# Logstash fails to run if data.path is a symlink

**URL:** <https://discuss.elastic.co/t/logstash-fails-to-run-if-data-path-is-a-symlink/134674>\
**Category:** Logstash\
**Created:** [June 5, 2018, 6:22pm UTC](https://discuss.elastic.co/t/logstash-fails-to-run-if-data-path-is-a-symlink/134674 "2018-06-05T18:22:31Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![altmind](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/altmind/32/31962_2.png) [@altmind](https://discuss.elastic.co/u/altmind)\
**Post date:** [June 5, 2018, 6:22pm UTC](https://discuss.elastic.co/t/logstash-fails-to-run-if-data-path-is-a-symlink/134674/1 "2018-06-05T18:22:31Z")

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I host /var/lib/logstash on a separate partition, this directory is a symlink elsewhere.

Logstash fails to start with the following error message in logs:

> [2018-06-05T13:12:24,295][INFO][logstash.modules.scaffold] Initializing module {:module\_name=\>"fb\_apache", :directory=\>"/usr/share/logstash/modules/fb\_apache/configuration"}  
> [2018-06-05T13:12:24,300][INFO][logstash.modules.scaffold] Initializing module {:module\_name=\>"netflow", :directory=\>"/usr/share/logstash/modules/netflow/configuration"}  
> [2018-06-05T13:12:24,456][INFO][logstash.modules.scaffold] Initializing module {:module\_name=\>"arcsight", :directory=\>"/usr/share/logstash/vendor/bundle/jruby/2.3.0/gems/x-pack-6.2.4-java/modules/arcsight/configuration"}  
> [2018-06-05T13:12:24,674][FATAL][logstash.runner] An unexpected error occurred! {:error=\>java.nio.file.FileAlreadyExistsException: /var/lib/logstash, :backtrace=\>["sun.nio.fs.UnixException.translateToIOException(sun/nio/fs/UnixException.java:88)", "sun.nio.fs.UnixException.rethrowAsIOException(sun/nio/fs/UnixException.java:102)", "sun.nio.fs.UnixException.rethrowAsIOException(sun/nio/fs/UnixException.java:107)", "sun.nio.fs.UnixFileSystemProvider.createDirectory(sun/nio/fs/UnixFileSystemProvider.java:384)", "java.nio.file.Files.createDirectory(java/nio/file/Files.java:674)", "java.nio.file.Files.createAndCheckIsDirectory(java/nio/file/Files.java:781)", "java.nio.file.Files.createDirectories(java/nio/file/Files.java:727)", "org.logstash.FileLockFactory.obtainLock(org/logstash/FileLockFactory.java:57)", "java.lang.reflect.Method.invoke(java/lang/reflect/Method.java:498)", "org.jruby.javasupport.JavaMethod.invokeDirectWithExceptionHandling(org/jruby/javasupport/JavaMethod.java:468)", "org.jruby.javasupport.JavaMethod.invokeStaticDirect(org/jruby/javasupport/JavaMethod.java:370)", "RUBY.execute(/usr/share/logstash/logstash-core/lib/logstash/runner.rb:335)", "RUBY.run(/usr/share/logstash/vendor/bundle/jruby/2.3.0/gems/clamp-0.6.5/lib/clamp/command.rb:67)", "RUBY.run(/usr/share/logstash/logstash-core/lib/logstash/runner.rb:219)", "RUBY.run(/usr/share/logstash/vendor/bundle/jruby/2.3.0/gems/clamp-0.6.5/lib/clamp/command.rb:132)", "usr.share.logstash.lib.bootstrap.environment.invokeOther55:run(usr/share/logstash/lib/bootstrap//usr/share/logstash/lib/bootstrap/environment.rb:67)", "usr.share.logstash.lib.bootstrap.environment.(/usr/share/logstash/lib/bootstrap/environment.rb:67)", "java.lang.invoke.MethodHandle.invokeWithArguments(java/lang/invoke/MethodHandle.java:627)", "org.jruby.Ruby.runScript(org/jruby/Ruby.java:828)", "org.jruby.Ruby.runNormally(org/jruby/Ruby.java:747)", "org.jruby.Ruby.runNormally(org/jruby/Ruby.java:765)", "org.jruby.Ruby.runFromMain(org/jruby/Ruby.java:578)", "org.logstash.Logstash.run(org/logstash/Logstash.java:81)", "org.logstash.Logstash.main(org/logstash/Logstash.java:45)"]}  
> [2018-06-05T13:12:24,677][ERROR][org.logstash.Logstash] java.lang.IllegalStateException: org.jruby.exceptions.RaiseException: (SystemExit) exit

Feels like we fail when trying to create a lock file, because logstash uses Files.createDirectories(and it does not follow symlinks):

> <https://github.com/elastic/logstash/blob/main/logstash-core/src/main/java/org/logstash/FileLockFactory.java#L52>

This issue was already highlighted there without any response: [Startup fails if path.data is a symlink](https://discuss.elastic.co/t/startup-fails-if-path-data-is-a-symlink/118669)

Can we please add additional check if data.dir already exist before  
calling Files.createDirectories?

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**Author:** ![danhermann](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/danhermann/32/33024_2.png) [@danhermann](https://discuss.elastic.co/u/danhermann)\
**Post date:** [June 20, 2018, 12:16pm UTC](https://discuss.elastic.co/t/logstash-fails-to-run-if-data-path-is-a-symlink/134674/2 "2018-06-20T12:16:48Z")

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I've merged your fix below for this. Thanks for your contribution!

> <https://github.com/elastic/logstash/pull/9706>

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 18, 2018, 12:16pm UTC](https://discuss.elastic.co/t/logstash-fails-to-run-if-data-path-is-a-symlink/134674/3 "2018-07-18T12:16:51Z")

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