[gdal-dev] Question on how to open a raster in HDFS using GDAL

[ZAZHIL-HA HERENA]

Thank you for the reply.

Nikos,

The path is correct, the space was an error in my redaction.

James,

I tried to run a GDALINFO in my Linux command line using the GDAL I configured and installed and I am not able to open the raster, even trying to read it from local:

      -bash-4.2$ gdalinfo /vsihdfs/file:/scratch/zherena/test/write/data/rasters/hawaii.tif
      ERROR 4: /vsihdfs/file:/scratch/zherena/test/write/data/rasters/hawaii.tif: No such file or directory
      gdalinfo failed - unable to open '/vsihdfs/file:/scratch/zherena/test/write/data/rasters/hawaii.tif'.

If I try the same commad withouth /vsihdfs/file:/... it works fine.

I also tried:

      -bash-4.2$ gdalinfo --version
      GDAL 2.3.2, released 2018/09/21

Version says 2.3.2 but libraries say: libgdal.so.20.4.2 . I am not sure if I got the latest code, this is the first time I compile it myself, I used this link to download source code:  http://download.osgeo.org/gdal/CURRENT/gdal-2.3.2.tar.gz


And I have a doubt, when configuring I used: --with-hdfs=yes, made another using: --with-hdfs = /scratch/zherena/gdal/hadoop/lib/native. Both tries did not work. I am not really sure what should I pass as a parameter to --with-hdfs?

This is the list of steps I used to build, I am using Java in my application where I plan to use gdal:


  *     make clean distclean(per your suggestion)
  *    ./configure --prefix=/scratch/zherena/gdal/build/gdal-2.3.2/outputb/ --with-complete=yes --with-java=yes --with-swig-java=yes --with-hdfs=/scratch/zherena/gdal/hadoop/lib/native --with-curl=/usr/bin/curl-config
  *   make
  *   make install
  *   cd /swig/java
  *   make veryclean
  *   make
  *   cp *.so ../../outputb/lib/
  *   cp *.jar ../../outputb/lib/


Maybe I am missing something during compile?

Thank you!!
Zazhil-ha
________________________________
From: gdal-dev <gdal-dev-bounces at lists.osgeo.org> on behalf of James McClain <james.mcclain at gmail.com>
Sent: Thursday, November 22, 2018 8:27 PM
Cc: gdal-dev at lists.osgeo.org
Subject: Re: [gdal-dev] Question on how to open a raster in HDFS using GDAL

Hello,

I am the author of the vsihdfs code, I am ready and willing to help.

I just rebuilt it from current master and was able to successfully open an dataset via an HDFS URI with the GDAL Python bindings.  I have a few suggestions.

First, please try putting the file into a local directory and try something like `gdalinfo /vsihdfs/file:/tmp/kahoolawe.tif` to establish a baseline.

Second, if you are using the Python bindings, please make sure that they have been built and installed (and that you are using the ones that you built rather than other ones that exist on your system).  Instructions for building the Python bindings can be found here: https://trac.osgeo.org/gdal/wiki/BuildingOnUnix .

In my case, after building and installing the library and bindings, I was able to successfully open a dataset by starting a python REPL like this:

```bash
export LD_LIBRARY_PATH=$HOME/local/hadoop-2.7.7/lib/native:/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/server:$HOME/local/gdal-master-vsihdfs/lib
export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
export CLASSPATH=$($HOME/local/hadoop-2.7.7/bin/hadoop classpath --glob)
PYTHONPATH=$HOME/local/gdal-master-vsihdfs/lib/python2.7/site-packages python
```

then typing this into it:

```python
from osgeo import gdal, gdalconst
ds = gdal.Open('/vsihdfs/file:/tmp/testfile.tif', gdalconst.GA_ReadOnly)
```

(I do not have easy access to and HDFS cluster right at the moment, so I only tested a local HDFS URI.)

A note: After having done a build without HDFS support in the tree, I had do a `make clean distclean` before I was able to get a build with working HDFS support.

Sincerely,
James McClain

On Thu, Nov 22, 2018 at 8:13 PM Nikos Alexandris <nik at nikosalexandris.net<mailto:nik at nikosalexandris.net>> wrote:
* ZAZHIL-HA HERENA <zazhil_ha at hotmail.com<mailto:zazhil_ha at hotmail.com>> [2018-11-22 22:35:32 +0000]:

>Hello, I am not sure if I should use this mailing list to ask questions but I wanted to try, I am a developer trying to use GDAL to open rasters in HDFS.
>
>
>I read in GDAL documentation that starting 2.4 it is possible to open a raster in HDFS. I downloaded and compiled the latest source code available version and the generated libraries show it is 2.4 (libgdal.so.20.4.2). I compiled with option "-with-hdfs=yes" and "--with-java=yes".
>
>I am trying to open a raster using:
>
>
>
>    Dataset raster = gdal.Open("/vsihdfs/hdfs://node:8020/user/hdfs /spatial_raster/input_raster/kahoolawe.tif", gdalconst.GA_ReadOnly);

Is your path correct? There is a space here (in "/hfds /").

Nikos

>
>
>but I am getting the following error: "ERROR 4: No such file or directory"

[rest deleted]
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