Add proper error message if session provider can not be created (#35520)

the middleware that creates the session provider just panics if on
creation the config is wrong.
this is not catched and so you just get an cryptic stacktrace with no
point where to look at (as user).

## Before

```
2025/09/16 03:56:37 ...xer/stats/indexer.go:87:populateRepoIndexer() [I] Done (re)populating the repo stats indexer with existing repositories
2025/09/16 03:56:37 modules/ssh/ssh.go:387:Listen() [I] Adding SSH host key: /var/lib/gitea/data/ssh/gitea.rsa
2025/09/16 03:56:37 modules/ssh/init.go:26:Init() [I] SSH server started on :1234. Cipher list ([chacha20-poly1305@openssh.com aes128-ctr aes192-ctr aes256-ctr aes128-gcm@openssh.com aes256-gcm@openssh.com]), key exchange algorithms ([curve25519-sha256 ecdh-sha2-nistp256 ecdh-sha2-nistp384 ecdh-sha2-nistp521 diffie-hellman-group14-sha256 diffie-hellman-group14-sha1]), MACs ([hmac-sha2-256-etm@openssh.com hmac-sha2-256 hmac-sha1])
2025/09/16 03:56:37 ...s/graceful/server.go:50:NewServer() [I] Starting new SSH server: tcp::1234 on PID: 83337
2025/09/16 03:56:38 cmd/web.go:231:func1() [F] PANIC: dial tcp 127.0.0.1:6379: connect: connection refused
gitea.com/go-chi/session@v0.0.0-20240316035857-16768d98ec96/session.go:239 (0x1cdb908)
code.gitea.io/gitea/routers/common/middleware.go:108 (0x2547f5a)
code.gitea.io/gitea/routers/web/web.go:270 (0x278b8e9)
code.gitea.io/gitea/routers/init.go:185 (0x2850d89)
code.gitea.io/gitea/cmd/web.go:211 (0x295c5ad)
code.gitea.io/gitea/cmd/web.go:262 (0x295cacb)
code.gitea.io/gitea/cmd/main.go:111 (0x2953422)
github.com/urfave/cli/v2@v2.27.2/command.go:276 (0x1cc3dfd)
github.com/urfave/cli/v2@v2.27.2/command.go:269 (0x1cc4084)
github.com/urfave/cli/v2@v2.27.2/app.go:333 (0x1cc086a)
github.com/urfave/cli/v2@v2.27.2/app.go:307 (0x2953f18)
code.gitea.io/gitea/cmd/main.go:172 (0x2953efc)
code.gitea.io/gitea/main.go:46 (0x2998498)
runtime/proc.go:283 (0x4471ca)
runtime/asm_amd64.s:1700 (0x484a20)
```

## After

```
2025/09/22 22:52:35 .../templates/htmlrenderer.go:118:initHTMLRenderer() [D] Creating static HTML Renderer
2025/09/22 22:52:35 routers/web/web.go:273:Routes() [F] common.Sessioner failed: failed to create session middleware: dial tcp 127.0.0.1:6379: connect: connection refused
```

---------

Signed-off-by: 6543 <6543@obermui.de>

go.mod

@@ -16,7 +16,7 @@ require (
 	gitea.com/go-chi/binding v0.0.0-20240430071103-39a851e106ed
 	gitea.com/go-chi/cache v0.2.1
 	gitea.com/go-chi/captcha v0.0.0-20240315150714-fb487f629098
-	gitea.com/go-chi/session v0.0.0-20240316035857-16768d98ec96
+	gitea.com/go-chi/session v0.0.0-20250926004215-636cadd82e15
 	gitea.com/lunny/dingtalk_webhook v0.0.0-20171025031554-e3534c89ef96
 	gitea.com/lunny/levelqueue v0.4.2-0.20230414023320-3c0159fe0fe4
 	github.com/42wim/httpsig v1.2.3

