Allow created containers to be killed

[mrunalp]

Signed-off-by: Mrunal Patel [email protected]

[crosbymichael]

LGTM

[wking]

I'd rather tie this more clearly to the already-well-defined state values. Something like:

Attempting to send a signal to a container that is neither [`created` nor `running`](#state) MUST have no effect…

That's pretty close to what you're suggesting, although it:

• Uses “neither”/“nor” instead of repeating “not”.
• Links to the “State” section for formal definitions of created and running states.
• Uses backticks to strengthen the “these are formally defined terms” semantics of running and created.
• Lists created before running, since any given container that ends up in running will always have passed through created earlier in its lifecycle, and no container can return to created after it has entered running.

[dqminh]

LGMT with @wking's suggestion,

[tianon]

What's the use-case for killing a container that isn't running? What's the expected behavior?

[wking]

What's the use-case for killing a container that isn't running?

Getting ready to delete a container that you hadn't started. More on containers not getting started in #701.

What's the expected behavior?

The signal gets sent to the container process, same as in the running case. The container process will still be running a runtime-supplied program, but that doesn't effect sending signals to it.

[wking]

While we're cleaning up the relationship between operations and container state, I think we can replace these two start lines with:

Attempting to `start` a container that is not [`created`](#state) MUST have no effect on the container and MUST [generate an error](#errors).

And these two delete lines with:

Attempting to `delete` a container that is not [`stopped`](#state) MUST have no effect on the container and MUST [generate an error](#errors).

[mrunalp]

Updated.

[tianon]

LGTM

[mrunalp]

@tianon Orchestrator could have a sequence where it is first creating a bunch of containers and then starting them. If there is a failure in the start sequence it could just kill the remaining created containers.

[crosbymichael]

LGTM