How to monitor Elastic Stack without X-Pack?
All the information should be in the cluster APIs, you'll just lack the visualizations.
Monitoring (of the local cluster) is actually included in X-Pack Basic unlike the other features. Any reason you don't want to use it?
Alternatives include Kopf, Cerebro,... though you'll need to run them as a separate process and watch out for version compatibilities.
We've had success with ElasticHQ for Monitoring (requires python)
https://github.com/ElasticHQ/elasticsearch-HQ
And sentinl for setting up alerts/watchers (it is a plugin for kibana)
https://github.com/sirensolutions/sentinl/wiki
We have set up a reverse proxy to enable ssl/tls and use ubuntu user management to create logins, however, we do not limit access within Kibana itself.
We have little need for graph/machine learning so I am unaware of free alternatives.
The company I work for is heavily Open Source, so these projects suit us.