[Currency support] Adding a debug endpoint (prebid#822)

This CL introduces a new admin endpoint exposing current currency rate
converter internals such as:
- Sync source URL
- Internal rates
- Update frequency
- Last update

It will help for the future rollout of currencies support.

More details: prebid#280

currencies/constant_rates.go

@@ -34,3 +34,8 @@ func (r *ConstantRates) GetRate(from string, to string) (float64, error) {
 
 	return 1, nil
 }
+
+// GetRates returns current rates
+func (r *ConstantRates) GetRates() *map[string]map[string]float64 {
+	return nil
+}

currencies/converter_info.go

@@ -0,0 +1,45 @@
+package currencies
+
+import "time"
+
+// ConverterInfo holds information about converter setup
+type ConverterInfo interface {
+	Source() string
+	FetchingInterval() time.Duration
+	LastUpdated() time.Time
+	Rates() *map[string]map[string]float64
+	AdditionalInfo() interface{}
+}
+
+type converterInfo struct {
+	source           string
+	fetchingInterval time.Duration
+	lastUpdated      time.Time
+	rates            *map[string]map[string]float64
+	additionalInfo   interface{}
+}
+
+// Source returns converter's URL source
+func (ci converterInfo) Source() string {
+	return ci.source
+}
+
+// FetchingInterval returns converter's fetching interval in nanoseconds
+func (ci converterInfo) FetchingInterval() time.Duration {
+	return ci.fetchingInterval
+}
+
+// LastUpdated returns converter's last updated time
+func (ci converterInfo) LastUpdated() time.Time {
+	return ci.lastUpdated
+}
+
+// Rates returns converter's internal rates
+func (ci converterInfo) Rates() *map[string]map[string]float64 {
+	return ci.rates
+}
+
+// AdditionalInfo returns converter's additional infos
+func (ci converterInfo) AdditionalInfo() interface{} {
+	return ci.additionalInfo
+}

currencies/rate_converter.go

@@ -170,6 +170,16 @@ func (rc *RateConverter) Rates() Conversions {
 	return nil
 }
 
+// GetInfo returns setup information about the converter
+func (rc *RateConverter) GetInfo() ConverterInfo {
+	return converterInfo{
+		source:           rc.syncSourceURL,
+		fetchingInterval: rc.fetchingInterval,
+		lastUpdated:      rc.LastUpdated(),
+		rates:            rc.Rates().GetRates(),
+	}
+}
+
 type httpClient interface {
 	Do(req *http.Request) (*http.Response, error)
 }
@@ -179,4 +189,5 @@ type httpClient interface {
 // currencies, then an err is returned and rate is 0.
 type Conversions interface {
 	GetRate(from string, to string) (float64, error)
+	GetRates() *map[string]map[string]float64
 }

currencies/rates.go

@@ -69,3 +69,8 @@ func (r *Rates) GetRate(from string, to string) (float64, error) {
 	}
 	return 0, errors.New("rates are nil")
 }
+
+// GetRates returns current rates
+func (r *Rates) GetRates() *map[string]map[string]float64 {
+	return &r.Conversions
+}

docs/developers/currency-converter.md

@@ -48,4 +48,9 @@ This configuration can be changed:
 | 1                | USD           |             1 | NO                       |                         1 | YES       |
 | 1                | EUR           |          1.13 | YES                      |                      1.13 | YES       |
 | 1                | EUR           |           N/A | YES                      |                       N/A | NO        |
-| 1                | EUR           |          1.13 | NO                       |                       N/A | NO        |
+| 1                | EUR           |          1.13 | NO                       |                       N/A | NO        |
+
+## Debug
+
+A dedicated endpoint will allow you to see what's happening within the currency converter.
+See [currency rates endpoint](../endpoints/currency_rates.md) for more details.

