Issue with Elasticsearch : ConnectionError - django

Question

I'm working on different web application in my new society and I get this issue each time I would like to use Elasticsearch (version 6.3.2) :
elasticsearch.exceptions.ConnectionError: ConnectionError(<urllib3.connection.HTTPConnection object at 0x7f4e2ab26438>: Failed to establish a new connection: [Errno 111] Connection refused) caused by: NewConnectionError(<urllib3.connection.HTTPConnection object at 0x7f4e2ab26438>: Failed to establish a new connection: [Errno 111] Connection refused)
For example with Django, I execute these commands :
sudo service elasticsearch start
then
python manage.py indexdocs
And I get this issue as below. I tried to make :
curl -XGET http://localhost:9200
And I obtain this : curl: (7) Failed to connect to localhost port 9200: Connexion refusée
Do you have any idea about this ? I have to authorized something somewhere ?
Thank you
EDIT :
In /var/log/elasticsearch/elasticsearch.log I have a loop issue :
[2018-08-28T09:27:56,673][INFO ][o.e.n.Node ] [] initializing ...
[2018-08-28T09:27:56,733][INFO ][o.e.e.NodeEnvironment ] [DRmGsVp] using [1] data paths, mounts [[/ (/dev/sda1)]], net usable_space [25.5gb], net total_space [39.1gb], types [ext4]
[2018-08-28T09:27:56,734][INFO ][o.e.e.NodeEnvironment ] [DRmGsVp] heap size [1.9gb], compressed ordinary object pointers [true]
[2018-08-28T09:27:56,749][INFO ][o.e.n.Node ] [DRmGsVp] node name derived from node ID [DRmGsVpYQ8W4E4JTZoM1Lw]; set [node.name] to override
[2018-08-28T09:27:56,749][INFO ][o.e.n.Node ] [DRmGsVp] version[6.4.0], pid[6436], build[default/deb/595516e/2018-08-17T23:18:47.308994Z], OS[Linux/4.15.0-33-generic/amd64], JVM[Oracle Corporation/Java HotSpot(TM) 64-Bit Server VM/1.8.0_181/25.181-b13]
[2018-08-28T09:27:56,749][INFO ][o.e.n.Node ] [DRmGsVp] JVM arguments [-Xms2g, -Xmx2g, -XX:+UseConcMarkSweepGC, -XX:CMSInitiatingOccupancyFraction=75, -XX:+UseCMSInitiatingOccupancyOnly, -XX:+AlwaysPreTouch, -Xss1m, -Djava.awt.headless=true, -Dfile.encoding=UTF-8, -Djna.nosys=true, -XX:-OmitStackTraceInFastThrow, -Dio.netty.n$
[2018-08-28T09:27:57,892][ERROR][o.e.b.Bootstrap ] Exception
java.lang.IllegalArgumentException: Plugin [ingest-attachment] was built for Elasticsearch version 6.3.2 but version 6.4.0 is running
at org.elasticsearch.plugins.PluginsService.verifyCompatibility(PluginsService.java:339) ~[elasticsearch-6.4.0.jar:6.4.0]

Answer 1

the problem is about incompatibility between ingest-plugin and elasticsearch.
I suggest download ingest-plugin version 6.4. or remove it.
sudo bin/elasticsearch-plugin install ingest-attachment
sudo bin/elasticsearch-plugin remove ingest-attachment
This plugin can be downloaded for offline install from https://artifacts.elastic.co/downloads/elasticsearch-plugins/ingest-attachment/ingest-attachment-6.4.0.zip.
offline install:
To install a plugin from your local file system at /path/to/plugin.zip, you could run:
sudo bin/elasticsearch-plugin install file:///path/to/plugin.zip