This changelog is for a PR that landed in Nomad Enterprise only.

The `consul.client_auto_join` configuration block tells the Nomad
client whether to use Consul service discovery to find Nomad
servers. By default it is set to `true`, but contrary to the
documentation it was only respected during the initial client
registration. If a client missed a heartbeat, failed a
`Node.UpdateStatus` RPC, or if there was no Nomad leader, the client
would fallback to Consul even if `client_auto_join` was set to
`false`. This changeset returns early from the client's trigger for
Consul discovery if the `client_auto_join` field is set to `false`.

In the system scheduler, if a subset of clients are filtered by class,
we hit a code path where the `AllocMetric` has been copied, but the
`Copy` method does not instantiate the various maps. This leads to an
assignment to a nil map. This changeset ensures that the maps are
non-nil before continuing.

The `Copy` method relies on functions in the `helper` package that all
return nil slices or maps when passed zero-length inputs. This
changeset to fix the panic bug intentionally defers updating those
functions because it'll have potential impact on memory usage. See
https://github.com/hashicorp/nomad/issues/11564 for more details.

In the system scheduler, if a subset of clients are filtered by class,
we hit a code path where the `AllocMetric` has been copied, but the
`Copy` method does not instantiate the various maps. This leads to an
assignment to a nil map. This changeset ensures that the maps are
non-nil before continuing.

The `Copy` method relies on functions in the `helper` package that all
return nil slices or maps when passed zero-length inputs. This
changeset to fix the panic bug intentionally defers updating those
functions because it'll have potential impact on memory usage. See
https://github.com/hashicorp/nomad/issues/11564 for more details.

This change modifies the Nomad job register and deregister RPCs to
accept an updated option set which includes eval priority. This
param is optional and override the use of the job priority to set
the eval priority.

In order to ensure all evaluations as a result of the request use
the same eval priority, the priority is shared to the
allocReconciler and deploymentWatcher. This creates a new
distinction between eval priority and job priority.

The Nomad agent HTTP API has been modified to allow setting the
eval priority on job update and delete. To keep consistency with
the current v1 API, job update accepts this as a payload param;
job delete accepts this as a query param.

Any user supplied value is validated within the agent HTTP handler
removing the need to pass invalid requests to the server.

The register and deregister opts functions now all for setting
the eval priority on requests.

The chan...

The QEMU driver allows arbitrary command line options, but many of
these options give access to host resources that operators may not
want to expose such as devices. Add an optional allowlist to the
plugin configuration so that operators can limit the resources for
QEMU.

* api: return 404 for alloc FS list/stat endpoints

If the alloc filesystem doesn't have a file requested by the List
Files or Stat File API, we currently return a HTTP 500 error with the
expected "file not found" error message. Return a HTTP 404 error
instead.

* update FS Handler

Previously the FS handler would interpret a 500 status as a 404
in the adapter layer by checking if the response body contained
the text  or is the response status
was 500 and then throw an error code for 404.
Co-authored-by: Jai Bhagat <jaybhagat841@gmail.com>

go-getter 1.5.9 includes a patch in 1.5.6 that automatically unpacks
uncompressed tar archives. Previously Nomad only unpacked compressed
archives, but documented that it unpacked all archives.

* debug: refactor Consul API collection
* debug: refactor Vault API collection
* debug: cleanup test timing
* debug: extend test to multiregion
* debug: save cmdline flags in bundle
* debug: add cli version to output
* Add changelog entry

Enhance the CLI in order to return the host network in two flavors 
(default, verbose) of the `node status` command.

Fixes: #11223.
Signed-off-by: Alessandro De Blasis <alex@deblasis.net>

Co-authored-by: James Rasell <jrasell@hashicorp.com>

- Making RPC Upgrade mode reloadable.
- Add suggestions from code review
- remove spurious comment
- switch to require(t,...) form for test.
- Add to changelog

As we have continued to see reports of #9506 we need to elevate this log
line as it is the only way to detect when plans are being *erroneously*
rejected.

Users who see this log line repeatedly should drain and restart the node
in the log line. This seems to workaorund the issue.

Please post any details on #9506!

* debug: default node-id to all
* debug: align cli help and website documentation

Log the failure error when the agent fails to start. Previously, the
agent startup failure error would be emitted to the command UI but not
logged. So it doesn't get emitted to syslog or `log_file` if they are
set, and it makes debugging much harder. Also, logging the error again
before exit makes the error more visible: previously, the operator
needed to scroll to the top to find the error.

On a sample failure, the output will look like:
```
==> WARNING: Bootstrap mode enabled! Potentially unsafe operation.
==> Loaded configuration from sample-configs/config-bad
==> Starting Nomad agent...
==> Error starting agent: setting up server node ID failed: mkdir /path-without-permission: read-only file system
    2021-10-20T14:38:51.179-0400 [WARN]  agent.plugin_loader: skipping external plugins since plugin_dir doesn't exist: plugin_dir=/path-without-permission/plugins
    2021-10-20T14:38:51.181-0400 [DEBUG] agent.plugin_loader.docker:...

Closes: #11395 .

The system scheduler should leave allocs on draining nodes as-is, but
stop node stop allocs on nodes that are no longer part of the job
datacenters.

Previously, the scheduler did not make the distinction and left system
job allocs intact if they are already running.

I've added a failing test first, which you can see in https://app.circleci.com/jobs/github/hashicorp/nomad/179661 .

Fixes https://github.com/hashicorp/nomad/issues/11373

Pick up https://github.com/golang/snappy/pull/56 to handle arm64 architectures to fix panics. tldr; Golang 1.16 changed `memmove` implementation for arm64 requiring additional cpu registers that snappy wasn't preserving in its assembly implementation.

Other projects have experienced this issue as well, searching for `encode_arm64.s:666` on your favorite search engine will reveal some.  Vault updated the dependency earlier this August: https://github.com/hashicorp/vault/pull/12371 .

I believe this issue affects Nomad 1.2.x and 1.1.x. Nomad 1.0.x use Golang 1.15 and isn't affected. However, backporting the change to 1.0.x should be harmless.

Fixed https://github.com/hashicorp/nomad/issues/11385 .