Don't fail parsing of zpool stats if pool health is UNAVAIL on FreeBSD (#3149)

(cherry picked from commit 0502b65316)

plugins/inputs/zfs/zfs_freebsd.go

@@ -33,6 +33,12 @@ func (z *Zfs) gatherPoolStats(acc telegraf.Accumulator) (string, error) {
 			tags := map[string]string{"pool": col[0], "health": col[8]}
 			fields := map[string]interface{}{}
 
+			if tags["health"] == "UNAVAIL" {
+
+				fields["size"] = int64(0)
+
+			} else {
+
 				size, err := strconv.ParseInt(col[1], 10, 64)
 				if err != nil {
 					return "", fmt.Errorf("Error parsing size: %s", err)
@@ -68,6 +74,7 @@ func (z *Zfs) gatherPoolStats(acc telegraf.Accumulator) (string, error) {
 					return "", fmt.Errorf("Error parsing dedupratio: %s", err)
 				}
 				fields["dedupratio"] = dedup
+			}
 
 			acc.AddFields("zfs_pool", fields, tags)
 		}

plugins/inputs/zfs/zfs_freebsd_test.go

@@ -22,6 +22,15 @@ func mock_zpool() ([]string, error) {
 	return zpool_output, nil
 }
 
+// $ zpool list -Hp
+var zpool_output_unavail = []string{
+	"temp2	-	-	-	-	-	-	-	UNAVAIL	-",
+}
+
+func mock_zpool_unavail() ([]string, error) {
+	return zpool_output_unavail, nil
+}
+
 // sysctl -q kstat.zfs.misc.arcstats
 
 // sysctl -q kstat.zfs.misc.vdev_cache_stats
@@ -82,6 +91,41 @@ func TestZfsPoolMetrics(t *testing.T) {
 	acc.AssertContainsTaggedFields(t, "zfs_pool", poolMetrics, tags)
 }
 
+func TestZfsPoolMetrics_unavail(t *testing.T) {
+
+	var acc testutil.Accumulator
+
+	z := &Zfs{
+		KstatMetrics: []string{"vdev_cache_stats"},
+		sysctl:       mock_sysctl,
+		zpool:        mock_zpool_unavail,
+	}
+	err := z.Gather(&acc)
+	require.NoError(t, err)
+
+	require.False(t, acc.HasMeasurement("zfs_pool"))
+	acc.Metrics = nil
+
+	z = &Zfs{
+		KstatMetrics: []string{"vdev_cache_stats"},
+		PoolMetrics:  true,
+		sysctl:       mock_sysctl,
+		zpool:        mock_zpool_unavail,
+	}
+	err = z.Gather(&acc)
+	require.NoError(t, err)
+
+	//one pool, UNAVAIL
+	tags := map[string]string{
+		"pool":   "temp2",
+		"health": "UNAVAIL",
+	}
+
+	poolMetrics := getTemp2PoolMetrics()
+
+	acc.AssertContainsTaggedFields(t, "zfs_pool", poolMetrics, tags)
+}
+
 func TestZfsGeneratesMetrics(t *testing.T) {
 	var acc testutil.Accumulator
 
@@ -128,6 +172,12 @@ func getFreeNasBootPoolMetrics() map[string]interface{} {
 	}
 }
 
+func getTemp2PoolMetrics() map[string]interface{} {
+	return map[string]interface{}{
+		"size": int64(0),
+	}
+}
+
 func getKstatMetricsVdevOnly() map[string]interface{} {
 	return map[string]interface{}{
 		"vdev_cache_stats_misses":      int64(87789),