Plesk Docker Elasticsearch 6.8.6 Memory Error

I’m completely new to Docker & I run a web server Cent OS 7 with Plesk 18.0.21 Update #5 control panel.
I need to run Elasticsearch V6 for Magento 2 websites & thought Docker was the way to go so downloaded the extension & Elasticsearch 6.8.6. but when I try to run it it quits with a memory error:

ERROR: [1] bootstrap checks failed
[1]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]

On the Docker container settings the memory is set to unlimited but I have also set the memory manually but had no effect.

I have seen this error on other forum sites & the answer is to run a cli command but this does not seem to apply to the Plesk version.

I have tried posting this on the Plesk forum but had no replies.

Solved by logging in via terminal & running:

sudo sysctl -w vm.max_map_count=262144

You still need to configure the heap size even if you are limiting memory access to the container!