Merge pull request #226 from DopplerHQ/dns

Use custom DNS resolver

pkg/cmd/root.go

@@ -30,6 +30,8 @@ import (
 	"gopkg.in/gookit/color.v1"
 )
 
+var printConfig = false
+
 var rootCmd = &cobra.Command{
 	Use:   "doppler",
 	Short: "The official Doppler CLI",
@@ -44,7 +46,6 @@ var rootCmd = &cobra.Command{
 		}
 
 		// this output does not honor --silent
-		printConfig := utils.GetBoolFlagIfChanged(cmd, "print-config", false)
 		if printConfig {
 			fmt.Println("Active configuration")
 			printer.ScopedConfigSource(configuration.LocalConfig(cmd), false, true, true)
@@ -119,14 +120,20 @@ func loadFlags(cmd *cobra.Command) {
 		utils.HandleError(err, fmt.Sprintf("Invalid scope: %s", scope))
 	}
 
+	configuration.CanReadEnv = !utils.GetBoolFlag(cmd, "no-read-env")
 	configuration.UserConfigFile = utils.GetPathFlagIfChanged(cmd, "configuration", configuration.UserConfigFile)
-	http.TimeoutDuration = utils.GetDurationFlagIfChanged(cmd, "timeout", http.TimeoutDuration)
-	http.UseTimeout = !utils.GetBoolFlagIfChanged(cmd, "no-timeout", !http.UseTimeout)
-	utils.Debug = utils.GetBoolFlagIfChanged(cmd, "debug", utils.Debug)
-	utils.Silent = utils.GetBoolFlagIfChanged(cmd, "silent", utils.Silent)
+	http.UseTimeout = !utils.GetBoolFlag(cmd, "no-timeout")
+
+	// DNS resolver
+	http.UseCustomDNSResolver = !utils.GetBoolFlag(cmd, "no-dns-resolver")
+	if configuration.CanReadEnv && os.Getenv("DOPPLER_DISABLE_DNS_RESOLVER") == "true" {
+		http.UseCustomDNSResolver = false
+	}
+
 	// no-file is used by the 'secrets download' command to output secrets to stdout
 	utils.Silent = utils.GetBoolFlagIfChanged(cmd, "no-file", utils.Silent)
-	utils.OutputJSON = utils.GetBoolFlagIfChanged(cmd, "json", utils.OutputJSON)
+
+	// version check
 	version.PerformVersionCheck = !utils.GetBoolFlagIfChanged(cmd, "no-check-version", !version.PerformVersionCheck)
 }
 
@@ -167,13 +174,18 @@ func init() {
 	rootCmd.PersistentFlags().Bool("no-check-version", !version.PerformVersionCheck, "disable checking for Doppler CLI updates")
 	rootCmd.PersistentFlags().Bool("no-verify-tls", false, "do not verify the validity of TLS certificates on HTTP requests (not recommended)")
 	rootCmd.PersistentFlags().Bool("no-timeout", !http.UseTimeout, "disable http timeout")
-	rootCmd.PersistentFlags().Duration("timeout", http.TimeoutDuration, "max http request duration")
+	rootCmd.PersistentFlags().DurationVar(&http.TimeoutDuration, "timeout", http.TimeoutDuration, "max http request duration")
+	// DNS resolver
+	rootCmd.PersistentFlags().Bool("no-dns-resolver", !http.UseCustomDNSResolver, "use the OS's default DNS resolver")
+	rootCmd.PersistentFlags().StringVar(&http.DNSResolverAddress, "dns-resolver-address", http.DNSResolverAddress, "address to use for DNS resolution")
+	rootCmd.PersistentFlags().StringVar(&http.DNSResolverProto, "dns-resolver-proto", http.DNSResolverProto, "protocol to use for DNS resolution")
+	rootCmd.PersistentFlags().DurationVar(&http.DNSResolverTimeout, "dns-resolver-timeout", http.DNSResolverTimeout, "max dns lookup duration")
 
