plugin/geoip - Support for ISO 3166-2 subdivisions. (#7728)

Metadata `geoip/subdivisions/code` now available if geoip plugin is used.

Signed-off-by: Tomas Boros <tomas.boros92@gmail.com>

plugin/geoip/README.md

@@ -141,6 +141,7 @@ A limited set of fields will be exported as labels, all values are stored using
 | `geoip/longitude`                    | `float64` | `0.1315`         | Base 10, max available precision.
 | `geoip/timezone`                     | `string`  | `Europe/London`  | The timezone.
 | `geoip/postalcode`                   | `string`  | `CB4`            | The postal code.
+| `geoip/subdivisions/code`            | `string`  | `ENG,TWH`        | Comma separated [ISO 3166-2](https://en.wikipedia.org/wiki/ISO_3166-2) subdivision(region) codes, e.g. first level (province), second level (state).
 | `geoip/asn/number`                   | `uint`    | `396982`         | The autonomous system number.
 | `geoip/asn/org`                      | `string`  | `GOOGLE-CLOUD-PLATFORM` | The autonomous system organization.
 

plugin/geoip/city.go

@@ -3,6 +3,7 @@ package geoip
 import (
 	"context"
 	"strconv"
+	"strings"
 
 	"github.com/coredns/coredns/plugin/metadata"
 
@@ -30,6 +31,18 @@ func (g GeoIP) setCityMetadata(ctx context.Context, data *geoip2.City) {
 	metadata.SetValueFunc(ctx, pluginName+"/country/code", func() string {
 		return countryCode
 	})
+
+	// Subdivisions represent administrative divisions (e.g., provinces, states) and are provided
+	// by the MaxMind database as a hierarchical list of up to 2 levels, ISO codes are set in metadata as
+	// a comma separated string, with the exact values provided by the database, even if those were empty strings.
+	subdivisionCodes := make([]string, 0, len(data.Subdivisions))
+	for _, sub := range data.Subdivisions {
+		subdivisionCodes = append(subdivisionCodes, sub.IsoCode)
+	}
+	metadata.SetValueFunc(ctx, pluginName+"/subdivisions/code", func() string {
+		return strings.Join(subdivisionCodes, ",")
+	})
+
 	isInEurope := strconv.FormatBool(data.Country.IsInEuropeanUnion)
 	metadata.SetValueFunc(ctx, pluginName+"/country/is_in_european_union", func() string {
 		return isInEurope

plugin/geoip/geoip_test.go

@@ -32,6 +32,7 @@ func TestMetadata(t *testing.T) {
 		{"geoip/longitude", "0.1315", cityDBPath, "81.2.69.142"},
 		{"geoip/timezone", "Europe/London", cityDBPath, "81.2.69.142"},
 		{"geoip/postalcode", "CB4", cityDBPath, "81.2.69.142"},
+		{"geoip/subdivisions/code", "ENG,CAM", cityDBPath, "81.2.69.142"},
 
 		// ASN database tests
 		{"geoip/asn/number", "12345", asnDBPath, "81.2.69.142"},