session: sort MacaroonRecipe.caveats in migration

In the kvdb to sql migration, if there have been caveats set for the
MacaroonRecipe, the order of the postgres db caveats will in very rare
cases differ from the kv store caveats. Therefore, we sort both the kv
and sql caveats by their ID, so that we can compare them in a
deterministic way.

Author: ViktorT-11

session/sql_migration.go

@@ -7,6 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"reflect"
+	"sort"
 	"time"
 
 	"github.com/davecgh/go-spew/spew"
@@ -380,17 +381,45 @@ func overrideSessionTimeZone(session *Session) {
 // as nil in the bbolt store. Therefore, we also override the permissions
 // or caveats to nil for the migrated session in that scenario, so that the
 // deep equals check does not fail in this scenario either.
+//
+// Additionally, we sort the caveats of both the kv and sql sessions by
+// their ID, so that they are always comparable in a deterministic way with deep
+// equals.
 func overrideMacaroonRecipe(kvSession *Session, migratedSession *Session) {
 	if kvSession.MacaroonRecipe != nil {
 		kvPerms := kvSession.MacaroonRecipe.Permissions
 		kvCaveats := kvSession.MacaroonRecipe.Caveats
 
+		// If the kvSession has a MacaroonRecipe with nil set for any
+		// of the fields, we need to override the migratedSession
+		// MacaroonRecipe to match that.
 		if kvPerms == nil && kvCaveats == nil {
 			migratedSession.MacaroonRecipe = &MacaroonRecipe{}
 		} else if kvPerms == nil {
 			migratedSession.MacaroonRecipe.Permissions = nil
 		} else if kvCaveats == nil {
 			migratedSession.MacaroonRecipe.Caveats = nil
 		}
+
+		sqlCaveats := migratedSession.MacaroonRecipe.Caveats
+
+		// If there have been caveats set for the MacaroonRecipe,
+		// the order of the postgres db caveats will in very rare cases
+		// differ from the kv store caveats. Therefore, we sort
+		// both the kv and sql caveats by their ID, so that we can
+		// compare them in a deterministic way.
+		if kvCaveats != nil {
+			sort.Slice(kvCaveats, func(i, j int) bool {
+				return bytes.Compare(
+					kvCaveats[i].Id, kvCaveats[j].Id,
+				) < 0
+			})
+
+			sort.Slice(sqlCaveats, func(i, j int) bool {
+				return bytes.Compare(
+					sqlCaveats[i].Id, sqlCaveats[j].Id,
+				) < 0
+			})
+		}
 	}
 }