Spot instantiation, run_task command and creation failure policies.

[ArturRSoda]

Implementation of spot instantiation.

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Initial implementation of run_task command.

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Implementation of three policies in instances creation failure:

• Cancel:

  • If any instance fails to launch, terminate the whole cluster, clean up all resources, and return the error.

  • Terminal on failure to instantiate instances with cancel policy:

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• On-demand:

  • If any instance fails to launch, terminate the whole cluster, cleaning up all resources, and try calling again the spawn function changing the allocation mode of the failed node to 'on-demand'.

  • Terminal on failure to instantiate instances with on-demand policy:

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• Migrate:

  • If any instance fails to launch, terminate the whole cluster, cleaning up all resources, and try calling again the spawn function with a new cluster configuration with the next availability-zone.

  • The application tries to migrate for MAX_MIGRATION_ATTEMPTS, if all the attempts fail, it just returns the error.

  • Terminal on failure to instantiate instances with migrate policy:

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