Can not flush cache

[sylloger]

caddy version: 1.11.2

$ curl -v -X PURGE http://localhost:2019/souin-api/souin/flush
* Host localhost:2019 was resolved.
* IPv6: ::1
* IPv4: 127.0.0.1
*   Trying [::1]:2019...
* Connected to localhost (::1) port 2019
* using HTTP/1.x
> PURGE /souin-api/souin/flush HTTP/1.1
> Host: localhost:2019
> User-Agent: curl/8.14.1
> Accept: */*
> 
* Request completely sent off
* Empty reply from server
* shutting down connection #0
curl: (52) Empty reply from server

log

{"level":"info","ts":1773995888.740839,"logger":"admin.api","msg":"received request","method":"PURGE","host":"localhost:2019","uri":"/souin-api/souin/flush","remote_ip":"10.88.0.112","remote_port":"54338","headers":{"Accept":["*/*"],"User-Agent":["curl/8.14.1"]}}
{"level":"info","ts":1773995888.7425144,"msg":"http: panic serving 10.88.0.112:54338: runtime error: invalid memory address or nil pointer dereference\ngoroutine 2663 [running]:\nnet/http.(*conn).serve.func1()\n\tnet/http/server.go:1907 +0xbd\npanic({0x1c7bd00?, 0x37542c0?})\n\truntime/panic.go:860 +0x13a\ngithub.com/darkweak/souin/pkg/api.(*SouinAPI).HandleRequest(0x2514e81b5020, {0x23581f0, 0x2514e9083110}, 0x2514e8130140)\n\tgithub.com/darkweak/souin@v1.7.7/pkg/api/souin.go:316 +0x931\ngithub.com/caddyserver/cache-handler.(*adminAPI).handleAPIEndpoints(0x2514e8643050?, {0x23581f0, 0x2514e9083110}, 0x2514e8130140)\n\tgithub.com/caddyserver/cache-handler@v0.16.0/admin.go:41 +0xf2\ngithub.com/caddyserver/caddy/v2.AdminHandlerFunc.ServeHTTP(0x425234?, {0x23581f0?, 0x2514e9083110?}, 0x2514e925aab0?)\n\tgithub.com/caddyserver/caddy/v2@v2.11.2/admin.go:1360 +0x29\ngithub.com/caddyserver/caddy/v2.(*AdminConfig).newAdminHandler.(*AdminConfig).newAdminHandler.func2.func6({0x23581f0, 0x2514e9083110}, 0x2514e8130140)\n\tgithub.com/caddyserver/caddy/v2@v2.11.2/admin.go:248 +0x7b\nnet/http.HandlerFunc.ServeHTTP(0x2358580?, {0x23581f0?, 0x2514e9083110?}, 0x2514e860b750?)\n\tnet/http/server.go:2286 +0x29\ngithub.com/caddyserver/caddy/v2.(*AdminConfig).newAdminHandler.func1.instrumentHandlerCounter.1({0x2358580?, 0x2514e82fe5a0?}, 0x2514e8130140)\n\tgithub.com/caddyserver/caddy/v2@v2.11.2/metrics.go:56 +0x6f\nnet/http.HandlerFunc.ServeHTTP(0x2514e927e3c0?, {0x2358580?, 0x2514e82fe5a0?}, 0x74c47f?)\n\tnet/http/server.go:2286 +0x29\nnet/http.(*ServeMux).ServeHTTP(0x2514e8640f90?, {0x2358580, 0x2514e82fe5a0}, 0x2514e8130140)\n\tnet/http/server.go:2828 +0x1c7\ngithub.com/caddyserver/caddy/v2.adminHandler.serveHTTP({0x2514e927e3c0, 0x0, 0x0, {0x2514e7e86528, 0x1, 0x1}, 0x0}, {0x2358580, 0x2514e82fe5a0}, 0x2514e8130140)\n\tgithub.com/caddyserver/caddy/v2@v2.11.2/admin.go:891 +0x793\ngithub.com/caddyserver/caddy/v2.adminHandler.ServeHTTP({0x2514e927e3c0, 0x0, 0x0, {0x2514e7e86528, 0x1, 0x1}, 0x0}, {0x2358580, 0x2514e82fe5a0}, 0x2514e8130140)\n\tgithub.com/caddyserver/caddy/v2@v2.11.2/admin.go:816 +0x7a5\nnet/http.serverHandler.ServeHTTP({0x2514e829d180?}, {0x2358580?, 0x2514e82fe5a0?}, 0x1?)\n\tnet/http/server.go:3311 +0x8e\nnet/http.(*conn).serve(0x2514e925aa20, {0x235da70, 0x2514e85e1380})\n\tnet/http/server.go:2073 +0x650\ncreated by net/http.(*Server).Serve in goroutine 2372\n\tnet/http/server.go:3464 +0x485"}

