Configuring gitlab-ci.yml to add private key without display it in logs


I have some gitlab-ci.yml configured for rsync, capistrano and for this needs I configured this jobs with this documentation :
Everything work fine.

But I can see my private key on pipeline logs… And I want to avoid this behaviour.
The same is happening here :
rsync -rz --stats --exclude “stats” --delete -e “ssh -p $RSYNC_PORT” ./build/ “$RSYNC_USER@$RSYNC_HOST:$RSYNC_PATH”;

So can you help me to find the right “way” to don’t display variables :
echo “$SSH_PRIVATE_KEY” | tr -d ‘\r’ | ssh-add - > /dev/null

Thanks for your help,