Improve https get diagnostics, add verbose option

* Implement a logging client and activate it using verbose parameter or option
   in checker and aggregator.

Co-authored-by: Sascha L. Teichmann <sascha.teichmann@intevation.de>

util/client.go

@@ -11,6 +11,7 @@ package util
 import (
 	"context"
 	"io"
+	"log"
 	"net/http"
 	"net/url"
 
@@ -26,12 +27,47 @@ type Client interface {
 	PostForm(url string, data url.Values) (*http.Response, error)
 }
 
+// LoggingClient is a client that logs called URLs.
+type LoggingClient struct {
+	Client
+}
+
 // LimitingClient is a Client implementing rate throttling.
 type LimitingClient struct {
 	Client
 	Limiter *rate.Limiter
 }
 
+// Do implements the respective method of the Client interface.
+func (lc *LoggingClient) Do(req *http.Request) (*http.Response, error) {
+	log.Printf("[DO]: %s\n", req.URL.String())
+	return lc.Do(req)
+}
+
+// Get implements the respective method of the Client interface.
+func (lc *LoggingClient) Get(url string) (*http.Response, error) {
+	log.Printf("[GET]: %s\n", url)
+	return lc.Client.Get(url)
+}
+
+// Head implements the respective method of the Client interface.
+func (lc *LoggingClient) Head(url string) (*http.Response, error) {
+	log.Printf("[HEAD]: %s\n", url)
+	return lc.Head(url)
+}
+
+// Post implements the respective method of the Client interface.
+func (lc *LoggingClient) Post(url, contentType string, body io.Reader) (*http.Response, error) {
+	log.Printf("[POST]: %s\n", url)
+	return lc.Post(url, contentType, body)
+}
+
+// PostForm implements the respective method of the Client interface.
+func (lc *LoggingClient) PostForm(url string, data url.Values) (*http.Response, error) {
+	log.Printf("[POST FORM]: %s\n", url)
+	return lc.PostForm(url, data)
+}
+
 // Do implements the respective method of the Client interface.
 func (lc *LimitingClient) Do(req *http.Request) (*http.Response, error) {
 	lc.Limiter.Wait(context.Background())