The AllocUpdateRequest struct is used in three disjoint use cases:

1. Stripped allocs from clients Node.UpdateAlloc RPC using the Allocs,
   and WriteRequest fields
2. Raft log message using the Allocs, Evals, and WriteRequest fields
3. Plan updates using the AllocsStopped, AllocsUpdated, and Job fields

Adding a new field that would only be used in one these cases (1) made
things more confusing and error prone. While in theory an
AllocUpdateRequest could send allocations from different nodes, in
practice this never actually happens since only clients call this method
with their own allocations.

Reconnected allocs have a new AllocState entry that must be persisted by
the plan applier.

When the client reconnects with the server it synchronizes the state of
its allocations by sending data using the `Node.UpdateAlloc` RPC and
fetching data using the `Node.GetClientAllocs` RPC.

If the data fetch happens before the data write, `unknown` allocations
will still be in this state and would trigger the
`allocRunner.Reconnect` flow.

But when the server `DesiredStatus` for the allocation is `stop` the
client should not reconnect the allocation.

Clients interact with servers using three main RPC methods:

  - `Node.GetAllocs` reads allocation data from the server and writes it
    to the client.
  - `Node.UpdateAlloc` reads allocation from from the client and writes
    them to the server.
  - `Node.UpdateStatus` writes the client status to the server and is
    used as the heartbeat mechanism.

These three methods are called periodically by the clients and are done
so independently from each other, meaning that there can't be any
assumptions in their ordering.

This can generate scenarios that are hard to reason about and to code
for. For example, when a client misses too many heartbeats it will be
considered `down` or `disconnected` and the allocations it was running
are set to `lost` or `unknown`.

When connectivity is restored the to rest of the cluster, the natural
mental model is to think that the client will heartbeat first and then
update its allocations status into the servers.

But since there's no inherit order in these calls the reverse is just as
possible: the client updates the alloc status and then heartbeats. This
results in a state where allocs are, for example, `running` while the
client is still `disconnected`.

This commit adds a new verification to the `Node.UpdateAlloc` method to
reject updates from nodes that are not `ready`, forcing clients to
heartbeat first. Since this check is done server-side there is no need
to coordinate operations client-side: they can continue sending these
requests independently and alloc update will succeed after the heartbeat
is done.

When a client reconnects it makes two independent RPC calls:

  - `Node.UpdateStatus` to heartbeat and set its status as `ready`.
  - `Node.UpdateAlloc` to update the status of its allocations.

These two calls can happen in any order, and in case the allocations are
updated before a heartbeat it causes the state to be the same as a node
being disconnected: the node status will still be `disconnected` while
the allocation `ClientStatus` is set to `running`.

The current implementation did not handle this order of events properly,
and the scheduler would create an unnecessary placement since it
considered the allocation was being disconnected. This extra allocation
would then be quickly stopped by the heartbeat eval.

This commit adds a new code path to handle this order of events. If the
node is `disconnected` and the allocation `ClientStatus` is `running`
the scheduler will check if the allocation is actually reconnecting
using its `AllocState` events.

When an allocation reconnects to a cluster the scheduler needs to run
special logic to handle the reconnection, check if a replacement was
create and stop one of them.

If the allocation kept running while the node was disconnected, it will
be reconnected with `ClientStatus: running` and the node will have
`Status: ready`. This combination is the same as the normal steady state
of allocation, where everything is running as expected.

In order to differentiate between the two states (an allocation that is
reconnecting and one that is just running) the scheduler needs an extra
piece of state.

The current implementation uses the presence of a
`TaskClientReconnected` task event to detect when the allocation has
reconnected and thus must go through the reconnection process. But this
event remains even after the allocation is reconnected, causing all
future evals to consider the allocation as still reconnecting.

This commit changes the reconnect logic to use an `AllocState` to
register when the allocation was reconnected. This provides the
following benefits:

  - Only a limited number of task states are kept, and they are used for
    many other events. It's possible that, upon reconnecting, several
    actions are triggered that could cause the `TaskClientReconnected`
    event to be dropped.
  - Task events are set by clients and so their timestamps are subject
    to time skew from servers. This prevents using time to determine if
    an allocation reconnected after a disconnect event.
  - Disconnect events are already stored as `AllocState` and so storing
    reconnects there as well makes it the only source of information
    required.

With the new logic, the reconnection logic is only triggered if the
last `AllocState` is a disconnect event, meaning that the allocation has
not been reconnected yet. After the reconnection is handled, the new
`ClientStatus` is store in `AllocState` allowing future evals to skip
the reconnection logic.

The existing docs on required capabilities are a little sparse and have been the
subject of a lots of questions. Expand on this information and provide a pointer
to the ongoing design discussion around rootless Nomad.

* client: ensure minimal cgroup controllers enabled

This PR fixes a bug where Nomad could not operate properly on operating
systems that set the root cgroup.subtree_control to a set of controllers that
do not include the minimal set of controllers needed by Nomad.

Nomad needs these controllers enabled to operate:
- cpuset
- cpu
- io
- memory
- pids

Now, Nomad will ensure these controllers are enabled during Client initialization,
adding them to cgroup.subtree_control as necessary. This should be particularly
helpful on the RHEL/CentOS/Fedora family of system. Ubuntu systems should be
unaffected as they enable all controllers by default.

Fixes: https://github.com/hashicorp/nomad/issues/14494

* docs: cleanup doc string

* client: cleanup controller writes, enhance log messages

Follow-up from https://github.com/hashicorp/nomad/pull/14987/files#r1003611644

We don't need to hold the lock when querying the state store, so move the
read-lock to the interior of the `activeKeySet` function.

