Downloading XLSX sometimes has large column gaps

[longhotsummer]

Downloading some wide XLSX data sometimes produces large empty columns. This seems to be an issue with the gdal library we're using to build the XLSX.

[longhotsummer]

It looks like this was fixed in GDAL 1.11 at some point a while back, I'm not sure why we're still seeing it.

https://trac.osgeo.org/gdal/ticket/5774

[longhotsummer]

I can confirm it still happens with GDAL 1.11.1, perhaps 1.11.2 fixed it.

[longhotsummer]

I think we should explore upgrading to GDAL 2.x, taking into account common GDAL versions on Ubuntu (14.04 and 16.04).

[longhotsummer]

Ubuntu 14.04 LTS (Trusty Tar) gets 1.10 by default, which is actually too old for Wazimap in any case, and we have to pull the 1.11 version from a separate repo.

Ubuntu 16.04 LTS has 1.11.3 which should be suitable.

So sticking with >1.11.1 and <2.0 seems reasonable for now.

https://launchpad.net/ubuntu/+source/gdal

[longhotsummer]

The buildpack we use to pull in this dependency in production (dokku, heroku) is fixed at 1.11.1 for the heroku/dokku ceder-14 stack: https://github.com/cyberdelia/heroku-geo-buildpack

$ curl http://cyberdelia-geo-buildpack.s3.amazonaws.com/cedar-14/manifest.gdal
1.11.1

[longhotsummer]

Opened cyberdelia/heroku-geo-buildpack#42

[longhotsummer]

Another alternative is to write our own Excel files, that's pretty straight forward.

[longhotsummer]

We may be able to use the Apt buildpack from heroku to pull in exactly the gdal we want. https://elements.heroku.com/buildpacks/heroku/heroku-buildpack-apt