Support for Google Cloud Storage

[perlman]

This is a small experiment for writing output directly to GCS.

This is done by including google-cloud-nio. outputOptions needs to be non-null for newFileSystem().

While functional, this is still incomplete:

• values in outputOptions need to be coerced into Integer/Boolean/etc to work with java-storage-nio.
• some mechanism for specifying alternate credentials (link to google docs for credentials)
• Add test using com.google.cloud.storage.contrib.nio.testing

(As a side note, we tried using Google's S3 interface. It fails on a permissions check in JZarr before writing data.)

[melissalinkert]

@perlman: did you have more work planned here?

[perlman]

I've been using this unmodified for a while now. I'll bring it up-to-date with main and see where we're at.

[melissalinkert]

Thanks for the update, @perlman. I'm fine with taking this out of draft status, but adding a usage example to the README would be helpful for testing.

[melissalinkert]

@perlman, is there a simple example of how to use this feature?

[perlman]

Whoops, I let this slip. I'll get to this today or tomorrow! (or Monday, sorry about that.)

[perlman]

@melissalinkert I'm wondering where the right place to put an example. I had started to modify the --help text, but it seems that it may be a bit too verbose?

The usage is very straight forward, e.g.:

bioformats2raw-0.7.1-SNAPSHOT/bin/bioformats2raw --tile_width 2048 A_2202_20_ApoB.ndpi gs://jax-zarr-playpen/data/A_2202_20_ApoB.zarr

That's it. The access credentials will come from the environment, e.g, gcloud auth login or inherited from a service account. (Application Default Credentials )

The credentials must allow for read/write on the bucket. (Minimally, this can be Storage Object Creator, Storage Object Viewer and Storage Object Delete).

--output-options does not currently work. Google NIO does not seem happy with the Map<string, string>, with an exception related to the type. I've punted temporarily on digging into this, as it would probably require some special case type conversion of the values.

[melissalinkert]

Sorry for dropping this - really was just thinking a few lines in the README.md with exactly what you've already noted in #176 (comment) is sufficient documentation.

[melissalinkert]

@perlman: that's great, thanks. Do you want to take this out of draft so we can consider for 0.8.0? Or did you have more work planned before this is ready for review?

[perlman]

I think this meets MVP! I've been using it to convert a bunch of NDPI files to Zarr.

At minimum, I think we should add an example of using s3 to the README (& the suggested flags used for Cloudian deployments).

"Nice to have" would be working flags for GCS (which require correct value types) and a test using com.google.cloud.storage.contrib.nio.testing, which would show functional NIO2 integration.