Elasticsearch: Changing data directory on an Amazon Linux Machine - elasticsearch

Question

I have installed Elasticsearch on an Amazon Linux Machine using the latest rpm package from their website. After thatt, I have attached an EBS volume and created a directory on this volume. I want this directory to be the data directory of Elasticsearch. So, I started the elasticsearch service first with defaults. I created a new directory in the user ec2-user home directory
mkdir my_data
Then I changed the path.data in the /etc/elasticsearch/elasticsearch.yml file to point to this new directory
path.data: /home/ec2-user/my_data
Then I changed the ownership of this directory:
sudo chown -R elasticsearch:elasticsearch /home/ec2-user/my_data
So, currently the permissions look like this
[ec2-user#ip-XXXXXX ~]$ ls -lrt
total 28632
drwxrwxr-x 2 elasticsearch elasticsearch 4096 Feb 4 06:18 my_data
However, when I try to start elasticsearch, I get the error:
Starting elasticsearch: Exception in thread "main" java.lang.IllegalStateException: Unable to access 'path.data' (/home/ec2-user/my_data)
Likely root cause: java.nio.file.AccessDeniedException: /home/ec2-user/my_data
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.createDirectory(UnixFileSystemProvider.java:383)
at java.nio.file.Files.createDirectory(Files.java:630)
at java.nio.file.Files.createAndCheckIsDirectory(Files.java:734)
at java.nio.file.Files.createDirectories(Files.java:720)
at org.elasticsearch.bootstrap.Security.ensureDirectoryExists(Security.java:337)
at org.elasticsearch.bootstrap.Security.addPath(Security.java:314)
at org.elasticsearch.bootstrap.Security.addFilePermissions(Security.java:256)
at org.elasticsearch.bootstrap.Security.createPermissions(Security.java:212)
at org.elasticsearch.bootstrap.Security.configure(Security.java:118)
at org.elasticsearch.bootstrap.Bootstrap.setupSecurity(Bootstrap.java:196)
at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:167)
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]

Answer 1

I found it surprising, but in the latest version of Elasticsearch, if you create a data directory inside home of other user, ES is unable to access it. Though logically it is perfect too. What i suggest that you either mount an external hard disk for elasticsearch or create a data directory inside /home/ on the parallel of ec2-user. so you directory should have a path /home/my-data and it will work like a charm. :)
Thanks ,
Bharvi

Answer 2

In case this helps anyone with the problem that I was seeing...
This seems to be an oddity with java.nio.file.Files.createDirectories. The doc says "Unlike the createDirectory method, an exception is not thrown if the directory could not be created because it already exists." In your case, the folder exists so you should not get an exception. But the check for existence done in UnixFileSystemProvider is via mkdir which will throw an access-denied exception before it throws an already-exists exception. The access-denied exception which you are seeing then is not that elasticsearch doesn't have access to /home/ec2-user/my_data but rather that it doesn't have access to make that directory. So the solution is to fix the permission problem that is preventing elasticsearch from making the directory /home/ec2-user/my_data. For you this would be to make /home/ec2-user writeable by elasticsearch or to create a path like /home/ec2-user/my_data_holder/my_data and then make /home/ec2-user/my_data_holder writeable by elasticsearch.