Read file from bucketfs inside a UDF from `/buckets`

[tkilias]

Background

• The BucketFS is in Exasol mounted as read only filesystem on each node
• It is faster to read files in the BucketFS from the filesystem as downloading them via HTTP

Acceptance Criteria

• Read a file from the BucketFS via the file system given a Bucket Object and a file path
• Targets are String, FileObj, to file, to object via joblib

[tkilias]

• Add new file similar to download.py with similar functions but these function read from udf file system. Maybe name it like load_from_udf_fs_...
• Add these functions as well to the BucketFSLocation

[tkilias]

Regarding testing

• We need a project-specific language container
• You can find the mechanism to build the container here:
  • https://github.com/exasol/data-science-utils-python/tree/main/language_container
  • https://github.com/exasol/data-science-utils-python/blob/main/build_language_container.sh
  • You need to rename the flavor
  • And change the language alias in https://github.com/exasol/data-science-utils-python/blob/main/language_container/exasol-data-science-utils-python-container/flavor_base/language_definition
• To include the container into your tests you need:
  • https://github.com/exasol/data-science-utils-python/tree/main/tests/integration_tests/fixtures
  • https://github.com/exasol/data-science-utils-python/blob/main/tests/conftest.py
  • https://github.com/exasol/data-science-utils-python/blob/7d1e6f6b69c10a67ac38e4dd5c57d16670ca6026/tests/integration_tests/test_train_udf.py#L30
  • The language