refactor(session): wrap own error type instead of using store-specific errors

pkg/handler/handler_callback.go

@@ -17,7 +17,6 @@ import (
 )
 
 func (h *Handler) Callback(w http.ResponseWriter, r *http.Request) {
-
 	// unconditionally clear login cookie
 	h.clearLoginCookies(w)
 

pkg/handler/handler_logout.go

@@ -5,11 +5,11 @@ import (
 	"fmt"
 	"net/http"
 
-	"github.com/go-redis/redis/v8"
 	log "github.com/sirupsen/logrus"
 
 	"github.com/nais/wonderwall/pkg/cookie"
 	logentry "github.com/nais/wonderwall/pkg/middleware"
+	"github.com/nais/wonderwall/pkg/session"
 )
 
 // Logout triggers self-initiated for the current user
@@ -22,7 +22,7 @@ func (h *Handler) Logout(w http.ResponseWriter, r *http.Request) {
 	if err == nil && sessionData != nil {
 		idToken = sessionData.IDToken
 		err = h.destroySession(w, r, h.localSessionID(sessionData.ExternalSessionID))
-		if err != nil && !errors.Is(err, redis.Nil) {
+		if err != nil && !errors.Is(err, session.KeyNotFoundError) {
 			h.InternalError(w, r, fmt.Errorf("logout: destroying session: %w", err))
 			return
 		}

pkg/handler/session.go

@@ -7,7 +7,6 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/go-redis/redis/v8"
 	"github.com/sethvargo/go-retry"
 
 	"github.com/nais/wonderwall/pkg/cookie"
@@ -38,7 +37,7 @@ func (h *Handler) getSessionFromCookie(w http.ResponseWriter, r *http.Request) (
 		return sessionData, nil
 	}
 
-	if errors.Is(err, redis.Nil) {
+	if errors.Is(err, session.KeyNotFoundError) {
 		return nil, fmt.Errorf("session not found in store: %w", err)
 	}
 
@@ -63,7 +62,7 @@ func (h *Handler) getSession(r *http.Request, sessionID string) (*session.Data,
 		}
 
 		err = fmt.Errorf("reading session data from store: %w", err)
-		if errors.Is(err, redis.Nil) {
+		if errors.Is(err, session.KeyNotFoundError) {
 			return err
 		}
 
@@ -151,7 +150,7 @@ func (h *Handler) destroySession(w http.ResponseWriter, r *http.Request, session
 		}
 
 		err = fmt.Errorf("deleting session from store: %w", err)
-		if errors.Is(err, redis.Nil) {
+		if errors.Is(err, session.KeyNotFoundError) {
 			return err
 		}
 

pkg/session/memory.go

@@ -26,7 +26,7 @@ func (s *memorySessionStore) Read(_ context.Context, key string) (*EncryptedData
 
 	data, ok := s.sessions[key]
 	if !ok {
-		return nil, fmt.Errorf("no such session: %s", key)
+		return nil, fmt.Errorf("%w: no such session: %s", KeyNotFoundError, key)
 	}
 
 	return data, nil

pkg/session/redis.go

@@ -2,6 +2,8 @@ package session
 
 import (
 	"context"
+	"errors"
+	"fmt"
 	"time"
 
 	"github.com/go-redis/redis/v8"
@@ -26,11 +28,15 @@ func (s *redisSessionStore) Read(ctx context.Context, key string) (*EncryptedDat
 	err := metrics.ObserveRedisLatency("Read", func() error {
 		return s.client.Get(ctx, key).Scan(encryptedData)
 	})
-	if err != nil {
-		return nil, err
+	if err == nil {
+		return encryptedData, nil
 	}
 
-	return encryptedData, nil
+	if errors.Is(err, redis.Nil) {
+		return nil, fmt.Errorf("%w: %s", KeyNotFoundError, err.Error())
+	}
+
+	return nil, err
 }
 
 func (s *redisSessionStore) Write(ctx context.Context, key string, value *EncryptedData, expiration time.Duration) error {
@@ -40,7 +46,16 @@ func (s *redisSessionStore) Write(ctx context.Context, key string, value *Encryp
 }
 
 func (s *redisSessionStore) Delete(ctx context.Context, keys ...string) error {
-	return metrics.ObserveRedisLatency("Delete", func() error {
+	err := metrics.ObserveRedisLatency("Delete", func() error {
 		return s.client.Del(ctx, keys...).Err()
 	})
+	if err == nil {
+		return nil
+	}
+
+	if errors.Is(err, redis.Nil) {
+		return fmt.Errorf("%w: %s", KeyNotFoundError, err.Error())
+	}
+
+	return err
 }

pkg/session/session.go

@@ -2,6 +2,7 @@ package session
 
 import (
 	"context"
+	"errors"
 	"time"
 
 	log "github.com/sirupsen/logrus"
@@ -9,6 +10,10 @@ import (
 	"github.com/nais/wonderwall/pkg/config"
 )
 
+var (
+	KeyNotFoundError = errors.New("key not found")
+)
+
 type Store interface {
 	Write(ctx context.Context, key string, value *EncryptedData, expiration time.Duration) error
 	Read(ctx context.Context, key string) (*EncryptedData, error)