Store external NTP & DNS servers in DB and allow updating them.

[luqmana]

We require ntp_servers and dns_servers at RSS today but don't persist that in the DB nor allow them to be changed without re-initializing the rack. It's conceivable a customer will want to update these on a running system.

[davepacheco]

Are these not stored anywhere right now? If a Nexus restarts, is it forever unable to use external DNS?

[luqmana]

Are these not stored anywhere right now? If a Nexus restarts, is it forever unable to use external DNS?

Ah, I guess to be clear we store a subset of the RSS parameters incl ntp/dns servers on disk at /pool/int/.../config/sled-agent-request.toml, e.g.:

{
  "request": {
    "id": "e7fbb24f-34b9-4584-95cc-259fccab6475",
    "rack_id": "c41df6b8-d16a-4939-be94-673cbd3d3e9b",
    "ntp_servers": [
      "ntp.eng.oxide.computer"
    ],
    "dns_servers": [
      "1.1.1.1",
      "9.9.9.9"
    ],
    "use_trust_quorum": false,
    "subnet": {
      "net": "fd00:1122:3344:101::/64"
    }
  }
}

For specific services, like boundary ntp (and now Nexus) it's also part of the sled plan generated for whatever sled is hosting those services, also stored on disk at /pool/int/.../config/services.toml. e.g.:

{
  "generation": 5,
  "requests": [
    {
      "zone": {
        "id": "748c6a8f-c424-4dab-ac0c-12a6cb1b5660",
        "zone_type": "nexus",
        "addresses": [
          "fd00:1122:3344:101::a"
        ],
        "dataset": null,
        "services": [
          {
            "id": "748c6a8f-c424-4dab-ac0c-12a6cb1b5660",
            "details": {
              "type": "nexus",
              "internal_address": "[fd00:1122:3344:101::a]:12221",
              "external_ip": "172.17.16.13",
              "nic": {
                "id": "7aa24c9a-ca0f-4236-8b1c-fe271d4f135f",
                "kind": {
                  "type": "service",
                  "id": "748c6a8f-c424-4dab-ac0c-12a6cb1b5660"
                },
                "name": "nexus-748c6a8f-c424-4dab-ac0c-12a6cb1b5660",
                "ip": "172.30.2.6",
                "mac": "A8:40:25:FF:D3:11",
                "subnet": "172.30.2.0/24",
                "vni": 100,
                "primary": true,
                "slot": 0
              },
              "external_tls": true,
              "external_dns_servers": [
                "1.1.1.1",
                "9.9.9.9"
              ]
            }
          }
        ],
        "boundary_switches": [
          "fd00:1122:3344:101::2"
        ]
      },
      "root": "/pool/ext/24b4dc87-ab46-49fb-a4b4-d361ae214c03/crypt/zone"
    },
    {
      "zone": {
        "id": "eccb6cf4-f73a-4816-9a33-158773f29353",
        "zone_type": "ntp",
        "addresses": [
          "fd00:1122:3344:101::16"
        ],
        "dataset": null,
        "services": [
          {
            "id": "eccb6cf4-f73a-4816-9a33-158773f29353",
            "details": {
              "type": "boundary_ntp",
              "address": "[fd00:1122:3344:101::16]:123",
              "ntp_servers": [
                "ntp.eng.oxide.computer"
              ],
              "dns_servers": [
                "1.1.1.1",
                "9.9.9.9"
              ],
              "domain": null,
              "nic": {
                "id": "b12b5227-e4e6-4d82-985a-a6ee4b3de92a",
                "kind": {
                  "type": "service",
                  "id": "eccb6cf4-f73a-4816-9a33-158773f29353"
                },
                "name": "ntp-eccb6cf4-f73a-4816-9a33-158773f29353",
                "ip": "172.30.3.5",
                "mac": "A8:40:25:FF:B0:64",
                "subnet": "172.30.3.0/24",
                "vni": 100,
                "primary": true,
                "slot": 0
              },
              "snat_cfg": {
                "ip": "172.17.16.15",
                "first_port": 0,
                "last_port": 16383
              }
            }
          }
        ],
        "boundary_switches": [
          "fd00:1122:3344:101::2"
        ]
      }
     // ...snip...
  ]
}

For Nexus then, on service startup that's used to create the DeploymentConfig and then further make our external resolver.