Feature: add experimental provider

adapters/provider/vehicle.go

@@ -0,0 +1,109 @@
+package provider
+
+import (
+	"context"
+	"io/ioutil"
+	"net/http"
+	"time"
+)
+
+// Vehicle Type
+const (
+	File VehicleType = iota
+	HTTP
+	Compatible
+)
+
+// VehicleType defined
+type VehicleType int
+
+func (v VehicleType) String() string {
+	switch v {
+	case File:
+		return "File"
+	case HTTP:
+		return "HTTP"
+	case Compatible:
+		return "Compatible"
+	default:
+		return "Unknown"
+	}
+}
+
+type Vehicle interface {
+	Read() ([]byte, error)
+	Path() string
+	Type() VehicleType
+}
+
+type FileVehicle struct {
+	path string
+}
+
+func (f *FileVehicle) Type() VehicleType {
+	return File
+}
+
+func (f *FileVehicle) Path() string {
+	return f.path
+}
+
+func (f *FileVehicle) Read() ([]byte, error) {
+	return ioutil.ReadFile(f.path)
+}
+
+func NewFileVehicle(path string) *FileVehicle {
+	return &FileVehicle{path: path}
+}
+
+type HTTPVehicle struct {
+	url  string
+	path string
+}
+
+func (h *HTTPVehicle) Type() VehicleType {
+	return HTTP
+}
+
+func (h *HTTPVehicle) Path() string {
+	return h.path
+}
+
+func (h *HTTPVehicle) Read() ([]byte, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*20)
+	defer cancel()
+
+	req, err := http.NewRequest(http.MethodGet, h.url, nil)
+	if err != nil {
+		return nil, err
+	}
+	req = req.WithContext(ctx)
+
+	transport := &http.Transport{
+		// from http.DefaultTransport
+		MaxIdleConns:          100,
+		IdleConnTimeout:       90 * time.Second,
+		TLSHandshakeTimeout:   10 * time.Second,
+		ExpectContinueTimeout: 1 * time.Second,
+	}
+
+	client := http.Client{Transport: transport}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	buf, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := ioutil.WriteFile(h.path, buf, fileMode); err != nil {
+		return nil, err
+	}
+
+	return buf, nil
+}
+
+func NewHTTPVehicle(url string, path string) *HTTPVehicle {
+	return &HTTPVehicle{url, path}
+}