add cluster alert links (#16426)

api/types/cluster_alert.go

@@ -17,6 +17,7 @@ limitations under the License.
 package types
 
 import (
+	"net/url"
 	"regexp"
 	"sort"
 	"time"
@@ -28,6 +29,8 @@ import (
 // matchStrictLabel is a fairly conservative allowed charset for labels.
 var matchStrictLabel = regexp.MustCompile(`^[a-z0-9\.\-\/]+$`).MatchString
 
+const validLinkDestination = "goteleport.com"
+
 type alertOptions struct {
 	labels   map[string]string
 	severity AlertSeverity
@@ -112,7 +115,7 @@ func (c *ClusterAlert) setDefaults() {
 	}
 }
 
-// CheckAndSetDefaults verfies required fields.
+// CheckAndSetDefaults verifies required fields.
 func (c *ClusterAlert) CheckAndSetDefaults() error {
 	c.setDefaults()
 	if c.Version != V1 {
@@ -135,9 +138,20 @@ func (c *ClusterAlert) CheckAndSetDefaults() error {
 		if !matchStrictLabel(key) {
 			return trace.BadParameter("invalid alert label key: %q", key)
 		}
-		if !matchStrictLabel(val) {
+		// for links, we relax the conditions on label values
+		if key != AlertLink && !matchStrictLabel(val) {
 			return trace.BadParameter("invalid alert label value: %q", val)
 		}
+
+		if key == AlertLink {
+			u, err := url.Parse(val)
+			if err != nil {
+				return trace.BadParameter("invalid alert: label link %q is not a valid URL", val)
+			}
+			if u.Hostname() != validLinkDestination {
+				return trace.BadParameter("invalid alert: label link not allowed %q", val)
+			}
+		}
 	}
 	return nil
 }

api/types/cluster_alert_test.go

@@ -82,3 +82,35 @@ func TestAlertSorting(t *testing.T) {
 		require.Equal(t, fmt.Sprintf("%d", i), a.Metadata.Labels["p"])
 	}
 }
+
+// TestCheckAndSetDefaults verifies that only valid URLs are set on the link label.
+func TestCheckAndSetDefaultsWithLink(t *testing.T) {
+	tests := []struct {
+		link   string
+		assert require.ErrorAssertionFunc
+	}{
+		{
+			link:   "https://goteleport.com/docs",
+			assert: require.NoError,
+		},
+		{
+			link:   "h{t}tps://goteleport.com/docs",
+			assert: require.Error,
+		},
+		{
+			link:   "https://google.com",
+			assert: require.Error,
+		},
+	}
+
+	for i, tt := range tests {
+		t.Run(tt.link, func(t *testing.T) {
+			_, err := NewClusterAlert(
+				fmt.Sprintf("name-%d", i),
+				fmt.Sprintf("message-%d", i),
+				WithAlertLabel(AlertLink, tt.link),
+			)
+			tt.assert(t, err)
+		})
+	}
+}

api/types/constants.go

@@ -455,6 +455,9 @@ const (
 
 	// AlertPermitAll is an internal label that indicates that an alert is suitable for display to all users.
 	AlertPermitAll = "teleport.internal/alert-permit-all"
+
+	// AlertLink is an internal label that indicates that an alert is a link.
+	AlertLink = "teleport.internal/link"
 )
 
 // RequestableResourceKinds lists all Teleport resource kinds users can request access to.