Fix elasticsearch v8 cluster_settings unmarshal error

Closes #840

collector/cluster_settings.go

@@ -103,49 +103,6 @@ var clusterSettingsDesc = map[string]*prometheus.Desc{
 	),
 }
 
-// clusterSettingsResponse is a representation of a Elasticsearch Cluster Settings
-type clusterSettingsResponse struct {
-	Defaults   clusterSettingsSection `json:"defaults"`
-	Persistent clusterSettingsSection `json:"persistent"`
-	Transient  clusterSettingsSection `json:"transient"`
-}
-
-// clusterSettingsSection is a representation of a Elasticsearch Cluster Settings
-type clusterSettingsSection struct {
-	Cluster clusterSettingsCluster `json:"cluster"`
-}
-
-// clusterSettingsCluster is a representation of a Elasticsearch clusterSettingsCluster Settings
-type clusterSettingsCluster struct {
-	Routing clusterSettingsRouting `json:"routing"`
-	// This can be either a JSON object (which does not contain the value we are interested in) or a string
-	MaxShardsPerNode interface{} `json:"max_shards_per_node"`
-}
-
-// clusterSettingsRouting is a representation of a Elasticsearch Cluster shard routing configuration
-type clusterSettingsRouting struct {
-	Allocation clusterSettingsAllocation `json:"allocation"`
-}
-
-// clusterSettingsAllocation is a representation of a Elasticsearch Cluster shard routing allocation settings
-type clusterSettingsAllocation struct {
-	Enabled string              `json:"enable"`
-	Disk    clusterSettingsDisk `json:"disk"`
-}
-
-// clusterSettingsDisk is a representation of a Elasticsearch Cluster shard routing disk allocation settings
-type clusterSettingsDisk struct {
-	ThresholdEnabled string                   `json:"threshold_enabled"`
-	Watermark        clusterSettingsWatermark `json:"watermark"`
-}
-
-// clusterSettingsWatermark is representation of Elasticsearch Cluster shard routing disk allocation watermark settings
-type clusterSettingsWatermark struct {
-	FloodStage string `json:"flood_stage"`
-	High       string `json:"high"`
-	Low        string `json:"low"`
-}
-
 func (c *ClusterSettingsCollector) Update(ctx context.Context, ch chan<- prometheus.Metric) error {
 	u := c.u.ResolveReference(&url.URL{Path: "_cluster/settings"})
 	q := u.Query()
@@ -185,15 +142,12 @@ func (c *ClusterSettingsCollector) Update(ctx context.Context, ch chan<- prometh
 	}
 
 	// Max shards per node
-	if maxShardsPerNodeString, ok := merged.Cluster.MaxShardsPerNode.(string); ok {
-		maxShardsPerNode, err := strconv.ParseInt(maxShardsPerNodeString, 10, 64)
-		if err == nil {
-			ch <- prometheus.MustNewConstMetric(
-				clusterSettingsDesc["maxShardsPerNode"],
-				prometheus.GaugeValue,
-				float64(maxShardsPerNode),
-			)
-		}
+	if maxShardsPerNode, err := strconv.ParseInt(merged.Cluster.MaxShardsPerNode, 10, 64); err == nil {
+		ch <- prometheus.MustNewConstMetric(
+			clusterSettingsDesc["maxShardsPerNode"],
+			prometheus.GaugeValue,
+			float64(maxShardsPerNode),
+		)
 	}
 
