firewalldb: best effort tight coupling of actions and sessions

In this commit, we do our best to ensure that at least at the time of
action creation, if the session ID is set, then our bbolt actions store
impl will at least first check that the session really does exist. This
also forces us to update our tests in preparation for the SQL store
which will tightly couple the actions and sessions.

Author: ellemouton

firewalldb/actions_kvdb.go

@@ -54,9 +54,21 @@ var (
 )
 
 // AddAction serialises and adds an Action to the DB under the given sessionID.
-func (db *BoltDB) AddAction(_ context.Context,
+func (db *BoltDB) AddAction(ctx context.Context,
 	req *AddActionReq) (ActionLocator, error) {
 
+	// If the new action links to a session, the session must exist.
+	// For the bbolt impl of the store, this is our best effort attempt
+	// at ensuring each action links to a session. If the session is
+	// deleted later on, however, then the action will still exist.
+	var err error
+	req.SessionID.WhenSome(func(id session.ID) {
+		_, err = db.sessionIDIndex.GetSession(ctx, id)
+	})
+	if err != nil {
+		return nil, err
+	}
+
 	action := &Action{
 		AddActionReq: *req,
 		AttemptedAt:  db.clock.Now().UTC(),
@@ -69,7 +81,7 @@ func (db *BoltDB) AddAction(_ context.Context,
 	}
 
 	var locator kvdbActionLocator
-	err := db.DB.Update(func(tx *bbolt.Tx) error {
+	err = db.DB.Update(func(tx *bbolt.Tx) error {
 		mainActionsBucket, err := getBucket(tx, actionsBucketKey)
 		if err != nil {
 			return err