boots should not PXE if no workflow defined

[nathangoulding]

If there is no active workflow for a worker, boots should not PXE boot a system. Right now, it will always PXE into the environment and noop, which is not a practical use case.

[rgl]

Instead of being a noop I would like to be able to specify a workflow for the machines that do not (yet) have a workflow. That way I can deal with them (e.g. run some kind of inventory application on them and show the machine in some kind of "un-provisioned/new" machines catalog).

[nathangoulding]

@rgl Agreed this would be a good capability to create a default "wait-for-work" template + container that comes baked with Tinkerbell. We also need this in Packet, and I think would have broad appeal. Perhaps we can capture that in a separate issue.

[Cbkhare]

Updates so far.

-) Development & Testing activity:

1. Changes to fetch worker id for given hardware. Dev + test (Done)

2. Changes to fetch workflow for a given worker id. Dev - (Done) + Test in progress.

3. Point 2 requires addition of a rpc client to fetch workflow, changes is required in both boots and tink. Actually, I was using existing client to fetch workflow and after i got go panic error i found, rpc client is currently specific to hardware clis. So, i added a rpc client for workflow. Dev (Done) + Boots Test (Done) + Tink in progress.

4. Endpoints to fetch workflow using client. Dev (Done) + Test, in progress, currently fixing client in point3.

5. Using above workflow client, i can fetch workflows and filter which are active. Once, my testing on clients and endpoints are completed i will complete this. Dev + Test (in progress)

I have raised below PR, for workflow client changes in boots and tink. Later, i will add my other changes in same branch.

96bb35d
tinkerbell/tink@f14f070

[Cbkhare]

Tested this PR along with tinkerbell/tink#200.

• Testing with Active workflow :- completed

{"level":"info","ts":1593695857.2480636,"caller":"job/job.go:55","msg":"found active workflow for hardware 0eba0bf8-3772-4b4a-ab9f-6ebe93b90a94 with workflow id d0f730bc-894d-42de-8c37-9e423f5c761d","service":"github.com/tinkerbell/boots","pkg":"http","dhcp":"0eba0bf8-3772-4b4a-ab9f-6ebe93b90a94"}

• Testing without active workflow:-completed

{"level":"info","ts":1593696050.6527524,"caller":"boots/dhcp.go:76","msg":"retrieved job is empty","service":"github.com/tinkerbell/boots","pkg":"main","type":"DHCPDISCOVER","mac":"08:00:27:00:00:01","err":"No active workflow found for hardware 0eba0bf8-3772-4b4a-ab9f-6ebe93b90a94"}