Databricks

The docker images described below are maintained by Databricks. Please direct questions about them to Databricks.

Hail can be installed on a Databricks Spark cluster on Microsoft Azure, Amazon Web Services, or Google Cloud Platform via an open source Docker container located in the Project Glow Dockerhub. Docker files to build your own Hail container on Databricks can be found in the Glow Github repository.

Install Hail via Docker with Databricks Container Services.

Use the Docker Image URL, projectglow/databricks-hail:<hail_version>, replacing the tag with an available Hail version. Please match the Databricks Runtime Spark version to the Spark version Hail is built with.

Use Hail in a notebook

For the most part, Hail in Databricks works identically to the Hail documentation. However, there are a few modifications that are necessary for the Databricks environment.

Initialize Hail

When initializing Hail, pass in the pre-created SparkContext and mark the initialization as idempotent. This setting enables multiple Databricks notebooks to use the same Hail context.

note
  • Enable skip_logging_configuration to save logs to the rolling driver log4j output. This setting is supported only in Hail 0.2.39 and above.

  • Hail is not supported with Credential passthrough.

code
>>> import hail as hl
>>> hl.init(sc, idempotent=True, quiet=True, skip_logging_configuration=True)  

Display Bokeh plots

Hail uses the Bokeh library to create plots. The show function built into Bokeh does not work in Databricks. To display a Bokeh plot generated by Hail, you can run a command like:

>>> from bokeh.embed import components, file_html
>>> from bokeh.resources import CDN
>>> plot = hl.plot.histogram(mt.DP, range=(0,30), bins=30, title='DP Histogram', legend='DP')
>>> html = file_html(plot, CDN, "Chart")

And then call the Databricks function displayHTML with html as its argument.

See Databricks’ Bokeh docs for more information.