Every time Elasticsearch is updated it fails to start

[jazoom]

Elasticsearch version: 2.0 - 2.4

Plugins installed: [cloud-aws, head, kopf]

JVM version: 1.8.0_101

OS version: Ubuntu 14.04

Description of the problem including expected versus actual behavior:
Elasticsearch servers are updated via Ansible script:

- name: import the Elasticsearch public GPG key into apt
  apt_key: url=https://packages.elastic.co/GPG-KEY-elasticsearch state=present
- name: create Elasticsearch source list
  apt_repository: repo='deb http://packages.elastic.co/elasticsearch/2.x/debian stable main' state=present
- name: install Elasticsearch
  apt: name=elasticsearch state=present update_cache=yes
- name: send Elasticsearch configuration template
  template: src=elasticsearch.j2 dest=/etc/elasticsearch/elasticsearch.yml mode=0644
- name: make Elasticsearch start on system boot
  command: update-rc.d elasticsearch defaults 95 10
- name: start Elasticsearch service
  service: name=elasticsearch state=started

- name: install AWS plugin for Elasticsearch
  elasticsearch_plugin: state=present name="cloud-aws" plugin_bin="/usr/share/elasticsearch/bin/plugin"

- name: restart Elasticsearch service
  service: name=elasticsearch state=restarted

This updates Elasticsearch just fine, but the old version of cloud-aws hangs around. This causes Elasticsearch to fail to start up. This has been causing a headache for every Elasticsearch version for a while now and makes updates a pain.

Is the expected behaviour to remove the plugin before every update?

Steps to reproduce:

1. Run the Ansible task above

[dadoonet]

Please prefer asking questions on discuss.elastic.co.

Yes it's the expected behavior. You need to upgrade the plugin as well.
Don't start Elasticsearch before upgrading the plugin.

[jazoom]

This isn't just a question. I actually thought this was a bug since even if I (manually) update the plugin it still doesn't work. I could find nowhere in the documentation to suggest that plugins should be removed before updating them.

[dadoonet]

Fair enough. The only moment we explained that is in dev guide: https://www.elastic.co/guide/en/elasticsearch/plugins/2.4/plugin-authors.html

We should add this in the main plugin doc probably.

Reopening to fix the doc.

[jazoom]

That sounds like a good idea. I never wanted to author a plugin so I didn't read the dev guide. This knowledge would have saved me quite a lot of debugging time.

[clintongormley]

@jazoom fancy sending a docs PR?