Backing up an ephemeral Elasticsearch installation I have an installation of Elasticsearch without persistence running and I need to back it up so we can move it to a persistent setup.

What are safe ways to do this and keep the data in the ES database?

It is running and I want to avoid shutting it down.

It is running in a container and I think the entrypoint starts the server. So stopping the cluster my stop my pod and get rid of all my data...
ElasticSearch can backup itself when told to do so via an API call.
You just need to configure a destination, and optionally credentials, for example you make ElasticSearch create snapshots of its database in AWS S3.

https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-snapshots.html

You can also automate these calls using a schedule with the Elastic curator tool.

https://www.elastic.co/guide/en/elasticsearch/client/curator/5.5/snapshot.html