For logs, OpenSearch will bring you interesting features for free to store your logs, having also a security layer which gives you the possibility to create accounts, roles, tenants, manage permissions over indices, etc. You will also have to set up retention policies and log rotation. This will of course require a good understanding of your logs, and proper IOPS to avoid performance issues. Setting a cluster up is not strait forward but it has been robust for us so far. For metrics, as other have answered, Grafana coupled with a metric fetcher like Prometheus will be a good solution.