lxd hosts fail to start elasticsearch service due to insufficent max_map_count

[Mia Altieri]

When deploying the elasticsearch charm on a localhost lxd cloud, it appears that the charm initally works, but after several minutes when the `update-status` hook re-fires it logs a message `elasticsearch service not running`, on examination of `elasticsearch.service` with `sudo systemctl status elasticsearch.service` it reports itself as not running. The log reported with `sudo cat /var/log/elasticsearch/elasticsearch.log` reports: `max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]`.

To resolve this it is necessary to set `sysctl -w vm.max_map_count=262144` on the host of the lxd container (not the lxd container itself).

As a suggestion it might be useful to add a config option to elasticsearch or log an error if a user has vm.max_map_count > 262144 and is using an lxd cloud

[Eric Chen (eric-chen)]

This charm is no longer being actively maintained. Please consider using the new Canonical Observability Stack (https://charmhub.io/topics/canonical-observability-stack) or the opensearch-operator (https://github.com/canonical/opensearch-operator) instead.