Tools like `nomad-nodesim` are unable to implement a minimal implementation of
an allocrunner so that we can test the client communication without having to
lug around the entire allocrunner/taskrunner code base. The allocrunner was
implemented with an interface specifically for this purpose, but there were
circular imports that made it challenging to use in practice.
Move the AllocRunner interface into an inner package and provide a factory
function type. Provide a minimal test that exercises the new function so that
consumers have some idea of what the minimum implementation required is.
* client: run alloc pre-kill hooks on last pass despite no live tasks
This PR fixes a bug where alloc pre-kill hooks were not run in the
edge case where there are no live tasks remaining, but it is also
the final update to process for the (terminal) allocation. We need
to run cleanup hooks here, otherwise they will not run until the
allocation gets garbage collected (i.e. via Destroy()), possibly
at a distant time in the future.
Fixes#15477
* client: do not run ar cleanup hooks if client is shutting down
* allocrunner: handle lifecycle when all tasks die
When all tasks die the Coordinator must transition to its terminal
state, coordinatorStatePoststop, to unblock poststop tasks. Since this
could happen at any time (for example, a prestart task dies), all states
must be able to transition to this terminal state.
* allocrunner: implement different alloc restarts
Add a new alloc restart mode where all tasks are restarted, even if they
have already exited. Also unifies the alloc restart logic to use the
implementation that restarts tasks concurrently and ignores
ErrTaskNotRunning errors since those are expected when restarting the
allocation.
* allocrunner: allow tasks to run again
Prevent the task runner Run() method from exiting to allow a dead task
to run again. When the task runner is signaled to restart, the function
will jump back to the MAIN loop and run it again.
The task runner determines if a task needs to run again based on two new
task events that were added to differentiate between a request to
restart a specific task, the tasks that are currently running, or all
tasks that have already run.
* api/cli: add support for all tasks alloc restart
Implement the new -all-tasks alloc restart CLI flag and its API
counterpar, AllTasks. The client endpoint calls the appropriate restart
method from the allocrunner depending on the restart parameters used.
* test: fix tasklifecycle Coordinator test
* allocrunner: kill taskrunners if all tasks are dead
When all non-poststop tasks are dead we need to kill the taskrunners so
we don't leak their goroutines, which are blocked in the alloc restart
loop. This also ensures the allocrunner exits on its own.
* taskrunner: fix tests that waited on WaitCh
Now that "dead" tasks may run again, the taskrunner Run() method will
not return when the task finishes running, so tests must wait for the
task state to be "dead" instead of using the WaitCh, since it won't be
closed until the taskrunner is killed.
* tests: add tests for all tasks alloc restart
* changelog: add entry for #14127
* taskrunner: fix restore logic.
The first implementation of the task runner restore process relied on
server data (`tr.Alloc().TerminalStatus()`) which may not be available
to the client at the time of restore.
It also had the incorrect code path. When restoring a dead task the
driver handle always needs to be clear cleanly using `clearDriverHandle`
otherwise, after exiting the MAIN loop, the task may be killed by
`tr.handleKill`.
The fix is to store the state of the Run() loop in the task runner local
client state: if the task runner ever exits this loop cleanly (not with
a shutdown) it will never be able to run again. So if the Run() loops
starts with this local state flag set, it must exit early.
This local state flag is also being checked on task restart requests. If
the task is "dead" and its Run() loop is not active it will never be
able to run again.
* address code review requests
* apply more code review changes
* taskrunner: add different Restart modes
Using the task event to differentiate between the allocrunner restart
methods proved to be confusing for developers to understand how it all
worked.
So instead of relying on the event type, this commit separated the logic
of restarting an taskRunner into two methods:
- `Restart` will retain the current behaviour and only will only restart
the task if it's currently running.
- `ForceRestart` is the new method where a `dead` task is allowed to
restart if its `Run()` method is still active. Callers will need to
restart the allocRunner taskCoordinator to make sure it will allow the
task to run again.
* minor fixes
This commit performs refactoring to pull out common service
registration objects into a new `client/serviceregistration`
package. This new package will form the base point for all
client specific service registration functionality.
The Consul specific implementation is not moved as it also
includes non-service registration implementations; this reduces
the blast radius of the changes as well.
In certain task lifecycles the taskrunner service deregister call
could be called three times for a task that is exiting. Whilst
each hook caller of deregister has its own purpose, we should try
and ensure it is only called once during the shutdown lifecycle of
a task.
This change therefore tracks when deregister has been called, so
that subsequent calls are noop. In the event the task is
restarting, the deregister value is reset to ensure proper
operation.
There are bits of logic in callers of RemoveWorkload on group/task
cleanup hooks which call RemoveWorkload with the "Canary" version
of the workload, in case the alloc is marked as a Canary. This logic
triggers an extra sync with Consul, and also doesn't do the intended
behavior - for which no special casing is necessary anyway. When the
workload is marked for removal, all associated services and checks
will be removed regardless of the Canary status, because the service
and check IDs do not incorporate the canary-ness in the first place.
The only place where canary-ness matters is when updating a workload,
where we need to compute the hash of the services and checks to determine
whether they have been modified, the Canary flag of which is a part of
that.
Fixes#10842
* client: improve group service stanza interpolation and check_restart support
Interpolation can now be done on group service stanzas. Note that some task runtime specific information
that was previously available when the service was registered poststart of a task is no longer available.
The check_restart stanza for checks defined on group services will now properly restart the allocation upon
check failures if configured.
When an alloc runner prestart hook fails, the task runners aren't invoked
and they remain in a pending state.
This leads to terrible results, some of which are:
* Lockup in GC process as reported in https://github.com/hashicorp/nomad/pull/5861
* Lockup in shutdown process as TR.Shutdown() waits for WaitCh to be closed
* Alloc not being restarted/rescheduled to another node (as it's still in
pending state)
* Unexpected restart of alloc on a client restart, potentially days/weeks after
alloc expected start time!
Here, we treat all tasks to have failed if alloc runner prestart hook fails.
This fixes the lockups, and permits the alloc to be rescheduled on another node.
While it's desirable to retry alloc runner in such failures, I opted to treat it
out of scope. I'm afraid of some subtles about alloc and task runners and their
idempotency that's better handled in a follow up PR.
This might be one of the root causes for
https://github.com/hashicorp/nomad/issues/5840 .
This change fixes a bug where nomad would avoid running alloc tasks if
the alloc is client terminal but the server copy on the client isn't
marked as running.
Here, we fix the case by having task runner uses the
allocRunner.shouldRun() instead of only checking the server updated
alloc.
Here, we preserve much of the invariants such that `tr.Run()` is always
run, and don't change the overall alloc runner and task runner
lifecycles.
Fixes https://github.com/hashicorp/nomad/issues/5883
We currently only run cleanup Service Hooks when a task is either
Killed, or Exited. However, due to the implementation of a task runner,
tasks are only Exited if they every correctly started running, which is
not true when you recieve an error early in the task start flow, such as
not being able to pull secrets from Vault.
This updates the service hook to also call consul deregistration
routines during a task Stop lifecycle event, to ensure that any
registered checks and services are cleared in such cases.
fixes#5770
Builds upon earlier commit that cleans up restored handles of terminal
allocs by also emitting terminated events and calling exited hooks when
appropriate.
The test is sadly quite complicated and peeks into things (logmon's
reattach config) AR doesn't normally have access to.
However, I couldn't find another way of asserting logmon got cleaned up
without resorting to smaller unit tests. Smaller unit tests risk
re-implementing dependencies in an unrealistic way, so I opted for an
ugly integration test.
Tim Gross