reverseproxy: Correct alternate port for active health checks (#3693)

* reverseproxy: construct active health-check transport from scratch (Fixes #3691)

* reverseproxy: do upstream health-check on the correct alternative port

* reverseproxy: add integration test for health-check on alternative port

* reverseproxy: put back the custom transport for health-check http client

* reverseproxy: cleanup health-check integration test

* reverseproxy: fix health-check of unix socket upstreams

* reverseproxy: skip unix socket tests on Windows

* tabs > spaces

Co-authored-by: Francis Lavoie <lavofr@gmail.com>

* make the linter (and @francislavoie) happy

Co-authored-by: Francis Lavoie <lavofr@gmail.com>

* One more lint fix

Co-authored-by: Francis Lavoie <lavofr@gmail.com>

Co-authored-by: Francis Lavoie <lavofr@gmail.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/modules/caddyhttp/reverseproxy/reverseproxy.go b/modules/caddyhttp/reverseproxy/reverseproxy.go
index 910fbfc..138a3fc 100644
--- a/modules/caddyhttp/reverseproxy/reverseproxy.go
+++ b/modules/caddyhttp/reverseproxy/reverseproxy.go
@@ -208,9 +208,13 @@ func (h *Handler) Provision(ctx caddy.Context) error {
 		if err != nil {
 			return err
 		}
+
 		if addr.PortRangeSize() != 1 {
 			return fmt.Errorf("multiple addresses (upstream must map to only one address): %v", addr)
 		}
+
+		upstream.networkAddress = addr
+
 		// create or get the host representation for this upstream
 		var host Host = new(upstreamHost)
 		existingHost, loaded := hosts.LoadOrStore(upstream.String(), host)
@@ -267,6 +271,16 @@ func (h *Handler) Provision(ctx caddy.Context) error {
 				Transport: h.Transport,
 			}
 
+			for _, upstream := range h.Upstreams {
+				// if there's an alternative port for health-check provided in the config,
+				// then use it, otherwise use the port of upstream.
+				if h.HealthChecks.Active.Port != 0 {
+					upstream.activeHealthCheckPort = h.HealthChecks.Active.Port
+				} else {
+					upstream.activeHealthCheckPort = int(upstream.networkAddress.StartPort)
+				}
+			}
+
 			if h.HealthChecks.Active.Interval == 0 {
 				h.HealthChecks.Active.Interval = caddy.Duration(30 * time.Second)
 			}