 	rootCmd.PersistentFlags().Bool("no-read-env", false, "do not read config from the environment")
 	rootCmd.PersistentFlags().String("scope", configuration.Scope, "the directory to scope your config to")
 	rootCmd.PersistentFlags().String("configuration", configuration.UserConfigFile, "config file")
-	rootCmd.PersistentFlags().Bool("json", utils.OutputJSON, "output json")
-	rootCmd.PersistentFlags().Bool("debug", utils.Debug, "output additional information")
-	rootCmd.PersistentFlags().Bool("print-config", false, "output active configuration")
-	rootCmd.PersistentFlags().Bool("silent", utils.Silent, "disable output of info messages")
+	rootCmd.PersistentFlags().BoolVar(&utils.OutputJSON, "json", utils.OutputJSON, "output json")
+	rootCmd.PersistentFlags().BoolVar(&utils.Debug, "debug", utils.Debug, "output additional information")
+	rootCmd.PersistentFlags().BoolVar(&printConfig, "print-config", printConfig, "output active configuration")
+	rootCmd.PersistentFlags().BoolVar(&utils.Silent, "silent", utils.Silent, "disable output of info messages")
 }

pkg/configuration/config.go

@@ -44,6 +44,9 @@ var UserConfigFile string
 // Scope to use for config file
 var Scope = "."
 
+// CanReadEnv whether configuration can be read from the environment
+var CanReadEnv = true
+
 var configFileName = ".doppler.yaml"
 var configContents models.ConfigFile
 
@@ -169,7 +172,7 @@ func LocalConfig(cmd *cobra.Command) models.ScopedOptions {
 	localConfig := Get(Scope)
 
 	// environment variables
-	if !utils.GetBoolFlag(cmd, "no-read-env") {
+	if CanReadEnv {
 		pairs := models.EnvPairs(&localConfig)
 		envVars := []string{}
 		for envVar := range pairs {

pkg/http/http.go

@@ -17,6 +17,7 @@ package http
 
 import (
 	"bytes"
+	"context"
 	"crypto/tls"
 	"encoding/json"
 	"errors"
@@ -42,6 +43,12 @@ type errorResponse struct {
 	Success  bool
 }
 
+// DNS resolver
+var UseCustomDNSResolver = false
+var DNSResolverAddress = "1.1.1.1:53"
+var DNSResolverProto = "udp"
+var DNSResolverTimeout = time.Duration(5) * time.Second
+
 // GetRequest perform HTTP GET
 func GetRequest(host string, verifyTLS bool, headers map[string]string, uri string, params []queryParam) (int, http.Header, []byte, error) {
 	url := fmt.Sprintf("%s%s", host, uri)
@@ -128,19 +135,42 @@ func performRequest(req *http.Request, verifyTLS bool, params []queryParam) (int
 		client.Timeout = TimeoutDuration
 	}
 
+	// set TLS config
 	tlsConfig := &tls.Config{
 		MinVersion: tls.VersionTLS12,
 	}
-	// set TLS config
 	// #nosec G402
 	if !verifyTLS {
 		tlsConfig.InsecureSkipVerify = true
 	}
+
+	// use custom DNS resolver
+	dialer := &net.Dialer{}
+	if UseCustomDNSResolver {
+		utils.LogDebug(fmt.Sprintf("Using custom DNS resolver %s", DNSResolverAddress))
+
+		dialer = &net.Dialer{
+			Resolver: &net.Resolver{
+				PreferGo: true,
+				Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
+					d := net.Dialer{
+						Timeout: DNSResolverTimeout,
+					}
+					return d.DialContext(ctx, DNSResolverProto, DNSResolverAddress)
+				},
+			},
+		}
+	}
+	dialContext := func(ctx context.Context, network, addr string) (net.Conn, error) {
+		return dialer.DialContext(ctx, network, addr)
+	}
+
 	client.Transport = &http.Transport{
 		// disable keep alives to prevent multiple CLI instances from exhausting the
 		// OS's available network sockets. this adds a negligible performance penalty
 		DisableKeepAlives: true,
 		TLSClientConfig:   tlsConfig,
+		DialContext:       dialContext,
 	}
 
 	startTime := time.Now()