Caddyfile

{
	debug
	order cache before rewrite

	cache {
		api {
			souin
		}
	}
}

example.com {
    @cacheable {
        not path /
    }
    handle @cacheable {
        cache {
            ttl 120s
        }
    }

    file_server
}

[kasparsd]

I dug into this locally and was able to reproduce, patch, and verify it.

Environment:

• FrankenPHP/Caddy: v2.11.2
• cache-handler: v0.16.0
• Souin: v1.7.8

Repro:

• Warm a tagged page so it returns Surrogate-Key: post:2
• Confirm it is cached (Cache-Status: Souin; hit)
• Call:
  PURGE http://localhost:2019/souin-api/souin
  Surrogate-Key: post:2

Before patch:

• GET /souin-api/souin works
• PURGE /souin-api/souin panics in github.com/darkweak/souin/pkg/api/souin.go:330
• nil deref is on s.surrogateStorage.Purge(r.Header)

Root cause:

• this is on the admin API path, not the frontend route path
• admin.go builds the Souin handler map before the live surrogate storage exists
• the live surrogate storage is created later by the HTTP cache middleware in httpcache.go
• so the admin handler map ends up holding a nil surrogateStorage, while normal frontend caching still works

In other words: initialization order is wrong for the admin purge API.

I got it working with a small refactor:

1. move runtime surrogate lookup behind SouinApp
2. let admin handlers build against the live surrogate storage at request time
3. keep a nil-safe guard around the middleware’s LoadOrStore result

Patch fragment:

diff --git a/app.go b/app.go
index ... .. ...
--- a/app.go
+++ b/app.go
@@
 func (s SouinApp) Provision(_ caddy.Context) error {
 	return nil
 }
+
+func (s *SouinApp) getSurrogateStorage() providers.SurrogateInterface {
+	if s.SurrogateStorage != nil {
+		return s.SurrogateStorage
+	}
+
+	up.Range(func(key, value any) bool {
+		if key != surrogate_key || value == nil {
+			return true
+		}
+
+		storage, ok := value.(providers.SurrogateInterface)
+		if !ok {
+			return true
+		}
+
+		s.SurrogateStorage = storage
+		return false
+	})
+
+	return s.SurrogateStorage
+}
diff --git a/admin.go b/admin.go
index ... .. ...
--- a/admin.go
+++ b/admin.go
@@
 func (a *adminAPI) regenerateHandlerMap() {
 	config := Configuration{
 		API: a.app.API,
 		DefaultCache: DefaultCache{
 			TTL: configurationtypes.Duration{
 				Duration: 120 * time.Second,
 			},
 		},
 	}
 
-	a.InternalEndpointHandlers = api.GenerateHandlerMap(&config, a.app.Storers, a.app.SurrogateStorage)
+	a.InternalEndpointHandlers = api.GenerateHandlerMap(&config, a.app.Storers, a.app.getSurrogateStorage())
 }
diff --git a/httpcache.go b/httpcache.go
index ... .. ...
--- a/httpcache.go
+++ b/httpcache.go
@@
 	bh := middleware.NewHTTPCacheHandler(&s.Configuration)
 	surrogates, ok := up.LoadOrStore(surrogate_key, bh.SurrogateKeyStorer)
-	if ok {
+	if ok && surrogates != nil {
 		bh.SurrogateKeyStorer = surrogates.(surrogates_providers.SurrogateInterface)
 	}

Also related: https://caddy.community/t/caddyserver-cache-handler-doesnt-purge-by-surrogate-key/30857/5