elasticsearch 에서 keystore 파일을 읽지 못함(.deb package 설치)

Describe the feature:

Elasticsearch version (bin/elasticsearch --version):Version: 6.0.0-beta2-SNAPSHOT, Build: d6a7e25/2017-08-28T13:34:58.542Z, JVM: 1.8.0_141

Plugins installed: [x-pack]

JVM version (java -version): openjdk version "1.8.0_141"

OS version (uname -a if on a Unix-like system): Linux packer-virtualbox-iso-1501424719 4.4.0-87-generic #110~14.04.1-Ubuntu SMP Tue Jul 18 14:51:32 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

Description of the problem including expected versus actual behavior: 5.6.0-SNAPSHOT (with x-pack) 에서 6.0.0-beta2-SNAPSHOT 으로 업그레이드 후에 elasticsearch 가 /etc/elasticsearch/elasticsearch.keystor 파일을 읽지 못하여 실행이 되지 않는다.

Steps to reproduce:

Please include a minimal but complete recreation of the problem, including
(e.g.) index creation, mappings, settings, query etc. The easier you make for
us to reproduce it, the more likely that somebody will take the time to look at it.

1. 5.6.0 elasticsearch 와 x-pack (links below) 설치
2. production mode (network.host: 0.0.0.0) 에서 실행하고, 기본 비밀번호로 바꿈
3. service elasticsearch stop
4. /usr/share/elasticsearch/bin/elasticsearch-plugin remove x-pack
5. 업그레이드 전에 나의 elasticsearch.yml 파일을 백업 했고, 새 설정을 가져온 후에 병합하였다.
6. dpkg -i --force-confnew ./elasticsearch-6.0.0-beta2-SNAPSHOT.deb
7. /usr/share/elasticsearch/bin/elasticsearch-plugin install -b file:///vagrant/qa/x-pack-6.0.0-beta2-SNAPSHOT.zip
8. service elasticsearch start 아래 로그 참조
9. -rw------- 1 root root 416 Aug 28 19:09 elasticsearch.keystore
   I "fixed" it with;
   chown root:elasticsearch /etc/elasticsearch/elasticsearch.keystore
chmod 660 /etc/elasticsearch/elasticsearch.keystore
   Now Elasticsearch starts

https://snapshots.elastic.co/downloads/elasticsearch/elasticsearch-5.6.0-SNAPSHOT.deb
https://snapshots.elastic.co/downloads/packs/x-pack/x-pack-5.6.0-SNAPSHOT.zip
https://snapshots.elastic.co/downloads/elasticsearch/elasticsearch-6.0.0-beta2-SNAPSHOT.deb
https://snapshots.elastic.co/downloads/packs/x-pack/x-pack-6.0.0-beta2-SNAPSHOT.zip

Provide logs (if relevant):

+ service elasticsearch start
 * Starting Elasticsearch Server
Exception in thread "main" org.elasticsearch.bootstrap.BootstrapException: java.nio.file.AccessDeniedException: /etc/elasticsearch/elasticsearch.keystore
Likely root cause: java.nio.file.AccessDeniedException: /etc/elasticsearch/elasticsearch.keystore
        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 org.apache.lucene.store.SimpleFSDirectory.openInput(SimpleFSDirectory.java:77)
        at org.elasticsearch.common.settings.KeyStoreWrapper.load(KeyStoreWrapper.java:199)
        at org.elasticsearch.bootstrap.Bootstrap.loadSecureSettings(Bootstrap.java:225)
        at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:287)
        at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:130)
        at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:121)
        at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:69)
        at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:134)
        at org.elasticsearch.cli.Command.main(Command.java:90)
        at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:92)
        at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:85)
Refer to the log for complete error details.
   ...fail!