lazy-load ccxt exchange list, breaking hard dependency on ccxt-rest, c…

…loses #126 (#128)

cmd/exchanges.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/stellar/kelp/plugins"
+	"github.com/stellar/kelp/support/sdk"
 
 	"github.com/spf13/cobra"
 )
@@ -15,6 +16,8 @@ var exchanagesCmd = &cobra.Command{
 
 func init() {
 	exchanagesCmd.Run = func(ccmd *cobra.Command, args []string) {
+		// call sdk.GetExchangeList() here so we pre-load exchanges before displaying the table
+		sdk.GetExchangeList()
 		fmt.Printf("  Exchange\t\t\tTested\t\tTrading\t\tDescription\n")
 		fmt.Printf("  --------------------------------------------------------------------------------\n")
 		exchanges := plugins.Exchanges()

plugins/factory.go

@@ -165,15 +165,23 @@ type ExchangeContainer struct {
 }
 
 // exchanges is a map of all the exchange integrations available
-var exchanges map[string]ExchangeContainer
+var exchanges *map[string]ExchangeContainer
 
-func init() {
+// getExchanges returns a map of all the exchange integrations available
+func getExchanges() map[string]ExchangeContainer {
+	if exchanges == nil {
+		loadExchanges()
+	}
+	return *exchanges
+}
+
+func loadExchanges() {
 	// marked as tested if key exists in this map (regardless of bool value)
 	testedCcxtExchanges := map[string]bool{
 		"binance": true,
 	}
 
-	exchanges = map[string]ExchangeContainer{
+	exchanges = &map[string]ExchangeContainer{
 		"kraken": ExchangeContainer{
 			SortOrder:    0,
 			Description:  "Kraken is a popular centralized cryptocurrency exchange",
@@ -186,13 +194,13 @@ func init() {
 	}
 
 	// add all CCXT exchanges
-	sortOrderOffset := len(exchanges)
-	for i, exchangeName := range sdk.ExchangeList {
+	sortOrderOffset := len(*exchanges)
+	for i, exchangeName := range sdk.GetExchangeList() {
 		key := fmt.Sprintf("ccxt-%s", exchangeName)
 		_, tested := testedCcxtExchanges[exchangeName]
 		boundExchangeName := exchangeName
 
-		exchanges[key] = ExchangeContainer{
+		(*exchanges)[key] = ExchangeContainer{
 			SortOrder:    uint16(i + sortOrderOffset),
 			Description:  exchangeName + " is automatically added via ccxt-rest",
 			TradeEnabled: true,
@@ -211,7 +219,7 @@ func init() {
 
 // MakeExchange is a factory method to make an exchange based on a given type
 func MakeExchange(exchangeType string, simMode bool) (api.Exchange, error) {
-	if exchange, ok := exchanges[exchangeType]; ok {
+	if exchange, ok := getExchanges()[exchangeType]; ok {
 		exchangeAPIKey := api.ExchangeAPIKey{Key: "", Secret: ""}
 		x, e := exchange.makeFn(exchangeFactoryData{
 			simMode: simMode,
@@ -228,7 +236,7 @@ func MakeExchange(exchangeType string, simMode bool) (api.Exchange, error) {
 
 // MakeTradingExchange is a factory method to make an exchange based on a given type
 func MakeTradingExchange(exchangeType string, apiKeys []api.ExchangeAPIKey, simMode bool) (api.Exchange, error) {
-	if exchange, ok := exchanges[exchangeType]; ok {
+	if exchange, ok := getExchanges()[exchangeType]; ok {
 		if !exchange.TradeEnabled {
 			return nil, fmt.Errorf("trading is not enabled on this exchange: %s", exchangeType)
 		}
@@ -252,5 +260,5 @@ func MakeTradingExchange(exchangeType string, apiKeys []api.ExchangeAPIKey, simM
 
 // Exchanges returns the list of exchanges
 func Exchanges() map[string]ExchangeContainer {
-	return exchanges
+	return getExchanges()
 }

support/sdk/ccxt.go

@@ -75,27 +75,45 @@ func MakeInitializedCcxtExchange(exchangeName string, apiKey api.ExchangeAPIKey)
 	return c, nil
 }
 
-// ExchangeList contains a list of supported exchanges
-var ExchangeList []string
+// exchangeList contains a list of supported exchanges
+var exchangeList *[]string
 
-func init() {
-	e := networking.JSONRequest(http.DefaultClient, "GET", ccxtBaseURL+pathExchanges, "", map[string]string{}, &ExchangeList, "error")
+// GetExchangeList gets a list of all supported exchanges
+func GetExchangeList() []string {
+	if exchangeList == nil {
+		loadExchangeList()
+	}
+	return *exchangeList
+}
+
+func loadExchangeList() {
+	var output []string
+	e := networking.JSONRequest(http.DefaultClient, "GET", ccxtBaseURL+pathExchanges, "", map[string]string{}, &output, "error")
 	if e != nil {
-		panic(fmt.Errorf("error getting list of supported exchanges by CCXT: %s", e))
+		eMsg1 := strings.Contains(e.Error(), "could not execute http request")
+		eMsg2 := strings.Contains(e.Error(), "http://localhost:3000/exchanges: dial tcp")
+		eMsg3 := strings.Contains(e.Error(), "connection refused")
+		if eMsg1 && eMsg2 && eMsg3 {
+			log.Printf("ccxt-rest is not running on port 3000 so we cannot include those exchanges")
+		} else {
+			panic(fmt.Errorf("error getting list of supported exchanges by CCXT: %s", e))
+		}
 	}
+	exchangeList = &output
 }
 
 func (c *Ccxt) initialize(apiKey api.ExchangeAPIKey) error {
 	// validate that exchange name is in the exchange list
 	exchangeListed := false
-	for _, name := range ExchangeList {
+	el := GetExchangeList()
+	for _, name := range el {
 		if name == c.exchangeName {
 			exchangeListed = true
 			break
 		}
 	}
 	if !exchangeListed {
-		return fmt.Errorf("exchange name '%s' is not in the list of %d exchanges available: %v", c.exchangeName, len(ExchangeList), ExchangeList)
+		return fmt.Errorf("exchange name '%s' is not in the list of %d exchanges available: %v", c.exchangeName, len(el), el)
 	}
 
 	// list all the instances of the exchange