Add IPv4 address usage and quota metrics per subnet

AGENTS.md

@@ -109,6 +109,8 @@ AWS Resource Exporter is a Prometheus exporter for AWS resources, built in Go. I
 - `aws_resources_exporter_vpc_routesperroutetable_usage` - Usage of routes per route table
 - `aws_resources_exporter_vpc_ipv4blockspervpc_quota` - Quota for IPv4 blocks per VPC
 - `aws_resources_exporter_vpc_ipv4blockspervpc_usage` - Usage of IPv4 blocks per VPC
+- `aws_resources_exporter_vpc_ipv4addressespersubnet_capacity` - Amount of usable IPv4 addresses per subnet (based on CIDR block)
+- `aws_resources_exporter_vpc_ipv4addressespersubnet_usage` - Used IPv4 addresses per subnet
 
 ### EC2 Metrics
 - `aws_resources_exporter_ec2_transitgatewaysperregion_quota` - Quota for transit gateways per region

README.md

@@ -21,6 +21,7 @@ This was made as a complement to [CloudWatch Exporter](https://github.com/promet
 | VPC     | routetablespervpc           | Quota and usage of routetables per VPC              |
 | VPC     | routesperroutetable         | Quota and usage of the routes per routetable        |
 | VPC     | ipv4blockspervpc            | Quota and usage of ipv4 blocks per VPC              |
+| VPC     | ipv4addressespersubnet      | Capacity and usage of IPv4 addresses per subnet        |
 | EC2     | transitgatewaysperregion    | Quota and usage of transitgateways per region       |
 | Route53 | recordsperhostedzone        | Quota and usage of resource records per Hosted Zone |
 

