fix: discover mounted geoip db files (#7228)

* fix: discover mounted geoip db files

* add test

* fix runtime reload of config.MaxmindEditionFiles

* add e2e test

* log missing geoip2 db

internal/nginx/maxmind_test.go

@@ -0,0 +1,75 @@
+/*
+Copyright 2020 The Kubernetes 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 nginx
+
+import (
+	"reflect"
+	"testing"
+)
+
+func resetForTesting() {
+	fileExists = _fileExists
+	MaxmindLicenseKey = ""
+	MaxmindEditionIDs = ""
+	MaxmindEditionFiles = []string{}
+	MaxmindMirror = ""
+}
+
+func TestGeoLite2DBExists(t *testing.T) {
+	tests := []struct {
+		name      string
+		setup     func()
+		want      bool
+		wantFiles []string
+	}{
+		{
+			name:      "empty",
+			wantFiles: []string{},
+		},
+		{
+			name: "existing files",
+			setup: func() {
+				MaxmindEditionIDs = "GeoLite2-City,GeoLite2-ASN"
+				fileExists = func(string) bool {
+					return true
+				}
+			},
+			want:      true,
+			wantFiles: []string{"GeoLite2-City.mmdb", "GeoLite2-ASN.mmdb"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			resetForTesting()
+			// mimics assignment in flags.go
+			config := &MaxmindEditionFiles
+
+			if tt.setup != nil {
+				tt.setup()
+			}
+			if got := GeoLite2DBExists(); got != tt.want {
+				t.Errorf("GeoLite2DBExists() = %v, want %v", got, tt.want)
+			}
+			if !reflect.DeepEqual(MaxmindEditionFiles, tt.wantFiles) {
+				t.Errorf("nginx.MaxmindEditionFiles = %v, want %v", MaxmindEditionFiles, tt.wantFiles)
+			}
+			if !reflect.DeepEqual(*config, tt.wantFiles) {
+				t.Errorf("config.MaxmindEditionFiles = %v, want %v", *config, tt.wantFiles)
+			}
+		})
+	}
+}