feat(agent): embed GeoLite2 City database

Initialize missing Country and City databases from embedded assets and use FyraLabs releases for periodic updates.

internal/apps/agent/geoipdata/data.go

@@ -1,12 +1,16 @@
-// Package geoipdata embeds the default MaxMind GeoLite2 country database.
+// Package geoipdata embeds the default MaxMind GeoLite2 databases.
 package geoipdata
 
 import "embed"
 
-// FS holds the embedded GeoLite2-Country.mmdb database.
+// FS holds the embedded GeoLite2 Country and City databases.
 //
-//go:embed GeoLite2-Country.mmdb
+//go:embed GeoLite2-Country.mmdb GeoLite2-City.mmdb
 var FS embed.FS
 
-// DefaultMMDBName is the filename of the embedded MaxMind country database.
-const DefaultMMDBName = "GeoLite2-Country.mmdb"
+const (
+	// DefaultMMDBName is the filename of the embedded MaxMind Country database.
+	DefaultMMDBName = "GeoLite2-Country.mmdb"
+	// DefaultCityMMDBName is the filename of the embedded MaxMind City database.
+	DefaultCityMMDBName = "GeoLite2-City.mmdb"
+)

internal/apps/agent/geoipdata/data_test.go

@@ -0,0 +1,38 @@
+package geoipdata
+
+import (
+	"io/fs"
+	"strings"
+	"testing"
+
+	"github.com/oschwald/maxminddb-golang"
+)
+
+func TestEmbeddedDatabasesAreValid(t *testing.T) {
+	tests := []struct {
+		name             string
+		filename         string
+		databaseTypePart string
+	}{
+		{name: "Country", filename: DefaultMMDBName, databaseTypePart: "Country"},
+		{name: "City", filename: DefaultCityMMDBName, databaseTypePart: "City"},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			data, err := fs.ReadFile(FS, test.filename)
+			if err != nil {
+				t.Fatalf("read embedded database: %v", err)
+			}
+			reader, err := maxminddb.FromBytes(data)
+			if err != nil {
+				t.Fatalf("open embedded database: %v", err)
+			}
+			defer reader.Close()
+
+			if !strings.Contains(reader.Metadata.DatabaseType, test.databaseTypePart) {
+				t.Fatalf("unexpected database type %q", reader.Metadata.DatabaseType)
+			}
+		})
+	}
+}