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====== EVE-KVM: Deploying a VM and configuring its network ======

This page documents how a VM (edge app instance) attaches to the network on
**EVE-OS in KVM (hypervisor) mode**, and describes **every interface binding
option** available when deploying the instance (ZedControl UI or Terraform).

> **Scope.** This is the per-instance **interface binding** — how a VM's adapters
> map onto Network Instances. It complements the NI lifecycle page (how Local and
> Switch NIs are built). Field semantics below are from the zedcloud ''appInterface''
> API model; runtime behaviour is from EVE ''pkg/pillar'' (''zedrouter'' / ''nireconciler'').

===== Two ways an interface attaches =====

Each VM adapter attaches in one of two modes, selected by the ''directattach'' flag:

  * **Network-Instance-backed** (''directattach = false'') — EVE creates a host-side **VIF** (virtio tap) and enslaves it into the NI's Linux bridge. This is the normal path; ACLs and VLAN apply here.
  * **Direct-attach** (''directattach = true'') — a **physical adapter** (whole NIC via PCI passthrough, or an SR-IOV VF) is assigned straight to the guest. No VIF, no bridge, no NI; ''netinstname''/''acls''/''access_vlan_id'' do not apply, and the physical-adapter ''type'' match is used instead.

===== What is a VIF =====

**VIF = virtual interface** — the **host-side** tap/virtio netdev EVE creates for an
NI-backed adapter. Two ends exist:

  * Inside the guest: the NIC the VM sees (e.g. becomes ''enp1s0'').
  * On the EVE host: the VIF, named ''nbu<vifNum>x<appNum>'' (e.g. ''nbu1x3''), enslaved into the NI bridge (''bnN'' or the port bridge) as a bridge port.

''domainmgr'' hands the VIF to QEMU/KVM as the backend for the guest's virtio-net
device. (EVE-K analogue: the Multus pod-side VIF; same concept, different plumbing —
tap-into-Linux-bridge here vs. CNI there.) A **direct-attach** adapter has **no VIF**.

===== Interface binding — parameter reference =====

Fields of one ''interfaces { }'' block (Terraform) = one ''appInterface'' (API) =
one row in the **Adapters & Networks** step (UI):

  * **''intfname''** — interface name the edge app expects; matched against the interface declared in the app manifest. Logical identity, not necessarily the guest's name. (EVE: ''AppNetAdapterConfig.Name''.)
  * **''intforder''** — ordering of this adapter vs. all other virtual and direct-assigned adapters. Drives the order VIFs are presented to the VM, hence PCI slot and guest NIC enumeration (eth0 vs eth1).
  * **''directattach''** — false = attach via a Network Instance (VIF on bridge); true = assign a physical adapter directly (passthrough / SR-IOV VF). See modes above.
  * **''access_vlan_id''** — access VLAN for the VIF on a **Switch** NI. ''0'' = trunk (all VLANs), ''1'' = reserved by the Linux bridge, ''2''–''4093'' = access port on that VLAN. Detailed below.
  * **''default_net_instance''** — "default instance" flag. If true the adapter binds to the device/project default NI instead of a named one; leave false when naming a NI.
  * **''ipaddr''** — static IP for the app on this interface. Per the API: if the NI's DHCP mode is static/reserved, put the reserved ''/32'' here; empty = DHCP assigns dynamically. Only meaningful on a **Local** NI (EVE runs DHCP there); inert on Switch.
  * **''macaddr''** — pin the VIF MAC (intended for P2V and DHCP=passthrough cases; also useful for MAC-bound licensing or external DHCP reservations). Empty = EVE auto-generates a deterministic MAC.
  * **''netinstname''** — the Network Instance to attach to (the **Network Instance** column in the UI). Required when ''directattach = false''. ''netinstid'' is the by-UUID alternative.
  * **''privateip''** — if true, DHCP cannot be assigned and a static IP **must** be supplied via ''ipaddr''; false = DHCP-assigned. Pairs with ''ipaddr''.
  * **''acls''** — per-interface firewall ruleset (the **Firewall Rules** column, e.g. "Edge App Configured"). Applicable only when ''directattach = false''.

===== access_vlan_id in depth =====

API model doc (''appInterface.accessVlanId''): VLAN id of zero is treated as a
**trunk** port; VLAN id 1 is **implicitly used by Linux bridges**; min ''2'', max ''4093''.
EVE implements exactly this in ''nireconciler/linux_config.go'':

<code go>
if ul.AccessVlanID <= 1 {
    vlanConfig.TrunkPort = &linux.TrunkPort{AllVIDs: true}   // 0 or 1 -> trunk, all VLANs
} else {
    vlanConfig.AccessPort = &linux.AccessPort{VID: uint16(ul.AccessVlanID)}  // >=2 -> access port
}
</code>

Three regimes:

  * **0** — VIF is a **trunk port**: the VM sees all VLANs and frames keep their 802.1Q tags. The VM does its own tagging.
  * **1** — reserved/native on the Linux bridge; behaves like the trunk/untagged case, not a usable access VLAN.
  * **2–4093** — VIF is an **access port** on that VLAN: the VM sends/receives untagged frames and the bridge tags/untags with the VID. This is how you segment multiple VMs on one Switch NI into different VLANs.