 	// Shard allocation enabled

collector/cluster_settings_response.go

@@ -0,0 +1,87 @@
+// Copyright 2021 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package collector
+
+import (
+	"encoding/json"
+	"github.com/mitchellh/mapstructure"
+)
+
+// clusterSettingsResponse is a representation of a Elasticsearch Cluster Settings
+type clusterSettingsResponse struct {
+	Defaults   clusterSettingsSection `json:"defaults"`
+	Persistent clusterSettingsSection `json:"persistent"`
+	Transient  clusterSettingsSection `json:"transient"`
+}
+
+// clusterSettingsSection is a representation of a Elasticsearch Cluster Settings
+type clusterSettingsSection struct {
+	Cluster clusterSettingsCluster `json:"cluster" mapstructure:",squash"`
+}
+
+// clusterSettingsCluster is a representation of a Elasticsearch clusterSettingsCluster Settings
+type clusterSettingsCluster struct {
+	Routing clusterSettingsRouting `json:"routing" mapstructure:",squash"`
+
+	MaxShardsPerNode string `json:"max_shards_per_node" mapstructure:"cluster.max_shards_per_node"`
+}
+
+// clusterSettingsRouting is a representation of a Elasticsearch Cluster shard routing configuration
+type clusterSettingsRouting struct {
+	Allocation clusterSettingsAllocation `json:"allocation" mapstructure:",squash"`
+}
+
+// clusterSettingsAllocation is a representation of a Elasticsearch Cluster shard routing allocation settings
+type clusterSettingsAllocation struct {
+	Enabled string              `json:"enable" mapstructure:"cluster.routing.allocation.enable"`
+	Disk    clusterSettingsDisk `json:"disk" mapstructure:",squash"`
+}
+
+// clusterSettingsDisk is a representation of a Elasticsearch Cluster shard routing disk allocation settings
+type clusterSettingsDisk struct {
+	ThresholdEnabled string                   `json:"threshold_enabled" mapstructure:"cluster.routing.allocation.disk.threshold_enabled"`
+	Watermark        clusterSettingsWatermark `json:"watermark" mapstructure:",squash"`
+}
+
+// clusterSettingsWatermark is representation of Elasticsearch Cluster shard routing disk allocation watermark settings
+type clusterSettingsWatermark struct {
+	FloodStage string `json:"flood_stage" mapstructure:"cluster.routing.allocation.disk.watermark.flood_stage"`
+	High       string `json:"high" mapstructure:"cluster.routing.allocation.disk.watermark.high"`
+	Low        string `json:"low" mapstructure:"cluster.routing.allocation.disk.watermark.low"`
+}
+
+func (c *clusterSettingsSection) UnmarshalJSON(data []byte) error {
+	var settings map[string]interface{}
+
+	if err := json.Unmarshal(data, &settings); err != nil {
+		return err
+	}
+
+	settings = flatten(settings)
+	return mapstructure.Decode(settings, c)
+}
+
+func flatten(m map[string]interface{}) map[string]interface{} {
+	result := make(map[string]interface{})
+	for k1, v1 := range m {
+		if n, ok := v1.(map[string]interface{}); ok {
+			for k2, v2 := range flatten(n) {
+				result[k1+"."+k2] = v2
+			}
+		} else {
+			result[k1] = v1
+		}
+	}
+	return result
+}

collector/cluster_settings_test.go

@@ -114,6 +114,30 @@ elasticsearch_clustersettings_allocation_watermark_high_bytes 2.147483648e+11
 # HELP elasticsearch_clustersettings_allocation_watermark_low_bytes Low watermark for disk usage in bytes.
 # TYPE elasticsearch_clustersettings_allocation_watermark_low_bytes gauge
 elasticsearch_clustersettings_allocation_watermark_low_bytes 5.24288e+07
+`,
+		},
+		{
+			name: "8.10.4",
+			file: "../fixtures/settings-8.10.4.json",
+			want: `
+# HELP elasticsearch_clustersettings_stats_max_shards_per_node Current maximum number of shards per node setting.
+# TYPE elasticsearch_clustersettings_stats_max_shards_per_node gauge
+elasticsearch_clustersettings_stats_max_shards_per_node 1000
+# HELP elasticsearch_clustersettings_stats_shard_allocation_enabled Current mode of cluster wide shard routing allocation settings.
+# TYPE elasticsearch_clustersettings_stats_shard_allocation_enabled gauge
+elasticsearch_clustersettings_stats_shard_allocation_enabled 0
+# HELP elasticsearch_clustersettings_allocation_threshold_enabled Is disk allocation decider enabled.
+# TYPE elasticsearch_clustersettings_allocation_threshold_enabled gauge
+elasticsearch_clustersettings_allocation_threshold_enabled 1
+# HELP elasticsearch_clustersettings_allocation_watermark_flood_stage_ratio Flood stage watermark as a ratio.
+# TYPE elasticsearch_clustersettings_allocation_watermark_flood_stage_ratio gauge
+elasticsearch_clustersettings_allocation_watermark_flood_stage_ratio 0.95
+# HELP elasticsearch_clustersettings_allocation_watermark_high_ratio High watermark for disk usage as a ratio.
+# TYPE elasticsearch_clustersettings_allocation_watermark_high_ratio gauge
+elasticsearch_clustersettings_allocation_watermark_high_ratio 0.9
+# HELP elasticsearch_clustersettings_allocation_watermark_low_ratio Low watermark for disk usage as a ratio.
+# TYPE elasticsearch_clustersettings_allocation_watermark_low_ratio gauge
+elasticsearch_clustersettings_allocation_watermark_low_ratio 0.85
 `,
 		},
 	}