gdalplugin

README

VSI gdal plugin

This folder contains the sources required to build a gdal plugin that will make gdal use the cloud.google.com/go/storage SDK to access any file starting with gs:// passed to GDALOpen. Once the gdal_gcs.so file has been copied to $(GDAL_INSTALL_PREFIX)/lib/gdalplugins/ any program linked to gdal (e.g. gdalinfo, gdal_translate, qgis, etc...) will be able to open gs://bucket/path/to/cog.tif files directly.

Caveats

• This plugin does not work with musl, and therefore cannot be run on alpine like linux distrbutions ( waiting on https://github.com/golang/go/issues/13492 ).
• The internal cache configuration can be tweaked before program startup with the GODAL_BLOCKSIZE and GODAL_NUMBLOCKS environment variables. The default is to cache 1000 bocks of 1Mb. GODAL_BLOCKSIZE may be expressed either as a number of bytes, or a number suffixed with Kb or Mb.
• Although any file format can be accessed through this handler, I/O performance will only be reasonable for "cloud optimized" formats (namely COGs).
• If you only need to access gs:// files from a golang/godal program, it is preferrable to use godal.RegisterGCSHandler() directly rather than using this plugin in order to fine tune the handler's configuration. In that case, the call to RegisterGCSHandler() should be done before the call to RegisterAll() to prevent the plugin from registering the gs:// prefix.
• Authentication is handled entirely by the cloud.google.com/go/storage SDK, which should be transparent on any GCP compute instance. If running outside of GCP, you should launch gcloud auth application-default login to setup your credentials.

Building

From this directory, run make && sudo make install . If the installation cannot be performed automatically, manually copy gdal_gcs.so to your $(GDAL_INSTALL_PREFIX)/lib/gdalplugins folder.