httptransport: add "robots.txt" endpoint

Signed-off-by: Hank Donnay <hdonnay@redhat.com>

httptransport/robotshandler.go

@@ -0,0 +1,26 @@
+package httptransport
+
+import (
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/quay/clair/v4/cmd"
+)
+
+var startup = time.Now()
+
+const robotstxt = "User-agent: *\nDisallow: /\n"
+
+// RobotsHandler provides a "robots.txt" endpoint.
+var robotsHandler http.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	h := w.Header()
+	h.Set("X-Content-Type-Options", "nosniff")
+	h.Set("Content-Type", "text/plain; charset=utf-8")
+	h.Set("Cache-Control", "no-store")
+	d := cmd.CommitDate
+	if d.IsZero() {
+		d = startup
+	}
+	http.ServeContent(w, r, "robots.txt", d, strings.NewReader(robotstxt))
+})

httptransport/robotshandler_test.go

@@ -0,0 +1,26 @@
+package httptransport
+
+import (
+	"bytes"
+	"net/http"
+	"net/http/httptest"
+	"net/http/httputil"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestRobotsTXT(t *testing.T) {
+	r := httptest.NewRequest(http.MethodGet, "/robots.txt", nil)
+	w := httptest.NewRecorder()
+	robotsHandler.ServeHTTP(w, r)
+	res, err := httputil.DumpResponse(w.Result(), false)
+	if err != nil {
+		t.Error(err)
+	}
+	t.Logf("response:\n%s", string(res))
+
+	if got, want := w.Body.Bytes(), []byte(robotstxt); !bytes.Equal(got, want) {
+		t.Error(cmp.Diff(string(got), string(want)))
+	}
+}