go.sum

@@ -43,8 +43,8 @@ gitea.com/go-chi/cache v0.2.1 h1:bfAPkvXlbcZxPCpcmDVCWoHgiBSBmZN/QosnZvEC0+g=
 gitea.com/go-chi/cache v0.2.1/go.mod h1:Qic0HZ8hOHW62ETGbonpwz8WYypj9NieU9659wFUJ8Q=
 gitea.com/go-chi/captcha v0.0.0-20240315150714-fb487f629098 h1:p2ki+WK0cIeNQuqjR98IP2KZQKRzJJiV7aTeMAFwaWo=
 gitea.com/go-chi/captcha v0.0.0-20240315150714-fb487f629098/go.mod h1:LjzIOHlRemuUyO7WR12fmm18VZIlCAaOt9L3yKw40pk=
-gitea.com/go-chi/session v0.0.0-20240316035857-16768d98ec96 h1:IFDiMBObsP6CZIRaDLd54SR6zPYAffPXiXck5Xslu0Q=
+gitea.com/go-chi/session v0.0.0-20250926004215-636cadd82e15 h1:qFYmz05u/s9664o7+XEgrlHXSPQ4uHO8/ccZGUb1uxA=
-gitea.com/go-chi/session v0.0.0-20240316035857-16768d98ec96/go.mod h1:0iEpFKnwO5dG0aF98O4eq6FMsAiXkNBaDIlUOlq4BtM=
+gitea.com/go-chi/session v0.0.0-20250926004215-636cadd82e15/go.mod h1:0iEpFKnwO5dG0aF98O4eq6FMsAiXkNBaDIlUOlq4BtM=
 gitea.com/lunny/dingtalk_webhook v0.0.0-20171025031554-e3534c89ef96 h1:+wWBi6Qfruqu7xJgjOIrKVQGiLUZdpKYCZewJ4clqhw=
 gitea.com/lunny/dingtalk_webhook v0.0.0-20171025031554-e3534c89ef96/go.mod h1:VyMQP6ue6MKHM8UsOXfNfuMKD0oSAWZdXVcpHIN2yaY=
 gitea.com/lunny/levelqueue v0.4.2-0.20230414023320-3c0159fe0fe4 h1:IFT+hup2xejHqdhS7keYWioqfmxdnfblFDTGoOwcZ+o=

modules/session/db.go

@@ -5,6 +5,7 @@ package session
 
 import (
 	"context"
+	"fmt"
 	"log"
 	"sync"
 
@@ -121,12 +122,12 @@ func (p *DBProvider) Read(sid string) (session.RawStore, error) {
 }
 
 // Exist returns true if session with given ID exists.
-func (p *DBProvider) Exist(sid string) bool {
+func (p *DBProvider) Exist(sid string) (bool, error) {
 	has, err := auth.ExistSession(dbContext(), sid)
 	if err != nil {
-		panic("session/DB: error checking existence: " + err.Error())
+		return false, fmt.Errorf("session/DB: error checking existence: %w", err)
 	}
-	return has
+	return has, nil
 }
 
 // Destroy deletes a session by session ID.
@@ -155,12 +156,12 @@ func (p *DBProvider) Regenerate(oldsid, sid string) (_ session.RawStore, err err
 }
 
 // Count counts and returns number of sessions.
-func (p *DBProvider) Count() int {
+func (p *DBProvider) Count() (int, error) {
 	total, err := auth.CountSessions(dbContext())
 	if err != nil {
-		panic("session/DB: error counting records: " + err.Error())
+		return 0, fmt.Errorf("session/DB: error counting records: %w", err)
 	}
-	return int(total)
+	return int(total), nil
 }
 
 // GC calls GC to clean expired sessions.

modules/session/redis.go

@@ -135,10 +135,12 @@ func (p *RedisProvider) Init(maxlifetime int64, configs string) (err error) {
 // Read returns raw session store by session ID.
 func (p *RedisProvider) Read(sid string) (session.RawStore, error) {
 	psid := p.prefix + sid
-	if !p.Exist(sid) {
+	if exist, err := p.Exist(sid); err == nil && !exist {
 		if err := p.c.Set(graceful.GetManager().HammerContext(), psid, "", p.duration).Err(); err != nil {
 			return nil, err
 		}
+	} else if err != nil {
+		return nil, err
 	}
 
 	var kv map[any]any
@@ -159,9 +161,9 @@ func (p *RedisProvider) Read(sid string) (session.RawStore, error) {
 }
 
 // Exist returns true if session with given ID exists.
-func (p *RedisProvider) Exist(sid string) bool {
+func (p *RedisProvider) Exist(sid string) (bool, error) {
 	v, err := p.c.Exists(graceful.GetManager().HammerContext(), p.prefix+sid).Result()
-	return err == nil && v == 1
+	return err == nil && v == 1, err
 }
 
 // Destroy deletes a session by session ID.
@@ -174,13 +176,18 @@ func (p *RedisProvider) Regenerate(oldsid, sid string) (_ session.RawStore, err
 	poldsid := p.prefix + oldsid
 	psid := p.prefix + sid
 
-	if p.Exist(sid) {
+	if exist, err := p.Exist(sid); err != nil {
+		return nil, err
+	} else if exist {
 		return nil, fmt.Errorf("new sid '%s' already exists", sid)
-	} else if !p.Exist(oldsid) {
+	}
+	if exist, err := p.Exist(oldsid); err == nil && !exist {
 		// Make a fake old session.
-		if err = p.c.Set(graceful.GetManager().HammerContext(), poldsid, "", p.duration).Err(); err != nil {
+		if err := p.c.Set(graceful.GetManager().HammerContext(), poldsid, "", p.duration).Err(); err != nil {
 			return nil, err
 		}
+	} else if err != nil {
+		return nil, err
 	}
 
 	// do not use Rename here, because the old sid and new sid may be in different redis cluster slot.
@@ -211,12 +218,9 @@ func (p *RedisProvider) Regenerate(oldsid, sid string) (_ session.RawStore, err
 }
 
