reverseproxy: Implement retry count, alternative to try_duration (#4756)

* reverseproxy: Implement retry count, alternative to try_duration

* Add Caddyfile support for `retry_match`

* Refactor to deduplicate matcher parsing logic

* Fix lint

1 files changed, 25 insertions, 0 deletions

diff --git a/modules/caddyhttp/reverseproxy/caddyfile.go b/modules/caddyhttp/reverseproxy/caddyfile.go
index 4fa4be0..a5321d1 100644
--- a/modules/caddyhttp/reverseproxy/caddyfile.go
+++ b/modules/caddyhttp/reverseproxy/caddyfile.go
@@ -59,8 +59,10 @@ func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error)
 //
 //         # load balancing
 //         lb_policy <name> [<options...>]
+//         lb_retries <retries>
 //         lb_try_duration <duration>
 //         lb_try_interval <interval>
+//         lb_retry_match <request-matcher>
 //
 //         # active health checking
 //         health_uri      <uri>
@@ -247,6 +249,19 @@ func (h *Handler) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 				}
 				h.LoadBalancing.SelectionPolicyRaw = caddyconfig.JSONModuleObject(sel, "policy", name, nil)
 
+			case "lb_retries":
+				if !d.NextArg() {
+					return d.ArgErr()
+				}
+				tries, err := strconv.Atoi(d.Val())
+				if err != nil {
+					return d.Errf("bad lb_retries number '%s': %v", d.Val(), err)
+				}
+				if h.LoadBalancing == nil {
+					h.LoadBalancing = new(LoadBalancing)
+				}
+				h.LoadBalancing.Retries = tries
+
 			case "lb_try_duration":
 				if !d.NextArg() {
 					return d.ArgErr()
@@ -273,6 +288,16 @@ func (h *Handler) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 				}
 				h.LoadBalancing.TryInterval = caddy.Duration(dur)
 
+			case "lb_retry_match":
+				matcherSet, err := caddyhttp.ParseCaddyfileNestedMatcherSet(d)
+				if err != nil {
+					return d.Errf("failed to parse lb_retry_match: %v", err)
+				}
+				if h.LoadBalancing == nil {
+					h.LoadBalancing = new(LoadBalancing)
+				}
+				h.LoadBalancing.RetryMatchRaw = append(h.LoadBalancing.RetryMatchRaw, matcherSet)
+
 			case "health_uri":
 				if !d.NextArg() {
 					return d.ArgErr()