* deps: update hashicorp/raft to v1.3.11

Includes part of the fix for https://github.com/hashicorp/raft/issues/524

* cl: add changelog entry

Forgot to add this line to the new mods action; without it, it
creates a cache different from the one used by the other jobs.

The configuration knobs for root keyring garbage collection are present in the
consumer and present in the user-facing config, but we missed the spot where we
copy from one to the other. Fix this so that users can set their own thresholds.

The root key is automatically rotated every ~30d, but the function that does
both rotation and key GC was wired up such that `nomad system gc` caused an
unexpected key rotation. Split this into two functions so that `nomad system gc`
cleans up old keys without forcing a rotation, which will be done periodially
or by the `nomad operator root keyring rotate` command.

* ci: use the same go mod cache for test-core jobs

* ci: precache go modules

* ci: add a mods precache job

* keyring: don't unblock early if rate limit burst exceeded

The rate limiter returns an error and unblocks early if its burst limit is
exceeded (unless the burst limit is Inf). Ensure we're not unblocking early,
otherwise we'll only slow down the cases where we're already pausing to make
external RPC requests.

* keyring: set MinQueryIndex on stale queries

When keyring replication makes a stale query to non-leader peers to find a key
the leader doesn't have, we need to make sure the peer we're querying has had a
chance to catch up to the most current index for that key. Otherwise it's
possible for newly-added servers to query another newly-added server and get a
non-error nil response for that key ID.

Ensure that we're setting the correct reply index in the blocking query.

Note that the "not found" case does not return an error, just an empty key. So
as a belt-and-suspenders, update the handling of empty responses so tha...

Originally this test relied on Job 1 blocking Job 2 until Job 1 had a
terminal *ClientStatus.* Job 2 ensured it would get blocked using 2
mechanisms:

1. A constraint requiring it is placed on the same node as Job 1.
2. Job 2 would require all unreserved CPU on the node to ensure it would
   be blocked until Job 1's resources were free.

That 2nd assertion breaks if *any previous job is still running on the
target node!* That seems very likely to happen in the flaky world of our
e2e tests. In fact there may be some jobs we intentionally want running
throughout; in hindsight it was never safe to assume my test would be
the only thing scheduled when it ran.

*Ports to the rescue!* Reserving a static port means that both Job 2
will now block on Job 1 being terminal. It will only conflict with other
tests if those tests use that port *on every node.* I ensured no
existing tests were using the port I chose.

Other changes:
- Gave job a bit more breathing room resource-wise.
- Tightened timings a bit since previous failure ran into the `go test`
  time limit.
- Cleaned up the DumpEvals output. It's quite nice and handy now!

Document how the value of `node_class` is used during cluster scaling.

https://github.com/hashicorp/nomad-autoscaler/issues/255

Use gotestsum in both GHA and Circle with retries enabled.

ACL tokens are granted permissions either by direct policy links
or via ACL role links. Callers should therefore be able to read
policies directly assigned to the caller token or indirectly by
ACL role links.

If the API returns an error during debug bundle collection the CLI was
expanding the wrong error object, resulting in a panic since `err` is
`nil`.

* refact: upgrade Promise.then to async/await

* naive solution (#14800)

* refact: use id instead of model

* chore:  add changelog entry

* refact: add conditional safety around alloc

* Generate files for 1.4.1 release

* Prepare for next release
Co-authored-by: hc-github-team-nomad-core <github-team-nomad-core@hashicorp.com>

* deps: update go-memdb for goroutine leak fix

* cl: update for goroutine leak go-memdb

And fix the one place we use them.

This changes adds ACL role creation and deletion to the event
stream. It is exposed as a single topic with two types; the filter
is primarily the role ID but also includes the role name.

While conducting this work it was also discovered that the events
stream has its own ACL resolution logic. This did not account for
ACL tokens which included role links, or tokens with expiry times.
ACL role links are now resolved to their policies and tokens are
checked for expiry correctly.

The client ACL cache was not accounting for tokens which included
ACL role links. This change modifies the behaviour to resolve role
links to policies. It will also now store ACL roles within the
cache for quick lookup. The cache TTL is configurable in the same
manner as policies or tokens.

Another small fix is included that takes into account the ACL
token expiry time. This was not included, which meant tokens with
expiry could be used past the expiry time, until they were GC'd.

Rename `Internals` section to `Concepts` to match core docs structure
and expand on how policies are evaluated.

Also include missing documentation for check grouping and fix examples
to use the new feature.

* Adds searching and filtering for nodes on topology view

* Lintfix and changelog

* Acceptance tests for topology search and filter

* Search terms also apply to class and dc on topo page

* Initialize queryparam values so as to not break history state

Move the Autoscaler agent configuration `source` to the `policy` page
since they are very closely related.

Also update all headers in this section so they follow the proper `h1 >
h2 > h3 > ...` hierarchy.

Provide more technical details about how the `target-value` strategy
calculates new scaling actions.

* fix: nomad license put link

* fix: redirected URL

* fix: avoid auto-formatting changes

* consul: register checks along with service on initial registration

This PR updates Nomad's Consul service client to include checks in
an initial service registration, so that the checks associated with
the service are registered "atomically" with the service. Before, we
would only register the checks after the service registration, which
causes problems where the service is deemed healthy, even if one or
more checks are unhealthy - especially problematic in the case where
SuccessBeforePassing is configured.

Fixes #3935

* cr: followup to fix cause of extra consul logging

* cr: fix another bug

* cr: fixup changelog

My make knowledge is very very limited, so if there's a better way to do
this please let me know! This seems to work and lets me cut one off
builds easily.