 // Count counts and returns number of sessions.
-func (p *RedisProvider) Count() int {
+func (p *RedisProvider) Count() (int, error) {
 	size, err := p.c.DBSize(graceful.GetManager().HammerContext()).Result()
-	if err != nil {
+	return int(size), err
-		return 0
-	}
-	return int(size)
 }
 
 // GC calls GC to clean expired sessions.

modules/session/virtual.go

@@ -59,8 +59,10 @@ func (o *VirtualSessionProvider) Init(gcLifetime int64, config string) error {
 func (o *VirtualSessionProvider) Read(sid string) (session.RawStore, error) {
 	o.lock.RLock()
 	defer o.lock.RUnlock()
-	if o.provider.Exist(sid) {
+	if exist, err := o.provider.Exist(sid); err == nil && exist {
 		return o.provider.Read(sid)
+	} else if err != nil {
+		return nil, fmt.Errorf("check if '%s' exist failed: %w", sid, err)
 	}
 	kv := make(map[any]any)
 	kv["_old_uid"] = "0"
@@ -68,8 +70,8 @@ func (o *VirtualSessionProvider) Read(sid string) (session.RawStore, error) {
 }
 
 // Exist returns true if session with given ID exists.
-func (o *VirtualSessionProvider) Exist(sid string) bool {
+func (o *VirtualSessionProvider) Exist(sid string) (bool, error) {
-	return true
+	return true, nil
 }
 
 // Destroy deletes a session by session ID.
@@ -87,7 +89,7 @@ func (o *VirtualSessionProvider) Regenerate(oldsid, sid string) (session.RawStor
 }
 
 // Count counts and returns number of sessions.
-func (o *VirtualSessionProvider) Count() int {
+func (o *VirtualSessionProvider) Count() (int, error) {
 	o.lock.RLock()
 	defer o.lock.RUnlock()
 	return o.provider.Count()
@@ -162,9 +164,13 @@ func (s *VirtualStore) Release() error {
 		// Now ensure that we don't exist!
 		realProvider := s.p.provider
 
-		if !s.released && realProvider.Exist(s.sid) {
+		if !s.released {
+			if exist, err := realProvider.Exist(s.sid); err == nil && exist {
 				// This is an error!
 				return fmt.Errorf("new sid '%s' already exists", s.sid)
+			} else if err != nil {
+				return fmt.Errorf("check if '%s' exist failed: %w", s.sid, err)
+			}
 		}
 		realStore, err := realProvider.Read(s.sid)
 		if err != nil {

routers/common/middleware.go

@@ -107,8 +107,8 @@ func ForwardedHeadersHandler(limit int, trustedProxies []string) func(h http.Han
 	return proxy.ForwardedHeaders(opt)
 }
 
-func Sessioner() func(next http.Handler) http.Handler {
+func Sessioner() (func(next http.Handler) http.Handler, error) {
-	return session.Sessioner(session.Options{
+	middleware, err := session.Sessioner(session.Options{
 		Provider:       setting.SessionConfig.Provider,
 		ProviderConfig: setting.SessionConfig.ProviderConfig,
 		CookieName:     setting.SessionConfig.CookieName,
@@ -119,4 +119,9 @@ func Sessioner() func(next http.Handler) http.Handler {
 		SameSite:       setting.SessionConfig.SameSite,
 		Domain:         setting.SessionConfig.Domain,
 	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to create session middleware: %w", err)
+	}
+
+	return middleware, nil
 }

routers/install/routes.go

@@ -8,6 +8,7 @@ import (
 	"html"
 	"net/http"
 
+	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/public"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/web"
@@ -23,7 +24,11 @@ func Routes() *web.Router {
 	base.Methods("GET, HEAD", "/assets/*", public.FileHandlerFunc())
 
 	r := web.NewRouter()
-	r.Use(common.Sessioner(), Contexter())
+	if sessionMid, err := common.Sessioner(); err == nil && sessionMid != nil {
+		r.Use(sessionMid, Contexter())
+	} else {
+		log.Fatal("common.Sessioner failed: %v", err)
+	}
 	r.Get("/", Install) // it must be on the root, because the "install.js" use the window.location to replace the "localhost" AppURL
 	r.Post("/", web.Bind(forms.InstallForm{}), SubmitInstall)
 	r.Get("/post-install", InstallDone)

routers/web/web.go

@@ -267,7 +267,11 @@ func Routes() *web.Router {
 	routes.Get("/ssh_info", misc.SSHInfo)
 	routes.Get("/api/healthz", healthcheck.Check)
 
-	mid = append(mid, common.Sessioner(), context.Contexter())
+	if sessionMid, err := common.Sessioner(); err == nil && sessionMid != nil {
+		mid = append(mid, sessionMid, context.Contexter())
+	} else {
+		log.Fatal("common.Sessioner failed: %v", err)
+	}
 
 	// Get user from session if logged in.
 	mid = append(mid, webAuth(buildAuthGroup()))