Heat Convergence Prototype

This is a simple prototype to help prove the concepts behind the proposed new "Convergence" architecture for OpenStack Heat.

It uses a trivial in-memory datastore and an event loop within a single process to simulate multiple processes with asynchronous message passing. Note that it cannot simulate race conditions or other concurrency errors, since only one event is ever processed at a time.

Debugging

Run the code by typing python -m converge. Note that when run directly like this, the test assertions in the scenarios are ignored (a warning is logged). This mode is useful for debugging and becoming familiar with the code because it displays all of the log messages that allow you to follow the execution.

Usage: /usr/bin/python -m converge [options] SCENARIOS

 An OpenStack Heat convergence algorithm simulator.

Options:
  -h, --help            show this help message and exit
  -d DIR, --scenario-directory=DIR
                        Directory to read scenarios from
  -p, --pdb             Enable debugging with pdb

To run a specific subset of the test scenarios, append their names to the command line (e.g. python -m converge basic_create).

To automatically set debugger breakpoints at the beginning of each asynchronous task, pass the --pdb option on the command line.

Verification

The unit tests can also be used to not only run the scenarios but verify the correctness of the results. To do this, run:

python -m unittest test_converge

You can also use some other testrunners, including and maybe not even limited to Nose:

nosetests test_converge