scheduler: fix dropped test error

client: track service deregister call so it's only called once.

The `volume detach`, `volume deregister`, and `volume status` commands
accept a prefix argument for the volume ID. Update the behavior on
exact matches so that if there is more than one volume that matches
the prefix, we should only return an error if one of the volume IDs is
not an exact match. Otherwise we won't be able to use these commands
at all on those volumes. This also makes the behavior of these commands
consistent with `job stop`.

The CSI specification says:
> The CO SHALL provide the listen-address for the Plugin by way of the
`CSI_ENDPOINT` environment variable.

Note that plugins without filesystem isolation won't have the plugin
dir bind-mounted to their alloc dir, but we can provide a path to the
socket anyways.

Refactor to use opts struct for plugin supervisor hook config.
The parameter list for configuring the plugin supervisor hook has
grown enough where is makes sense to use an options struct similiar to
many of the other task runner hooks (ex. template).

doc(typo): technical typo in advertised example

changelog: add entry for #12040

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.

The allocReconciler's computeGroup function contained a significant amount of inline logic that was difficult to understand the intent of. This commit extracts inline logic into the following intention revealing subroutines. It also includes updates to the function internals also aimed at improving maintainability and renames some existing functions for the same purpose. New or renamed functions include.

Renamed functions

- handleGroupCanaries -> cancelUnneededCanaries
- handleDelayedLost -> createLostLaterEvals
- handeDelayedReschedules -> createRescheduleLaterEvals

New functions

- filterAndStopAll
- initializeDeploymentState
- requiresCanaries
- computeCanaries
- computeUnderProvisionedBy
- computeReplacements
- computeDestructiveUpdates
- computeMigrations
- createDeployment
- isDeploymentComplete

Merge release 1.2.6 branch

Version 1.2.6

The spread iterator can panic when processing an evaluation, resulting
in an unrecoverable state in the cluster. Whenever a panicked server
restarts and quorum is restored, the next server to dequeue the
evaluation will panic.

To trigger this state:
* The job must have `max_parallel = 0` and a `canary >= 1`.
* The job must not have a `spread` block.
* The job must have a previous version.
* The previous version must have a `spread` block and at least one
  failed allocation.

In this scenario, the desired changes include `(place 1+) (stop
1+), (ignore n) (canary 1)`. Before the scheduler can place the canary
allocation, it tries to find out which allocations can be
stopped. This passes back through the stack so that we can determine
previous-node penalties, etc. We call `SetJob` on the stack with the
previous version of the job, which will include assessing the `spread`
block (even though the results are unused). The task group spread info
state from that pass through the spread iterator is not reset when we
call `SetJob` again. When the new job version iterates over the
`groupPropertySets`, it will get an empty `spreadAttributeMap`,
resulting in an unexpected nil pointer dereference.

This changeset resets the spread iterator internal state when setting
the job, logging with a bypass around the bug in case we hit similar
cases, and a test that panics the scheduler without the patch.

Add new namespace ACL requirement for the /v1/jobs/parse endpoint and
return early if HCLv2 parsing fails.

The endpoint now requires the new `parse-job` ACL capability or
`submit-job`.

This PR adds symlink resolution when doing validation of paths
to ensure they do not escape client allocation directories.

go-getter creates a circular dependency between a Client and Getter,
which means each is inherently thread-unsafe if you try to re-use
on or the other.

This PR fixes Nomad to no longer make use of the default Getter objects
provided by the go-getter package. Nomad must create a new Client object
on every artifact download, as the Client object controls the Src and Dst
among other things. When Caling Client.Get, the Getter modifies its own
Client reference, creating the circular reference and race condition.

We can still achieve most of the desired connection caching behavior by
re-using a shared HTTP client with transport pooling enabled.

When an allocation is updated, the job summary for the associated job
is also updated. CSI uses the job summary to set the expected count
for controller and node plugins. We incorrectly used the allocation's
server status instead of the job status when deciding whether to
update or remove the job from the plugins. This caused a node drain or
other terminal state for an allocation to clear the expected count for
the entire plugin.

Use the job status to guide whether to update or remove the expected
count.

The existing CSI tests for the state store incorrectly modeled the
updates we received from servers vs those we received from clients,
leading to test assertions that passed when they should not.

Rework the tests to clarify each step in the lifecycle and rename CSI state
store functions for clarity

env: update aws cpu configs

By running the tools/ec2info tool

Processing an evaluation is nearly a pure function over the state
snapshot, but we randomly shuffle the nodes. This means that
developers can't take a given state snapshot and pass an evaluation
through it and be guaranteed the same plan results.

But the evaluation ID is already random, so if we use this as the seed
for shuffling the nodes we can greatly reduce the sources of
non-determinism. Unfortunately golang map iteration uses a global
source of randomness and not a goroutine-local one, but arguably
if the scheduler behavior is impacted by this, that's a bug in the
iteration.

changelog: update changelog for DO

Co-authored-by: Luiz Aoqui <luiz@hashicorp.com>

client/fingerprint: add digitalocean fingerprinter

website: display warning in IE 11

Co-authored-by: Seth Hoenig <seth.a.hoenig@gmail.com>

If processing a specific evaluation causes the scheduler (and
therefore the entire server) to panic, that evaluation will never
get a chance to be nack'd and cleared from the state store. It will
get dequeued by another scheduler, causing that server to panic, and
so forth until all servers are in a panic loop. This prevents the
operator from intervening to remove the evaluation or update the
state.

Recover the goroutine from the top-level `Process` methods for each
scheduler so that this condition can be detected without panicking the
server process. This will lead to a loop of recovering the scheduler
goroutine until the eval can be removed or nack'd, but that's much
better than taking a downtime.