Arvados

• Container is expected/intended to be impure (results differ from one run to the next)
• Test/diagnostics container

The Containers API specifies a "filters" parameter which (when implemented) could be used to achieve this with something like filters=[[created_at,=,now]].

Implementation:

• Add a 'use_existing' flag, which defaults to true. When set false a new container should always be created.
• Add '"use_existing": false, ' to the 'Hello, Crunch' example at http://doc.arvados.org/install/crunch2-slurm/install-test.html

As for the future "filters" parameter, if/when that gets implemented, the 'use_existing' flag should take precedence if set to false.