client: handle 0.8 server network resources

[notnoop]

Fixes #5587

When a nomad 0.9 client is handling an alloc generated by a nomad 0.8
server, we should check the alloc.TaskResources for networking details
rather than task.Resources.

We check alloc.TaskResources for networking for other tasks in the task
group [1], so it's a bit odd that we used the task.Resources struct
here. TaskRunner also uses alloc.TaskResources[2].

The task.Resources struct in 0.8 was sparsly populated, resulting to
storing of 0 in port mapping env vars:

vagrant@nomad-server-01:~$ nomad version
Nomad v0.8.7 (21a2d93eecf018ad2209a5eab6aae6c359267933+CHANGES)
vagrant@nomad-server-01:~$ nomad server members
Name                    Address      Port  Status  Leader  Protocol  Build  Datacenter  Region
nomad-server-01.global  10.199.0.11  4648  alive   true    2         0.8.7  dc1         global
vagrant@nomad-server-01:~$ nomad alloc status -json 5b34649b | jq '.Job.TaskGroups[0].Tasks[0].Resources.Networks'
[
  {
    "CIDR": "",
    "Device": "",
    "DynamicPorts": [
      {
        "Label": "db",
        "Value": 0
      }
    ],
    "IP": "",
    "MBits": 10,
    "ReservedPorts": null
  }
]
vagrant@nomad-server-01:~$ nomad alloc status -json 5b34649b | jq '.TaskResources'
{
  "redis": {
    "CPU": 500,
    "DiskMB": 0,
    "IOPS": 0,
    "MemoryMB": 256,
    "Networks": [
      {
        "CIDR": "",
        "Device": "eth1",
        "DynamicPorts": [
          {
            "Label": "db",
            "Value": 21722
          }
        ],
        "IP": "10.199.0.21",
        "MBits": 10,
        "ReservedPorts": null
      }
    ]
  }
}

Also, updated the test values to mimic how Nomad 0.8 structs are
represented, and made its result match the non compact values in
TestEnvironment_AsList.

[1]

nomad/client/taskenv/env.go

Lines 624 to 639 in 24e9040

	} else if alloc.TaskResources != nil {
	for taskName, resources := range alloc.TaskResources {
	// Add ports from other tasks
	if taskName == b.taskName {
	continue
	}
	for _, nw := range resources.Networks {
	for _, p := range nw.ReservedPorts {
	addPort(b.otherPorts, taskName, nw.IP, p.Label, p.Value)
	}
	for _, p := range nw.DynamicPorts {
	addPort(b.otherPorts, taskName, nw.IP, p.Label, p.Value)
	}
	}
	}
	}

[2] https://github.com/hashicorp/nomad/blob/master/client/allocrunner/taskrunner/task_runner.go#L287-L303

[notnoop]

I'm unclear how values in the tests were chosen - given that rest of tests don't reference admin port and 2000/5000 don't appear in the final expected results. I did my best to capture what the intent of test is and made values consistent with how this and the values in TestEnvironment_AsList so both tests get the same expected output.

[nickethier]

I think we're moving everything to use the AllocatedResources field, this is still needed for compatibility but I would add a comment.

nomad/nomad/structs/structs.go

Lines 7382 to 7386 in a988ae8

	// COMPAT(0.11): Remove in 0.11
	// TaskResources is the set of resources allocated to each
	// task. These should sum to the total Resources. Dynamic ports will be
	// set by the scheduler.
	TaskResources map[string]*Resources

[notnoop]

The if statement where this appears now is entirely about compatibility and already commented in

nomad/client/taskenv/env.go

Lines 587 to 589 in 4a16a31

	// COMPAT(0.11): Remove in 0.11
	b.otherPorts = make(map[string]string, len(alloc.Job.LookupTaskGroup(alloc.TaskGroup).Tasks)*2)
	if alloc.AllocatedResources != nil {

.

[github-actions]

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