Backport of #49612.
The current Docker entrypoint script picks up environment variables and
translates them into -E command line arguments. However, since any tool
executes via `docker exec` doesn't run the entrypoint, it results in
a poorer user experience.
Therefore, refactor the env var handling so that the -E options are
generated in `elasticsearch-env`. These have to be appended to any
existing command arguments, since some CLI tools have subcommands and
-E arguments must come after the subcommand.
Also extract the support for `_FILE` env vars into a separate script, so
that it can be called from more than once place (the behaviour is
idempotent).
Finally, add noop -E handling to CronEvalTool for parity, and support
`-E` in MultiCommand before subcommands.
Remove references to the `platinum` image and add a self-generated trial
licence to the example for TLS on Docker.
Fixeselastic/elasticsearch-docker#176
Although elasticsearch-certutil generates PKCS#12
files which are usable as both keystore and truststore
this is uncommon in practice. Settle these expectations
for the users following our security guides.
Lisa Cawley
Rory Hunter
Alex Pang
Ioannis Kakavas
Toby McLaughlin
Albert Zaharovits
Jason Tedor
Ryan Ernst