Upgrade elasticsearch-oss to v7.8.0 and Open Distro for Elasticsearch v1.9.0

[toszo]

Is your feature request related to a problem? Please describe.
Currently Epiphany is on ELasticsearch Open Distro version 1.3.0 which is equivalent to the Elastic 7.3.2 release.

Describe the solution you'd like
We require certain Kibana features from the latest Elasticsearch release 7.8.0 (Open Distro 1.9.0). We are planning to make use of the new Kibana features in DE Q4 release.

Describe alternatives you've considered
No.

Additional context
Upgrade OpenDistro (ElasticSearch, Kibana) to the latest version:
https://opendistro.github.io/for-elasticsearch-docs/docs/install/

Upgrading cluster: https://opendistro.github.io/for-elasticsearch-docs/docs/upgrade/rolling/

Upgrading to 1.8.0 (breaking change):
https://opendistro.github.io/for-elasticsearch-docs/docs/upgrade/1-8-0/

[toszo]

Most probably requires also to upgrade Filebeat #846

[rafzei]

@to-bar shouldn't this be in 'on hold' instead of 'to-do' ?

[to-bar]

@to-bar shouldn't this be in 'on hold' instead of 'to-do' ?

Moved to Blocked because of #1647.

[to-bar]

During testing I found this regression bug in Elasticsearch v7.8.0. It was fixed in ES 7.8.1, see PR.

It's not possible to upgrade only Elasticsearch without Open Distro for Elasticsearch, for example:

apt-get install opendistro-alerting
The following packages have unmet dependencies:\n opendistro-alerting : Depends: elasticsearch-oss (= 7.8.0) but 7.8.1 is to be installed
E: Unable to correct problems, you have held broken packages.

ODFE just released new version (1.10.1), see here.