Two docker containers running on same VM & network - how to curl <https://url:port> on "container A" from "container B"

General
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  1. Two docker containers running on the same VM/host.
    Container A = elasticsearch on port 9200.
    Container B = ubuntu 16:04.

  2. Cronjob setup in Container B to hit elasticsearch (container A).
    curl https://localhost:9200 fails to connect to container A.

What are the things that needs to be accomplished to be able to hit container A’s 9200 port from container B?