Add env var support for all the TLS flags.

Signed-off-by: Nick Young <ynick@vmware.com>

cmd/contour/contour.go

@@ -64,9 +64,9 @@ func main() {
 	bootstrap.Flag("admin-port", "Envoy admin interface port").IntVar(&config.AdminPort)
 	bootstrap.Flag("xds-address", "xDS gRPC API address").StringVar(&config.XDSAddress)
 	bootstrap.Flag("xds-port", "xDS gRPC API port").IntVar(&config.XDSGRPCPort)
-	bootstrap.Flag("envoy-cafile", "gRPC CA Filename for Envoy to load").StringVar(&config.GrpcCABundle)
-	bootstrap.Flag("envoy-cert-file", "gRPC Client cert filename for Envoy to load").StringVar(&config.GrpcClientCert)
-	bootstrap.Flag("envoy-key-file", "gRPC Client key filename for Envoy to load").StringVar(&config.GrpcClientKey)
+	bootstrap.Flag("envoy-cafile", "gRPC CA Filename for Envoy to load").Envar("ENVOY_CAFILE").StringVar(&config.GrpcCABundle)
+	bootstrap.Flag("envoy-cert-file", "gRPC Client cert filename for Envoy to load").Envar("ENVOY_CERT_FILE").StringVar(&config.GrpcClientCert)
+	bootstrap.Flag("envoy-key-file", "gRPC Client key filename for Envoy to load").Envar("ENVOY_KEY_FILE").StringVar(&config.GrpcClientKey)
 
 	// Get the running namespace passed via ENV var from the Kubernetes Downward API
 	config.Namespace = getEnv("CONTOUR_NAMESPACE", "heptio-contour")
@@ -97,9 +97,9 @@ func main() {
 	xdsPort := serve.Flag("xds-port", "xDS gRPC API port").Default("8001").Int()
 	statsAddress := serve.Flag("stats-address", "Envoy /stats interface address").Default("0.0.0.0").String()
 	statsPort := serve.Flag("stats-port", "Envoy /stats interface port").Default("8002").Int()
-	caFile := serve.Flag("contour-cafile", "CA bundle file name for serving gRPC with TLS").String()
-	contourCert := serve.Flag("contour-cert-file", "Contour certificate file name for serving gRPC over TLS").String()
-	contourKey := serve.Flag("contour-key-file", "Contour key file name for serving gRPC over TLS").String()
+	caFile := serve.Flag("contour-cafile", "CA bundle file name for serving gRPC with TLS").Envar("CONTOUR_CAFILE").String()
+	contourCert := serve.Flag("contour-cert-file", "Contour certificate file name for serving gRPC over TLS").Envar("CONTOUR_CERT_FILE").String()
+	contourKey := serve.Flag("contour-key-file", "Contour key file name for serving gRPC over TLS").Envar("CONTOUR_KEY_FILE").String()
 
 	ch := contour.CacheHandler{
 		FieldLogger: log.WithField("context", "CacheHandler"),