When we introduced change_mode=script to templates, we passed the driver handle
down into the template manager so we could call its `Exec` method directly. But
the lifecycle of the driver handle is managed by the taskrunner and isn't
available when the template manager is first created. This has led to a series
of patches trying to fixup the behavior (#15915, #15192, #23663, #23917). Part
of the challenge in getting this right is using an interface to avoid the
circular import of the driver handle.
But the taskrunner already has a way to deal with this problem using a "lazy
handle". The other template change modes already use this indirectly through the
`Lifecycle` interface. Change the driver handle `Exec` call in the template
manager to a new `Lifecycle.Exec` call that reuses the existing behavior. This
eliminates the need for the template manager to know anything at all about the
handle state.
Fixes: https://github.com/hashicorp/nomad/issues/24051
* build: update to go1.21
* go: eliminate helpers in favor of min/max
* build: run go mod tidy
* build: swap depguard for semgrep
* command: fixup broken tls error check on go1.21
This PR fixes a bug where client configuration max_kill_timeout was
not being enforced. The feature was introduced in 9f44780 but seems
to have been removed during the major drivers refactoring.
We can make sure the value is enforced by pluming it through the DriverHandler,
which now uses the lesser of the task.killTimeout or client.maxKillTimeout.
Also updates Event.SetKillTimeout to require both the task.killTimeout and
client.maxKillTimeout so that we don't make the mistake of using the wrong
value - as it was being given only the task.killTimeout before.
Add a new driver capability: RemoteTasks.
When a task is run by a driver with RemoteTasks set, its TaskHandle will
be propagated to the server in its allocation's TaskState. If the task
is replaced due to a down node or draining, its TaskHandle will be
propagated to its replacement allocation.
This allows tasks to be scheduled in remote systems whose lifecycles are
disconnected from the Nomad node's lifecycle.
See https://github.com/hashicorp/nomad-driver-ecs for an example ECS
remote task driver.
plugins/driver: update driver interface to support streaming stats
client/tr: use streaming stats api
TODO:
* how to handle errors and closed channel during stats streaming
* prevent tight loop if Stats(ctx) returns an error
drivers: update drivers TaskStats RPC to handle streaming results
executor: better error handling in stats rpc
docker: better control and error handling of stats rpc
driver: allow stats to return a recoverable error
