Add external drivers to the code base

drivers/driver_main.go

@@ -0,0 +1,38 @@
+package drivers
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+)
+
+// DriverMain helps dry up the implementation of main.go for drivers
+func DriverMain(driver Interface) {
+	b, err := ioutil.ReadAll(os.Stdin)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "failed to read from stdin")
+		os.Exit(1)
+	}
+
+	var config Config
+	err = json.Unmarshal(b, &config)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to parse json from stdin: %v\n%s\n", err, b)
+		os.Exit(1)
+	}
+
+	dinfo, err := driver.Assemble(config)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
+	b, err = json.Marshal(dinfo)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "failed to marshal json:", err)
+		os.Exit(1)
+	}
+
+	os.Stdout.Write(b)
+}