nomad node status -verbose panics when a running alloc uses a host volume

[notnoop]

Nomad version

Output from `nomad version`
root@nomad-client-1:~# nomad version
Nomad v0.12.4 (8efaee4ba5e9727ab323aaba2ac91c2d7b572d84)

Operating system and Environment details

In https://play.instruqt.com/hashicorp/tracks/nomad-host-volumes - in the last exercise "Write Data to the MySQL Database`

Issue

If a running allocation on a node uses a Host Volume, then nomad node status -verbose panics.

The reason is that the running allocation reports the Host Volume, which nomad node status -verbose mistakes as a CSI volume. Then when the nomad CLI attempts to print the nil CSI volume, it panics. The relevant code is in https://github.com/hashicorp/nomad/blob/v0.12.4/command/node_status.go#L545-L593 .

Some observations

root@nomad-client-1:~# nomad alloc status  --json c916bd47 | jq '.Job.TaskGroups[0].Volumes'
{
  "mysql_volume": {
    "MountOptions": null,
    "Name": "mysql_volume",
    "ReadOnly": false,
    "Source": "mysql",
    "Type": "host"
  }
}
root@nomad-client-1:~# nomad node status  -self
ID              = dd635239-afef-c695-5fff-d59329f4984b
Name            = client1
Class           = <none>
DC              = dc1
Drain           = false
Eligibility     = eligible
Status          = ready
CSI Controllers = <none>
CSI Drivers     = <none>
Uptime          = 1h14m0s
Host Volumes    = mysql
CSI Volumes     = mysql_volume
Driver Status   = docker,exec,java

Node Events
Time                  Subsystem  Message
2020-09-16T14:56:23Z  Cluster    Node registered

Allocated Resources
CPU           Memory           Disk
500/2300 MHz  1.0 GiB/3.6 GiB  300 MiB/15 GiB

Allocation Resource Utilization
CPU         Memory
7/2300 MHz  370 MiB/3.6 GiB
Host Resource Utilization
CPU         Memory           Disk
0/2300 MHz  686 MiB/3.6 GiB  4.7 GiB/19 GiB

Allocations
ID        Node ID   Task Group    Version  Desired  Status   Created     Modified
c916bd47  dd635239  mysql-server  0        run      running  17m47s ago  17m4s ago
root@nomad-client-1:~# nomad node status --verbose -self
ID              = dd635239-afef-c695-5fff-d59329f4984b
Name            = client1
Class           = <none>
DC              = dc1
Drain           = false
Eligibility     = eligible
Status          = ready
CSI Controllers = <none>
CSI Drivers     = <none>
Uptime          = 1h14m8s

Host Volumes
Name   ReadOnly  Source
mysql  false     /opt/mysql/data

CSI Volumes
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x25cc97b]

goroutine 1 [running]:
github.com/hashicorp/nomad/command.(*NodeStatusCommand).outputNodeCSIVolumeInfo(0xc000118ea0, 0xc0001fe850, 0xc0002c2fc0, 0x
c0003103f0, 0x1, 0x1)
        github.com/hashicorp/nomad/command/node_status.go:583 +0x6ab
github.com/hashicorp/nomad/command.(*NodeStatusCommand).formatNode(0xc000118ea0, 0xc0001fe850, 0xc0002c2fc0, 0x0)
        github.com/hashicorp/nomad/command/node_status.go:436 +0x1a93
github.com/hashicorp/nomad/command.(*NodeStatusCommand).Run(0xc000118ea0, 0xc00004e0d0, 0x2, 0x2, 0xc000123090)
        github.com/hashicorp/nomad/command/node_status.go:279 +0x87f
github.com/mitchellh/cli.(*CLI).Run(0xc0001cedc0, 0xc0001cedc0, 0xc0001ef5e0, 0x38)
        github.com/mitchellh/[email protected]/cli.go:260 +0x1da
main.RunCustom(0xc00004e0b0, 0x4, 0x4, 0xc0000a2058)
        github.com/hashicorp/nomad/main.go:142 +0x482
main.Run(...)
        github.com/hashicorp/nomad/main.go:87
main.main()
        github.com/hashicorp/nomad/main.go:83 +0x64

Sorry the instance died as my session expired before my data got more data.

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