattern.FindIndex(p)
+	if loc == nil {
+		log.WithField("data", p).Warn("Exec debug message could not be read completely")
+		return 0, nil
+	}
+
+	go s.handleTimeDebugMessage(p[loc[0]:loc[1]])
+
+	debugMessageLength := loc[1] - loc[0]
+	if debugMessageLength < len(p) {
+		count, err := s.Write(append(p[0:loc[0]], p[loc[1]:]...))
+		return debugMessageLength + count, err
+	} else {
+		return debugMessageLength, nil
+	}
+}
+
+func (s *SentryDebugWriter) handleTimeDebugMessage(message []byte) {
+	if s.lastSpan != nil {
+		s.lastSpan.Finish()
+	}
+
+	matches := timeDebugMessagePattern.FindSubmatch(message)
+	if matches == nil {
+		log.WithField("msg", message).Error("Cannot parse passed time debug message")
+		return
+	}
+
+	timestamp, err := strconv.ParseInt(string(matches[timeDebugMessagePatternGroupTime]), 10, 64)
+	if err != nil {
+		log.WithField("matches", matches).Warn("Could not parse Unix timestamp")
+		return
+	}
+	s.lastSpan = sentry.StartSpan(s.Ctx, "nomad.execute.pipe")
+	s.lastSpan.Description = string(matches[timeDebugMessagePatternGroupText])
+	s.lastSpan.StartTime = time.UnixMilli(timestamp)
+	s.lastSpan.Finish()
+
+	s.lastSpan = sentry.StartSpan(s.Ctx, "nomad.execute.bash")
+	s.lastSpan.Description = string(matches[timeDebugMessagePatternGroupText])
+}