added health_follow_redirect in active health checks

modules/caddyhttp/reverseproxy/caddyfile.go

@@ -450,6 +450,12 @@ func (h *Handler) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 			}
 			h.HealthChecks.Active.ExpectBody = d.Val()
 
+		case "health_follow_redirects":
+			if d.NextArg() {
+				return d.ArgErr()
+			}
+            h.HealthChecks.Active.HealthFollowRedirects = true
+
 		case "health_passes":
 			if !d.NextArg() {
 				return d.ArgErr()
@@ -644,6 +650,7 @@ func (h *Handler) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 				h.TrustedProxies = append(h.TrustedProxies, d.Val())
 			}
 
+
 		case "header_up":
 			var err error
 

modules/caddyhttp/reverseproxy/healthchecks.go

@@ -83,6 +83,9 @@ type ActiveHealthChecks struct {
 	// HTTP headers to set on health check requests.
 	Headers http.Header `json:"headers,omitempty"`
 
+	// boolean to follow redirects in health checks disabled by default
+	HealthFollowRedirects bool `json:"health_follow_redirects,omitempty"`
+
 	// How frequently to perform active health checks (default 30s).
 	Interval caddy.Duration `json:"interval,omitempty"`
 
@@ -155,7 +158,12 @@ func (a *ActiveHealthChecks) Provision(ctx caddy.Context, h *Handler) error {
 		Timeout:   timeout,
 		Transport: h.Transport,
         CheckRedirect: func(req *http.Request, via []*http.Request) error {
-            return errors.New("Cannot redirect")
+            if !a.HealthFollowRedirects {
+                return errors.New(
+                    "Redirects are disabled in health check, set health_follow_redirects flag in config to avoid this error")
+            } else {
+                return nil
+            }
         },
 	}