Stop exporting HOSTNAME from scripts

[jasontedor]

Today we explicitly export the HOSTNAME variable from scripts. This is probably a relic from the days when the scripts were not run on bash but instead assume a POSIX-compliant shell only where HOSTNAME is not guaranteed to exist. Yet, bash guarantees that HOSTNAME is set so we do not need to set it in scripts. This commit removes this legacy.

[jaymode]

LGTM

[shaharmor]

Hey,
This PR removed support for using ${HOSTNAME} in the elasticsearch.yml config file for dynamically setting the node.name property.

Was this intentional? I'm pretty sure this is a rather newish feature. Ref: #9474

[jasontedor]

@shaharmor It did not remove support for that, you can still set in the elasticsearch.yml and it will be observed. The only thing that it removed is ensuring that HOSTNAME is set by the startup scripts. We do not need to do this, bash guarantees that HOSTNAME is set (which is now required), and users can still it themselves explicitly in /etc/default/elasticsearch or /etc/sysconfig/elasticsearch if needed.

[shaharmor]

Well, it doesn't work for me :) On ES 6 beta 1

This is my elasticsearch.yml file:

cluster.name: test
path.data: /data/elasticsearch
path.logs: /var/log/elasticsearch
discovery.zen.ping.unicast.hosts:
  - 'elasticsearch-data-001'
  - 'elasticsearch-data-002'
  - 'elasticsearch-data-003'

node.name: ${HOSTNAME}
node.master: true
node.data: true
node.max_local_storage_nodes: 1

network.host:
  - '_site_'
  - '_local_'

bootstrap.memory_lock: true
http.cors.enabled: true
http.cors.allow-origin: "*"

OS:

Distributor ID:	Ubuntu
Description:	Ubuntu 16.04.3 LTS
Release:	16.04
Codename:	xenial

And HOSTNAME is an existing environment variable:

root@elasticsearch-data-001:~# bash -c 'echo $HOSTNAME'
elasticsearch-data-001

When starting using systemctl restart elasticsearch.service, i'm getting the following error in journalctl -u elasticsearch.service:

Aug 17 11:22:38 elasticsearch-data-001 systemd[1]: Started Elasticsearch.
Aug 17 11:22:50 elasticsearch-data-001 elasticsearch[104026]: Exception in thread "main" java.lang.IllegalArgumentException: Could not resolve placeholder 'HOSTNAME'
Aug 17 11:22:50 elasticsearch-data-001 elasticsearch[104026]:         at org.elasticsearch.common.settings.PropertyPlaceholder.parseStringValue(PropertyPlaceholder.java:116)
Aug 17 11:22:50 elasticsearch-data-001 elasticsearch[104026]:         at org.elasticsearch.common.settings.PropertyPlaceholder.replacePlaceholders(PropertyPlaceholder.java:69)
Aug 17 11:22:50 elasticsearch-data-001 elasticsearch[104026]:         at org.elasticsearch.common.settings.Settings$Builder.replacePropertyPlaceholders(Settings.java:1117)
Aug 17 11:22:51 elasticsearch-data-001 systemd[1]: elasticsearch.service: Main process exited, code=exited, status=1/FAILURE
Aug 17 11:22:51 elasticsearch-data-001 systemd[1]: elasticsearch.service: Unit entered failed state.
Aug 17 11:22:51 elasticsearch-data-001 systemd[1]: elasticsearch.service: Failed with result 'exit-code'.

This is after an apt-get dist-upgrade that upgraded ES from latest alpha to beta1. In the alpha it worked flawlessly.

[jasontedor]

It's probably systemd, I'll take a look later. Would you mind opening a new issue with these details and ping me on it? Thanks for trying out the beta!