docs/endpoints/currency_rates.md

@@ -0,0 +1,111 @@
+## `GET /currency/rates`
+
+This endpoint exposes active currency rate converter information in the server.
+Information are:
+- `info.active`: true if currency converter is active
+- `info.source`: URL from which rates are fetched
+- `info.fetchingIntervalNs`: Fetching interval from source in nanoseconds
+- `info.lastUpdated`: Datetime when the rates where updated
+- `info.rates`: Internal rates values
+
+### Sample responses
+#### Rate converter active
+```json
+{
+    "active": true,
+    "info": {
+        "source": "https://cdn.jsdelivr.net/gh/prebid/currency-file@1/latest.json",
+        "fetchingIntervalNs": 60000000000,
+        "lastUpdated": "2019-03-02T14:18:41.221063+01:00",
+        "rates": {
+            "GBP": {
+                "AUD": 1.8611576401,
+                "BGN": 2.2750325703,
+                "BRL": 5.0061650847,
+                "CAD": 1.7414619393,
+                "CHF": 1.3217708915,
+                "CNY": 8.8791178113,
+                "CZK": 29.8203982877,
+                "DKK": 8.6791596873,
+                "EUR": 1.163223525,
+                "GBP": 1,
+                "HKD": 10.3927042621,
+                "HRK": 8.645077238,
+                "HUF": 367.6484273218,
+                "IDR": 18689.5123766983,
+                "ILS": 4.8077191513,
+                "INR": 93.8663223525,
+                "ISK": 158.0820770519,
+                "JPY": 148.1365159129,
+                "KRW": 1491.3921459148,
+                "MXN": 25.5839382096,
+                "MYR": 5.394332775,
+                "NOK": 11.3144425833,
+                "NZD": 1.9374651033,
+                "PHP": 68.6139028476,
+                "PLN": 5.0130281035,
+                "RON": 5.5172855016,
+                "RUB": 87.2333891681,
+                "SEK": 12.2141959799,
+                "SGD": 1.7908989391,
+                "THB": 42.0074911595,
+                "TRY": 7.1224176438,
+                "USD": 1.3240973385,
+                "ZAR": 18.7774520752
+            },
+            "USD": {
+                "AUD": 1.4056048493,
+                "BGN": 1.7181762277,
+                "BRL": 3.7808134938,
+                "CAD": 1.3152068875,
+                "CHF": 0.9982429939,
+                "CNY": 6.705789335,
+                "CZK": 22.5213036985,
+                "DKK": 6.554774664,
+                "EUR": 0.8785030308,
+                "GBP": 0.7552314855,
+                "HKD": 7.8488974787,
+                "HRK": 6.5290345252,
+                "HUF": 277.6596679259,
+                "IDR": 14114.9081964333,
+                "ILS": 3.6309408767,
+                "INR": 70.8908020733,
+                "ISK": 119.3885618905,
+                "JPY": 111.8773609769,
+                "KRW": 1126.3463058948,
+                "MXN": 19.3217956602,
+                "MYR": 4.0739699552,
+                "NOK": 8.5450232803,
+                "NZD": 1.4632346482,
+                "PHP": 51.8193797769,
+                "PLN": 3.7859966617,
+                "RON": 4.1668277256,
+                "RUB": 65.8814020908,
+                "SEK": 9.2245453747,
+                "SGD": 1.3525432663,
+                "THB": 31.7253799526,
+                "TRY": 5.3790740578,
+                "USD": 1,
+                "ZAR": 14.1813230256
+            }
+        }
+    }
+}
+```
+
+#### Rate converter set with constant rates
+```json
+{
+    "active": true,
+    "source": "",
+    "fetchingIntervalNs": 0,
+    "lastUpdated": "0001-01-01T00:00:00Z"
+}
+```
+
+#### Rate converter not set
+```json
+{
+    "active": false
+}
+```

endpoints/currency_rates.go

@@ -0,0 +1,74 @@
+package endpoints
+
+import (
+	"encoding/json"
+	"net/http"
+	"time"
+
+	"github.com/golang/glog"
+	"github.com/prebid/prebid-server/currencies"
+)
+
+// currencyRatesInfo holds currency rates information.
+type currencyRatesInfo struct {
+	Active           bool                           `json:"active"`
+	Source           *string                        `json:"source,omitempty"`
+	FetchingInterval *time.Duration                 `json:"fetchingIntervalNs,omitempty"`
+	LastUpdated      *time.Time                     `json:"lastUpdated,omitempty"`
+	Rates            *map[string]map[string]float64 `json:"rates,omitempty"`
+	AdditionalInfo   interface{}                    `json:"additionalInfo,omitempty"`
+}
+
+type rateConverter interface {
+	GetInfo() currencies.ConverterInfo
+}
+
+// newCurrencyRatesInfo creates a new CurrencyRatesInfo instance.
+func newCurrencyRatesInfo(rateConverter rateConverter) currencyRatesInfo {
+
+	currencyRatesInfo := currencyRatesInfo{
+		Active: false,
+	}
+
+	if rateConverter == nil {
+		return currencyRatesInfo
+	}
+
+	currencyRatesInfo.Active = true
+
+	infos := rateConverter.GetInfo()
+	if infos == nil {
+		return currencyRatesInfo
+	}
+
+	source := infos.Source()
+	currencyRatesInfo.Source = &source
+
+	fetchingInterval := infos.FetchingInterval()
+	currencyRatesInfo.FetchingInterval = &fetchingInterval
+
+	lastUpdated := infos.LastUpdated()
+	currencyRatesInfo.LastUpdated = &lastUpdated
+
+	currencyRatesInfo.Rates = infos.Rates()
+	currencyRatesInfo.AdditionalInfo = infos.AdditionalInfo()
+
+	return currencyRatesInfo
+}
+
+// NewCurrencyRatesEndpoint returns current currency rates applied by the PBS server.
+func NewCurrencyRatesEndpoint(rateConverter rateConverter) func(w http.ResponseWriter, r *http.Request) {
+	currencyRateInfo := newCurrencyRatesInfo(rateConverter)
+
+	return func(w http.ResponseWriter, r *http.Request) {
+		jsonOutput, err := json.Marshal(currencyRateInfo)
+		if err != nil {
+			glog.Errorf("/currency/rates Critical error when trying to marshal currencyRateInfo: %v", err)
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		w.Write(jsonOutput)
+	}
+}