SideroLink provides an overlay Wireguard point-to-point connection from every Talos machine to the Sidero. Sidero provisions each machine with a unique IPv6 address and Wireguard key for the SideroLink connection.

Note: SideroLink is only supported with Talos >= 0.14.

SideroLink doesn’t provide a way for workload machines to communicate with each other, a connection is only point-to-point.

SideroLink connection is both encrypted and authenticated, so Sidero uses that to map data streams coming from the machines to a specific ServerBinding, MetalMachine, Machine and Cluster.

Talos node sends two streams over the SideroLink connection: kernel logs (dmesg) and Talos event stream. SideroLink is enabled automatically by Sidero when booting Talos.

Kernel Logs

Kernel logs (dmesg) are streamed in real time from the Talos nodes to the sidero-controller-manager over SideroLink connection. Log streaming starts when the kernel passes control to the init process, so kernel boot time logs will only be available when control is passed to the userland.

Logs can be accessed by accessing the logs of the serverlogs container of the sidero-controller-manager pod:

$ kubectl -n sidero-system logs deployment/sidero-controller-manager -c serverlogs -f
{"clock":8576583,"cluster":"management-cluster","facility":"user","machine":"management-cluster-cp-ddgsw","metal_machine":"management-cluster-cp-vrff4","msg":"[talos] phase mountState (6/13): 1 tasks(s)\n","namespace":"default","priority":"warning","seq":665,"server_uuid":"6b121f82-24a8-4611-9d23-fa1a5ba564f0","talos-level":"warn","talos-time":"2022-02-11T12:42:02.74807823Z"}

The format of the message is the following:

    "clock": 8576583,
    "cluster": "management-cluster",
    "facility": "user",
    "machine": "management-cluster-cp-ddgsw",
    "metal_machine": "management-cluster-cp-vrff4",
    "msg": "[talos] phase mountState (6/13): 1 tasks(s)\n",
    "namespace": "default",
    "priority": "warning",
    "seq": 665,
    "server_uuid": "6b121f82-24a8-4611-9d23-fa1a5ba564f0",
    "talos-level": "warn",
    "talos-time": "2022-02-11T12:42:02.74807823Z"

Kernel fields (see Linux documentation for details):

  • clock is the kernel timestamp relative to the boot time
  • facility of the message
  • msg is the actual log message
  • seq is the kernel log sequence
  • priority is the message priority

Talos-added fields:

  • talos-level is the translated priority into standard logging levels
  • talos-time is the timestamp of the log message (accuracy of the timestamp depends on time sync)

Sidero-added fields:

  • server_uuid is the name of the matching Server and ServerBinding resources
  • namespace is the namespace of the Cluster, MetalMachine and Machine
  • cluster, metal_machine and machine are the names of the matching Cluster, MetalMachine and Machine resources

It might be a good idea to send container logs to some log aggregation system and filter the logs for a cluster or a machine.

Quick filtering for a specific server:

kubectl -n sidero-system logs deployment/sidero-controller-manager -c serverlogs  | jq -R 'fromjson? | select(.server_uuid == "b4e677d9-b59b-4c1c-925a-f9d9ce049d79")'

Talos Events

Talos delivers system events over the SideroLink connection to the sidero-link-manager pod. These events can be accessed with talosctl events command. Events are mostly used to update ServerBinding/MetalMachine statuses, but they can be also seen in the logs of the serverevents container:

$ kubectl -n sidero-system logs deployment/sidero-controller-manager -c serverevents -f
{"level":"info","ts":1644853714.2700942,"caller":"events-manager/adapter.go:153","msg":"incoming event","component":"sink","node":"[fdae:2859:5bb1:7a03:3ae3:be30:7ec4:4c09]:44530","id":"c857jkm1jjcc7393cbs0","type":"

MetalMachine Conditions

Sidero updates the statuses of ServerBinding/MetalMachine resources based on the events received from Talos node:

  • current addresses of the node
  • statuses of machine configuration loading and validation, installation status

See Resources for details.

State of the SideroLink connection is kept in the ServerBinding resource:

    address: fdae:2859:5bb1:7a03:3ae3:be30:7ec4:4c09/64
    publicKey: XIBT49g9xCoBvyb/x36J+ASlQ4qaxXMG20ZgKbBbfE8=

Installation-wide SideroLink state is kept in the siderolink Secret resource:

$ kubectl get secrets siderolink -o yaml
apiVersion: v1
  installation-id: QUtmZGFmVGJtUGVFcWp0RGMzT1BHSzlGcmlHTzdDQ0JCSU9aRzRSamdtWT0=
  private-key: ME05bHhBd3JwV0hDczhNbm1aR3RDL1ZjK0ZSUFM5UzQwd25IU00wQ3dHOD0=

Key installation-id is used to generate unique SideroLink IPv6 addresses, and private-key is the Wireguard key of Sidero.