ElasticSearch failed to load plugins (License Module) - elasticsearch

Question

I have to load ElasticSearch plugins with the offline instructions but it looks like I am getting a permissions error even when I open up permissions to the files completely and running as root! I've removed and reinstalled as well but this error is consistent.
[root#ip-10-94-146-130 bin]# ./plugin install file:///home/jmblnvr/shield/license-2.1.0.zip
-> Installing from file:/home/jmblnvr/shield/license-2.1.0.zip...
Trying file:/home/jmblnvr/shield/license-2.1.0.zip ...
Downloading .DONE
Verifying file:/home/jmblnvr/shield/license-2.1.0.zip checksums if available ...
NOTE: Unable to verify checksum for downloaded plugin (unable to find .sha1 or .md5 file to verify)
Installed license into /usr/share/elasticsearch/plugins/license
[root#ip-10-94-146-130 bin]# service elasticsearch restart
Stopping elasticsearch: [FAILED]
Starting elasticsearch: Exception in thread "main" java.lang.IllegalStateException: Unable to initialize plugins
Likely root cause: java.nio.file.AccessDeniedException: /usr/share/elasticsearch/plugins/license/plugin-descriptor.properties
at sun.nio.fs.UnixException.translateToIOException(UnixException.java:84)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
at sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:214)
at java.nio.file.Files.newByteChannel(Files.java:361)
at java.nio.file.Files.newByteChannel(Files.java:407)
at java.nio.file.spi.FileSystemProvider.newInputStream(FileSystemProvider.java:384)
at java.nio.file.Files.newInputStream(Files.java:152)
at org.elasticsearch.plugins.PluginInfo.readFromProperties(PluginInfo.java:86)
at org.elasticsearch.plugins.PluginsService.getPluginBundles(PluginsService.java:302)
at org.elasticsearch.plugins.PluginsService.<init>(PluginsService.java:108)
at org.elasticsearch.node.Node.<init>(Node.java:148)
at org.elasticsearch.node.Node.<init>(Node.java:129)
at org.elasticsearch.node.NodeBuilder.build(NodeBuilder.java:145)
at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:178)
at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:285)
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:35)
Refer to the log for complete error details.
[FAILED]
From /var/log:
[root#ip-10-94-146-130 elasticsearch]# cat elasticsearch.log
[2015-12-15 11:44:24,525][INFO ][node ] [Valtorr] stopping ...
[2015-12-15 11:44:24,639][INFO ][node ] [Valtorr] stopped
[2015-12-15 11:44:24,641][INFO ][node ] [Valtorr] closing ...
[2015-12-15 11:44:24,647][INFO ][node ] [Valtorr] closed
[2015-12-15 11:44:26,097][WARN ][bootstrap ] unable to install syscall filter: seccomp unavailable: CONFIG_SECCOMP not compiled into kernel, CONFIG_SECCOMP and CONFIG_SECCOMP_FILTER are needed
[2015-12-15 11:44:26,314][INFO ][node ] [Agon] version[2.1.0], pid[21703], build[72cd1f1/2015-11-18T22:40:03Z]
[2015-12-15 11:44:26,314][INFO ][node ] [Agon] initializing ...
[2015-12-15 11:44:26,318][ERROR][bootstrap ] Exception
java.lang.IllegalStateException: Unable to initialize plugins
at org.elasticsearch.plugins.PluginsService.<init>(PluginsService.java:111)
at org.elasticsearch.node.Node.<init>(Node.java:148)
at org.elasticsearch.node.Node.<init>(Node.java:129)
at org.elasticsearch.node.NodeBuilder.build(NodeBuilder.java:145)
at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:178)
at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:285)
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:35)
Caused by: java.nio.file.AccessDeniedException: /usr/share/elasticsearch/plugins/license/plugin-descriptor.properties
at sun.nio.fs.UnixException.translateToIOException(UnixException.java:84)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
at sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:214)
at java.nio.file.Files.newByteChannel(Files.java:361)
at java.nio.file.Files.newByteChannel(Files.java:407)
at java.nio.file.spi.FileSystemProvider.newInputStream(FileSystemProvider.java:384)
at java.nio.file.Files.newInputStream(Files.java:152)
at org.elasticsearch.plugins.PluginInfo.readFromProperties(PluginInfo.java:86)
at org.elasticsearch.plugins.PluginsService.getPluginBundles(PluginsService.java:302)
at org.elasticsearch.plugins.PluginsService.<init>(PluginsService.java:108)
... 6 more

Answer 1

I was having the same sort of exception but after installing and while loading x-pack plugin on Elasticsearch 5.2.1:
Caused by: java.nio.file.AccessDeniedException: /usr/share/elasticsearch/plugins/x-pack/plugin-descriptor.properties
In my case, I started by adding elasticsearch user to the root group:
usermod -aG root elasticsearch
Afterwards, it was only necessary to modify the ownership of the plugins folder:
chown -R elasticsearch:elasticsearch /usr/share/elasticsearch/plugins/

Answer 2

Thanks to Val, simple solution is after installing plugins you need to quickly change ownership/groups if you are using the RPM install of Elastic:
chown -R root:elasticsearch /usr/share/elasticsearch