chore: add degradable error

metricbeat/module/system/process/process.go

@@ -20,7 +20,6 @@
 package process
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"runtime"
@@ -31,11 +30,9 @@ import (
 	"github.com/elastic/elastic-agent-system-metrics/metric/system/cgroup"
 	"github.com/elastic/elastic-agent-system-metrics/metric/system/process"
 	"github.com/elastic/elastic-agent-system-metrics/metric/system/resolve"
-	"github.com/joeshaw/multierror"
 )
 
 var debugf = logp.NewLogger("system.process").Debugf
-var typeMultiError *multierror.MultiError
 
 func init() {
 	mb.Registry.MustAddMetricSet("system", "process", New,
@@ -114,7 +111,7 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) error {
 	// monitor either a single PID, or the configured set of processes.
 	if m.setpid == 0 {
 		procs, roots, err := m.stats.Get()
-		if errors.As(err, &typeMultiError) && err != nil {
+		if err != nil && !process.IsDegradable(err) {
 			return fmt.Errorf("process stats: %w", err)
 		}
 
@@ -124,7 +121,7 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) error {
 				RootFields:      roots[evtI],
 			})
 			if !isOpen {
-				return nil
+				return err
 			}
 		}
 		return err
@@ -137,6 +134,7 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) error {
 			MetricSetFields: proc,
 			RootFields:      root,
 		})
-		return err
 	}
+
+	return nil
 }

metricbeat/module/system/process/process_test.go

@@ -37,13 +37,17 @@ func TestFetch(t *testing.T) {
 
 	f := mbtest.NewReportingMetricSetV2Error(t, getConfig())
 	events, errs := mbtest.ReportingFetchV2Error(f)
-	assert.Empty(t, errs)
+	for _, err := range errs {
+		assert.True(t, process.IsDegradable(err))
+	}
 	assert.NotEmpty(t, events)
 
 	time.Sleep(2 * time.Second)
 
 	events, errs = mbtest.ReportingFetchV2Error(f)
-	assert.Empty(t, errs)
+	for _, err := range errs {
+		assert.True(t, process.IsDegradable(err))
+	}
 	assert.NotEmpty(t, events)
 
 	t.Logf("fetched %d events, showing events[0]:", len(events))