add /.export-stats endpoint to dump stats table

db.go

@@ -16,6 +16,7 @@ import (
 	"time"
 
 	_ "modernc.org/sqlite"
+	"tailscale.com/tstime"
 )
 
 // Link is the structure stored for each go short link.
@@ -42,6 +43,8 @@ func linkID(short string) string {
 type SQLiteDB struct {
 	db *sql.DB
 	mu sync.RWMutex
+
+	clock tstime.Clock // allow overriding time for tests
 }
 
 //go:embed schema.sql
@@ -64,6 +67,11 @@ func NewSQLiteDB(f string) (*SQLiteDB, error) {
 	return &SQLiteDB{db: db}, nil
 }
 
+// Now returns the current time.
+func (s *SQLiteDB) Now() time.Time {
+	return tstime.DefaultClock{Clock: s.clock}.Now()
+}
+
 // LoadAll returns all stored Links.
 //
 // The caller owns the returned values.
@@ -195,7 +203,7 @@ func (s *SQLiteDB) SaveStats(stats ClickStats) error {
 	if err != nil {
 		return err
 	}
-	now := time.Now().Unix()
+	now := s.Now().Unix()
 	for short, clicks := range stats {
 		_, err := tx.Exec("INSERT INTO Stats (ID, Created, Clicks) VALUES (?, ?, ?)", linkID(short), now, clicks)
 		if err != nil {

flake.nix

@@ -39,7 +39,7 @@
               "-X tailscale.com/version.longStamp=${tsVersion}"
               "-X tailscale.com/version.shortStamp=${tsVersion}"
             ];
-          vendorHash = "sha256-k3BxPRTgoJM0oCixDVA2k44ztdAUZO4IcO2/QB19HvU="; # SHA based on vendoring go.mod
+          vendorHash = "sha256-tF3TuIWr5x4inGrykXAjXBQATpDdpTX8HDYmEeukTEc="; # SHA based on vendoring go.mod
         };
       });
 

golink.go

@@ -421,6 +421,7 @@ func serveHandler() http.Handler {
 	mux := http.NewServeMux()
 	mux.HandleFunc("/.detail/", serveDetail)
 	mux.HandleFunc("/.export", serveExport)
+	mux.HandleFunc("/.export-stats", serveExportStats)
 	mux.HandleFunc("/.help", serveHelp)
 	mux.HandleFunc("/.opensearch", serveOpenSearch)
 	mux.HandleFunc("/.all", serveAll)
@@ -990,6 +991,42 @@ func serveExport(w http.ResponseWriter, _ *http.Request) {
 	}
 }
 
+// serveExportStats prints a snapshot of the stats database table.
+//
+// Stats are printed in CSV format with three columns: link ID, UNIX timestamp, and click count.
+// Each stat line represents the number of clicks in the previous minute.
+func serveExportStats(w http.ResponseWriter, _ *http.Request) {
+	if err := flushStats(); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	rows, err := db.db.Query("SELECT ID, Created, Clicks FROM Stats ORDER BY Created, ID")
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	defer func() {
+		rows.Close()
+		if err := rows.Err(); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+		}
+	}()
+
+	for rows.Next() {
+		var id string
+		var created int64
+		var clicks int
+		err := rows.Scan(&id, &created, &clicks)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		// id is not permitted to contain commas, so no need to worry about CSV quoting
+		fmt.Fprintf(w, "%s,%d,%d\n", id, created, clicks)
+	}
+}
+
 func restoreLastSnapshot() error {
 	bs := bufio.NewScanner(bytes.NewReader(LastSnapshot))
 	var restored int

golink_test.go

@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"golang.org/x/net/xsrftoken"
+	"tailscale.com/tstest"
 	"tailscale.com/types/ptr"
 	"tailscale.com/util/must"
 )
@@ -358,6 +359,67 @@ func TestServeDelete(t *testing.T) {
 	}
 }
 
+func TestServeExport(t *testing.T) {
+	clock := tstest.NewClock(tstest.ClockOpts{
+		Start: time.Date(2022, 06, 02, 1, 2, 3, 4, time.UTC),
+	})
+
+	var err error
+	db, err = NewSQLiteDB(":memory:")
+	db.clock = clock
+	if err != nil {
+		t.Fatal(err)
+	}
+	db.Save(&Link{Short: "a", Owner: "a@example.com"})
+	db.Save(&Link{Short: "foo", Owner: "foo@example.com"})
+	db.Save(&Link{Short: "link-owned-by-tagged-devices", Long: "/before", Owner: "tagged-devices"})
+
+	click := func(id string) {
+		r := httptest.NewRequest("GET", "/"+id, nil)
+		w := httptest.NewRecorder()
+		serveHandler().ServeHTTP(w, r)
+	}
+	initStats()
+	click("a")
+	click("foo")
+	click("foo")
+	flushStats()
+	clock.Advance(3 * time.Minute)
+	click("a")
+
+	// export links
+	r := httptest.NewRequest("GET", "/.export", nil)
+	w := httptest.NewRecorder()
+	serveHandler().ServeHTTP(w, r)
+
+	if want := http.StatusOK; w.Code != want {
+		t.Errorf("serveExport = %d; want %d", w.Code, want)
+	}
+	wantOutput := `{"Short":"a","Long":"","Created":"0001-01-01T00:00:00Z","LastEdit":"0001-01-01T00:00:00Z","Owner":"a@example.com"}
+{"Short":"foo","Long":"","Created":"0001-01-01T00:00:00Z","LastEdit":"0001-01-01T00:00:00Z","Owner":"foo@example.com"}
+{"Short":"link-owned-by-tagged-devices","Long":"/before","Created":"0001-01-01T00:00:00Z","LastEdit":"0001-01-01T00:00:00Z","Owner":"tagged-devices"}
+`
+	if got := w.Body.String(); got != wantOutput {
+		t.Errorf("serveExport = %v; want %v", got, wantOutput)
+	}
+
+	// export links stats
+	r = httptest.NewRequest("GET", "/.export-stats", nil)
+	w = httptest.NewRecorder()
+	serveHandler().ServeHTTP(w, r)
+
+	if want := http.StatusOK; w.Code != want {
+		t.Errorf("serveExportStats = %d; want %d", w.Code, want)
+	}
+	wantOutput = `a,1654131723,1
+foo,1654131723,2
+a,1654131903,1
+`
+	if got := w.Body.String(); got != wantOutput {
+		t.Errorf("serveExportStats = %v; want %v", got, wantOutput)
+	}
+}
+
 func TestReadOnlyMode(t *testing.T) {
 	var err error
 	db, err = NewSQLiteDB(":memory:")