Add HTTP API

Add `-api` mode to start the HTTP API with the following routes:
- /health
- /shops
- /shops/:id
- /products
- /products/:id

Signed-off-by: Julien Riou <julien@riou.xyz>

config.go

@@ -10,6 +10,7 @@ import (
 type Config struct {
 	TwitterConfig  `json:"twitter"`
 	TelegramConfig `json:"telegram"`
+	ApiConfig      `json:"api"`
 	URLs           []string `json:"urls"`
 	IncludeRegex   string   `json:"include_regex"`
 	ExcludeRegex   string   `json:"exclude_regex"`
@@ -32,6 +33,13 @@ type TelegramConfig struct {
 	ChannelName string `json:"channel_name"`
 }
 
+// ApiConfig to store HTTP API configuration
+type ApiConfig struct {
+	Address  string `json:"address"`
+	Certfile string `json:"cert_file"`
+	Keyfile  string `json:"key_file"`
+}
+
 // NewConfig creates a Config struct
 func NewConfig() *Config {
 	return &Config{}