dashboards/aws-resource-exporter.yaml

@@ -735,12 +735,258 @@ data:
           "type": "alertlist"
         },
         {
+          "collapsed": false,
           "gridPos": {
             "h": 1,
             "w": 24,
             "x": 0,
             "y": 32
           },
+          "id": 17,
+          "panels": [],
+          "title": "VPC",
+          "type": "row"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${datasource}"
+          },
+          "description": "Shows IPv4 address utilization per subnet",
+          "fieldConfig": {
+            "defaults": {
+              "color": {
+                "mode": "palette-classic"
+              },
+              "custom": {
+                "axisCenteredZero": false,
+                "axisColorMode": "text",
+                "axisLabel": "",
+                "axisPlacement": "auto",
+                "barAlignment": 0,
+                "drawStyle": "line",
+                "fillOpacity": 10,
+                "gradientMode": "none",
+                "hideFrom": {
+                  "legend": false,
+                  "tooltip": false,
+                  "viz": false
+                },
+                "lineInterpolation": "linear",
+                "lineWidth": 1,
+                "pointSize": 5,
+                "scaleDistribution": {
+                  "type": "linear"
+                },
+                "showPoints": "never",
+                "spanNulls": false,
+                "stacking": {
+                  "group": "A",
+                  "mode": "none"
+                },
+                "thresholdsStyle": {
+                  "mode": "off"
+                }
+              },
+              "mappings": [],
+              "thresholds": {
+                "mode": "absolute",
+                "steps": [
+                  {
+                    "color": "green",
+                    "value": null
+                  },
+                  {
+                    "color": "red",
+                    "value": 80
+                  }
+                ]
+              },
+              "unit": "short"
+            },
+            "overrides": []
+          },
+          "gridPos": {
+            "h": 8,
+            "w": 12,
+            "x": 0,
+            "y": 33
+          },
+          "id": 18,
+          "options": {
+            "legend": {
+              "calcs": [],
+              "displayMode": "list",
+              "placement": "bottom",
+              "showLegend": true
+            },
+            "tooltip": {
+              "mode": "multi",
+              "sort": "none"
+            }
+          },
+          "pluginVersion": "10.4.1",
+          "targets": [
+            {
+              "datasource": {
+                "type": "prometheus",
+                "uid": "${datasource}"
+              },
+              "editorMode": "code",
+              "expr": "aws_resources_exporter_vpc_ipv4addressespersubnet_capacity",
+              "legendFormat": "{{subnetid}} capacity",
+              "range": true,
+              "refId": "A"
+            },
+            {
+              "datasource": {
+                "type": "prometheus",
+                "uid": "${datasource}"
+              },
+              "editorMode": "code",
+              "expr": "aws_resources_exporter_vpc_ipv4addressespersubnet_usage",
+              "legendFormat": "{{subnetid}} used",
+              "range": true,
+              "refId": "B"
+            }
+          ],
+          "title": "IPv4 Address Usage per Subnet",
+          "type": "timeseries"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${datasource}"
+          },
+          "description": "Shows percentage utilization of IPv4 addresses per subnet",
+          "fieldConfig": {
+            "defaults": {
+              "color": {
+                "mode": "thresholds"
+              },
+              "custom": {
+                "align": "auto",
+                "cellOptions": {
+                  "type": "color-background"
+                },
+                "filterable": true,
+                "inspect": false
+              },
+              "mappings": [],
+              "max": 100,
+              "min": 0,
+              "thresholds": {
+                "mode": "absolute",
+                "steps": [
+                  {
+                    "color": "green",
+                    "value": null
+                  },
+                  {
+                    "color": "yellow",
+                    "value": 70
+                  },
+                  {
+                    "color": "red",
+                    "value": 90
+                  }
+                ]
+              },
+              "unit": "percent"
+            },
+            "overrides": []
+          },
+          "gridPos": {
+            "h": 8,
+            "w": 12,
+            "x": 12,
+            "y": 33
+          },
+          "id": 19,
+          "options": {
+            "cellHeight": "sm",
+            "footer": {
+              "countRows": false,
+              "enablePagination": false,
+              "fields": "",
+              "reducer": [
+                "sum"
+              ],
+              "show": false
+            },
+            "showHeader": true,
+            "sortBy": [
+              {
+                "desc": true,
+                "displayName": "Utilization %"
+              }
+            ]
+          },
+          "pluginVersion": "10.4.1",
+          "targets": [
+            {
+              "datasource": {
+                "type": "prometheus",
+                "uid": "${datasource}"
+              },
+              "editorMode": "code",
+              "expr": "(aws_resources_exporter_vpc_ipv4addressespersubnet_usage / aws_resources_exporter_vpc_ipv4addressespersubnet_capacity) * 100",
+              "format": "table",
+              "legendFormat": "__auto",
+              "range": true,
+              "refId": "A"
+            }
+          ],
+          "title": "Subnet IPv4 Utilization",
+          "transformations": [
+            {
+              "id": "groupBy",
+              "options": {
+                "fields": {
+                  "Value": {
+                    "aggregations": [
+                      "lastNotNull"
+                    ],
+                    "operation": "aggregate"
+                  },
+                  "aws_region": {
+                    "aggregations": [],
+                    "operation": "groupby"
+                  },
+                  "subnetid": {
+                    "aggregations": [],
+                    "operation": "groupby"
+                  },
+                  "vpcid": {
+                    "aggregations": [],
+                    "operation": "groupby"
+                  }
+                }
+              }
+            },
+            {
+              "id": "organize",
+              "options": {
+                "excludeByName": {},
+                "indexByName": {},
+                "renameByName": {
+                  "Value (lastNotNull)": "Utilization %",
+                  "aws_region": "Region",
+                  "subnetid": "Subnet ID",
+                  "vpcid": "VPC ID"
+                }
+              }
+            }
+          ],
+          "type": "table"
+        },
+        {
+          "gridPos": {
+            "h": 1,
+            "w": 24,
+            "x": 0,
+            "y": 41
+          },
           "id": 4,
           "title": "Route53",
           "type": "row"
@@ -806,7 +1052,7 @@ data:
             "h": 8,
             "w": 24,
             "x": 0,
-            "y": 33
+            "y": 42
           },
           "id": 2,
           "options": {

pkg/util.go

@@ -2,6 +2,7 @@ package pkg
 
 import (
 	"errors"
+	"net"
 	"os"
 	"sort"
 	"strconv"
@@ -61,3 +62,25 @@ func GetEOLStatus(eol string, thresholds []Threshold) (string, error) {
 	}
 	return thresholds[len(thresholds)-1].Name, nil
 }
+
+// CalculateTotalIPsFromCIDR calculates the total number of IP addresses in a CIDR block using Go's net package
+func CalculateTotalIPsFromCIDR(cidrBlock string) (int64, error) {
+	_, ipNet, err := net.ParseCIDR(cidrBlock)
+	if err != nil {
+		return 0, err
+	}
+
+	// Get the prefix length
+	prefixLength, _ := ipNet.Mask.Size()
+
+	// Validate reasonable prefix length for IPv4 subnets (AWS supports /16 to /28)
+	if prefixLength < 16 || prefixLength > 28 {
+		return 0, errors.New("invalid subnet prefix length for AWS (must be /16 to /28)")
+	}
+
+	// For IPv4, calculate 2^(32-prefix_length)
+	hostBits := 32 - prefixLength
+	totalIPs := int64(1 << hostBits)
+
+	return totalIPs, nil
+}