Add crawler skeleton and add handler

internal/crawler.go

@@ -0,0 +1,34 @@
+package internal
+
+import (
+	log "github.com/sirupsen/logrus"
+)
+
+type Crawler interface {
+	Start()
+	Crawl(url string) error
+}
+
+type crawler struct {
+	q chan string
+}
+
+func NewCrawler() (Crawler, error) {
+	return &crawler{q: make(chan string)}, nil
+}
+
+func (c *crawler) loop() {
+	for {
+		url := <-c.q
+		log.Debugf("crawling %s", url)
+	}
+}
+
+func (c *crawler) Crawl(url string) error {
+	c.q <- url
+	return nil
+}
+
+func (c *crawler) Start() {
+	go c.loop()
+}