title: Spark in docker parquet error No predefined schema found
body: <p>I have a <a href="https://github.com/gettyimages/docker-spark" rel="nofollow">https://github.com/gettyimages/docker-spark</a> based local spark test cluster including R. In particular, this image is used: <a href="https://hub.docker.com/r/possibly/spark/" rel="nofollow">https://hub.docker.com/r/possibly/spark/</a></p>
  
  <p>Trying to read a parquet file with <strong>sparkR</strong> this exception occurs. Reading a parquet file works without any problems on a local spark installation.</p>
  
  <pre><code>     myData.parquet &lt;- read.parquet(sqlContext, "/mappedFolder/myFile.parquet")
  16/03/29 20:36:02 ERROR RBackendHandler: parquet on 4 failed
  Fehler in invokeJava(isStatic = FALSE, objId$id, methodName, ...) : 
    java.lang.AssertionError: assertion failed: No predefined schema found, and no Parquet data files or summary files found under file:/mappedFolder/myFile.parquet.
      at scala.Predef$.assert(Predef.scala:179)
      at org.apache.spark.sql.execution.datasources.parquet.ParquetRelation$MetadataCache.org$apache$spark$sql$execution$datasources$parquet$ParquetRelation$MetadataCache$$readSchema(ParquetRelation.scala:512)
      at org.apache.spark.sql.execution.datasources.parquet.ParquetRelation$MetadataCache$$anonfun$12.apply(ParquetRelation.scala:421)
      at org.apache.spark.sql.execution.datasources.parquet.ParquetRelation$MetadataCache$$anonfun$12.apply(ParquetRelation.scala:421)
      at scala.Option.orElse(Option.scala:257)
      at org.apache.spark.sql.execution.datasources.parquet.ParquetRelation$MetadataCache.refresh(ParquetRelation.scala:421)
      at org.apache.spark.sql.execution.datasources.parquet.ParquetRelation.org$apache$spark$sql$execution$datasources$parquet$ParquetRelation$$metadataCac
  </code></pre>
  
  <p>Strangely the same error is the same - even for not existing files.</p>
  
  <p>However in the terminal I can see that the files are there:</p>
  
  <pre><code>    /mappedFolder/myFile.parquet
      root@worker:/mappedFolder/myFile.parquet# ls
      _common_metadata                                              part-r-00097-e5221f6f-e125-4f52-9f6d-4f38485787b3.gz.parquet  part-r-00196-e5221f6f-e125-4f52-9f6d-4f38485787b3.gz.parquet
  ....
  </code></pre>