fix(exec): preserve child exit code when OTLP export fails (#360)

SoftFail called os.Exit(0) or os.Exit(1) regardless of the child
process exit code. When exec ran a command that exited 42, then OTLP
export failed, the exit code was lost.

Two changes:
1. Capture Diag.ExecExitCode before OTLP export (was after)
2. SoftFail checks Diag.ExecExitCode and uses it when non-zero

Fixes #360

🤖 Claude <claude@anthropic.com>

Author: tobert

data_for_test.go

@@ -568,6 +568,32 @@ var suites = []FixtureSuite{
 			},
 		},
 	},
+	// #360: exec child exit code should propagate even when OTLP export fails
+	{
+		{
+			Name: "#360 exec child exit code preserved when export fails",
+			Config: FixtureConfig{
+				CliArgs: []string{"exec",
+					"--endpoint", "{{endpoint}}",
+					"--timeout", "100ms",
+					"--", "/bin/sh", "-c", "exit 42",
+				},
+				StopServerBeforeExec: true,
+				TestTimeoutMs:        2000,
+				IsLongTest:           true,
+			},
+			Expect: Results{
+				Config: otelcli.DefaultConfig(),
+			},
+			CheckFuncs: []CheckFunc{
+				func(t *testing.T, f Fixture, r Results) {
+					if r.ExitCode != 42 {
+						t.Errorf("expected exit code 42 from child process, got %d", r.ExitCode)
+					}
+				},
+			},
+		},
+	},
 	// otel-cli span with no OTLP config should do and print nothing
 	{
 		{

otelcli/config.go

@@ -373,11 +373,16 @@ func (c Config) SoftLogIfErr(err error) {
 }
 
 // SoftFail calls through to softLog (which logs only if otel-cli was run with the --verbose
-// flag), then immediately exits - with status -1 by default, or 1 if --fail was
-// set (a la `curl --fail`)
+// flag), then immediately exits. When a child process exit code has been captured (e.g. from
+// exec), that code is preserved. Otherwise exits 0 by default, or 1 with --fail.
 func (c Config) SoftFail(format string, a ...interface{}) {
 	c.SoftLog(format, a...)
 
+	// preserve exec child exit code when available (#360)
+	if Diag.ExecExitCode != 0 {
+		os.Exit(Diag.ExecExitCode)
+	}
+
 	if c.Fail {
 		os.Exit(1)
 	} else {

otelcli/exec.go

@@ -152,6 +152,13 @@ func doExec(cmd *cobra.Command, args []string) {
 		span.Attributes = append(span.Attributes, pidAttrs...)
 	}
 
+	// capture the child's exit code before OTLP export so SoftFail can use it (#360)
+	if child.ProcessState != nil {
+		Diag.ExecExitCode = child.ProcessState.ExitCode()
+	} else {
+		Diag.ExecExitCode = 127
+	}
+
 	cancelCtxDeadline()
 	close(signals)
 	<-signalsDone
@@ -171,16 +178,6 @@ func doExec(cmd *cobra.Command, args []string) {
 		config.SoftFail("client.Stop() failed: %s", err)
 	}
 
-	// set the global exit code so main() can grab it and os.Exit() properly
-	// ProcessState is nil if the command failed to start
-	if child.ProcessState != nil {
-		Diag.ExecExitCode = child.ProcessState.ExitCode()
-	} else {
-		// command failed to start (e.g., command not found)
-		// use exit code 127 to match shell behavior for "command not found"
-		Diag.ExecExitCode = 127
-	}
-
 	config.PropagateTraceparent(span, os.Stdout)
 }