Two non-obvious behaviours:

  * **Switch NI only.** The VLAN code path is inside the ''NetworkInstanceType == Switch'' branch; on a **Local** NI the field is ignored. (This is why the UI Access VLAN field is active when the bound NI is Kind = Switch.)
  * **Bridge becomes VLAN-aware only when a VIF uses VID ≥ 2.** EVE's ''getVLANConfigForNI'' scans every app interface on the NI: if all are 0/1 the bridge stays a plain L2 switch (no filtering); the moment one VIF requests an access VLAN, EVE enables VLAN filtering and **auto-configures the physical uplink as a trunk carrying the union of all access VIDs in use** (plus the NI's ''VlanAccessPorts''). You do not trunk the uplink separately.

===== Terraform example (NI-backed VM) =====

A standalone Ubuntu VM with a single virtio adapter on a Switch NI, trunk mode
(''access_vlan_id = 0''):

<code>
resource "zedcloud_application_instance" "tf_stndlone_vm_1" {
  name       = "TF-STND-ATL-VM-1"
  title      = "TF-STND-ATL-VM-1"
  project_id = zedcloud_project.demo_zededa_project_1.id
  app_id     = zedcloud_application.tf_atl_ub_app_1.id
  activate   = true
  device_id  = zedcloud_edgenode.demo_en_advantech_1.id

  custom_config {
    add                  = true
    allow_storage_resize = true
    field_delimiter      = "@@@"
    name                 = "cloud-config"
    override             = true
    template             = base64encode(templatefile("./c-init/vm-1-enp1s0.txt", { hostname = var.vm1_hostname }))
  }

  drives {
    imagename   = zedcloud_image.demo_atl_ub_image_1.name
    cleartext   = false
    ignorepurge = false
    maxsize     = 20971520
    preserve    = false
    target      = "Disk"
    drvtype     = "HDD"
    readonly    = false
  }

  interfaces {
    intfname             = "enp1s0"                                       # adapter the app expects
    intforder            = 1                                              # NIC enumeration order in guest
    directattach         = false                                         # virtio VIF on an NI bridge
    netinstname          = zedcloud_network_instance.tf_lan_switch_1.name # which NI to attach to
    access_vlan_id       = 0                                             # 0 = trunk on the Switch NI
    default_net_instance = false                                        # use the named NI, not default
    ipaddr               = ""                                           # DHCP-assigned
    macaddr              = var.vm1_macaddr                              # pinned MAC
    privateip            = false                                        # DHCP (not static-required)
  }

  logs { access = true }
}
</code>

===== UI mapping (Adapters & Networks step) =====

^ ZedControl field        ^ Terraform / API field            ^ Notes                                            ^
| Network Adapter Name    | ''intfname''                      | the app's declared interface (e.g. ''enp3s0'')   |
| Network Instance        | ''netinstname'' / ''netinstid''   | the NI to bind (e.g. ''TF-CL250-NI-1'')          |
| Firewall Rules          | ''acls''                          | "Edge App Configured" = ACLs from the manifest   |
| Kind / Port / Addressing| (from the NI, read-only)          | e.g. Switch / eth0 / None                        |
| DHCP                    | (from the NI)                     | e.g. Default                                     |
| IP Address              | ''ipaddr''                        | static /32 when the NI is reserved-DHCP          |
| MAC Address             | ''macaddr''                       | empty = EVE auto-generates                       |
| Access VLAN Id [2-4093] | ''access_vlan_id''                | empty box == ''0'' == trunk; ≥2 = access port    |

An empty **Access VLAN Id** box is equivalent to ''access_vlan_id = 0'' (trunk),
identical in effect to the Terraform sample above.

===== Inspecting on a live EVE-KVM node =====

Via EdgeView / device debug shell:

<code bash>
# VIFs of running apps and their bridge membership
ip -br link show | grep nbu
bridge link show | grep nbu                 # nbu1x3 master bn1 (or the port bridge)

# Is the bridge VLAN-aware, and what VIDs are programmed?
bridge vlan show                            # access PVID per VIF, trunk VIDs on the uplink

# App network status as zedrouter sees it
cat /run/zedrouter/AppNetworkStatus/*.json | jq '{app:.DisplayName, vifs:.UnderlayNetworkList[]?|{name:.Name, vif:.Vif, bridge:.Bridge, mac:.Mac, vlan:.AccessVlanID, ip:.AllocatedIPv4Addr}}'
</code>

===== Source references =====

  * Per-interface model — zedcloud ''appInterface'' (swagger): ''accessVlanId'' (min 2 / max 4093; 0 = trunk, 1 = bridge-reserved), ''directattach'', ''intfname'', ''intforder'', ''ipaddr'', ''macaddr'', ''netinstname''/''netinstid'', ''defaultNetInstance'', ''privateip''.
  * VLAN application — ''nireconciler/linux_config.go'' (''AccessVlanID <= 1'' → trunk; ''>= 2'' → access port; ''getVLANConfigForNI'' computes uplink trunk VIDs).
  * App adapter config / VIF naming — ''types/zedroutertypes.go'' (''AppNetAdapterConfig''), ''nireconciler'' (''nbu<vifNum>x<appNum>'').