This is two lines of thought combined into one merge:

1. AMQP clients should either receive messages or send messages
2. Capability queues are based on a database-backed queue manager rather than keeping state in-memory

Most of the work relating to the first idea comes in refactoring the Router to not be a message sender. Many places in the code now either instantiate a MessageSender instead, or use both a Router and a MessageSender if they truly needed both functionalities. The previous implementation appears to have caused messages to arrive out of order because facilities like `wf_monitor` that only send messages were also trying to receive messages, and either not handling them at all or putting them into a buffer of some kind to be dropped on the floor when the process ended.

The work relating to the second idea changes the way that steps are processed in the capability service and eliminates the capability engine concept. Now when PrepareAndRunWorkflow steps are reached, the capability is simply moved into the Waiting state and the queue manager is signaled. Whenever the queue manager is awakened, it checks to see if any queues have slots available and requests waiting. If they do, the number of available slots are used to get requests and start executing them. When an execution exits the cluster, the queue manager is signaled again, so the process continues until all the jobs are processed. As a stability benefit, we check this on startup as well.

old name    new name
---         ---
ready       created
executing   submitted
?           in_progress

removed EXPOSE cmd in frontend's Dockerfile.dev and added empty dependencies to CI stages that don't need artifacts for efficiency

Daniel Lyons authored 4 years ago and Nathan Hertz committed 4 years ago

Added the ability to compare capability executions by their creation timestamp; made it so encountering exceptions when receiving messages does not block the system

Charlotte Hausman authored 4 years ago and Nathan Hertz committed 4 years ago

Messaging system is now running on a more robust foundation:
- `kombu` package for AMQP networking
- New Messenger and Router objects
- New message format
- Easy-to-use callback subscribing
- Can now get messages anywhere in the system easily and send replies back easily

Nathan Hertz authored 4 years ago and Nathan Hertz committed 4 years ago

existing executions cannot be deleted (they must be disabled instead,
which will have to be implemented)

Refactored execution management logic out of `CapabilityService` into a new class `ExecutionManager`

`CapabilityService.create_request` instead of duplicating that logic
within the view; changed tests and mocks to go along with the changes

forgot to add in the previous MR

Added two new Pyramid views, the first of the capability request views: `view_capability_request` and `create_capability_request`

added views directory that will hold logic for views

null.cap with arguments

object and create a request from there

conflicts and circular imports

helper.py; added from_string constructor to CapabilityStepType