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Logging

Dealing with Talos Linux logs.

Viewing logs

Kernel messages can be retrieved with talosctl dmesg command:

$ talosctl -n 172.20.1.2 dmesg

172.20.1.2: kern:    info: [2021-11-10T10:09:37.662764956Z]: Command line: init_on_alloc=1 slab_nomerge pti=on consoleblank=0 nvme_core.io_timeout=4294967295 printk.devkmsg=on ima_template=ima-ng ima_appraise=fix ima_hash=sha512 console=ttyS0 reboot=k panic=1 talos.shutdown=halt talos.platform=metal talos.config=http://172.20.1.1:40101/config.yaml
[...]

Service logs can be retrieved with talosctl logs command:

$ talosctl -n 172.20.1.2 services

NODE         SERVICE      STATE     HEALTH   LAST CHANGE   LAST EVENT
172.20.1.2   apid         Running   OK       19m27s ago    Health check successful
172.20.1.2   containerd   Running   OK       19m29s ago    Health check successful
172.20.1.2   cri          Running   OK       19m27s ago    Health check successful
172.20.1.2   etcd         Running   OK       19m22s ago    Health check successful
172.20.1.2   kubelet      Running   OK       19m20s ago    Health check successful
172.20.1.2   machined     Running   ?        19m30s ago    Service started as goroutine
172.20.1.2   trustd       Running   OK       19m27s ago    Health check successful
172.20.1.2   udevd        Running   OK       19m28s ago    Health check successful

$ talosctl -n 172.20.1.2 logs machined

172.20.1.2: [talos] task setupLogger (1/1): done, 106.109µs
172.20.1.2: [talos] phase logger (1/7): done, 564.476µs
[...]

Container logs for Kubernetes pods can be retrieved with talosctl logs -k command:

$ talosctl -n 172.20.1.2 containers -k
NODE         NAMESPACE   ID                                                 IMAGE                                                         PID    STATUS
172.20.1.2   k8s.io      kube-system/kube-flannel-dk6d5                     registry.k8s.io/pause:3.6                                     1329   SANDBOX_READY
172.20.1.2   k8s.io      └─ kube-system/kube-flannel-dk6d5:install-cni      ghcr.io/siderolabs/install-cni:v0.7.0-alpha.0-1-g2bb2efc      0      CONTAINER_EXITED
172.20.1.2   k8s.io      └─ kube-system/kube-flannel-dk6d5:install-config   quay.io/coreos/flannel:v0.13.0                                0      CONTAINER_EXITED
172.20.1.2   k8s.io      └─ kube-system/kube-flannel-dk6d5:kube-flannel     quay.io/coreos/flannel:v0.13.0                                1610   CONTAINER_RUNNING
172.20.1.2   k8s.io      kube-system/kube-proxy-gfkqj                       registry.k8s.io/pause:3.5                                     1311   SANDBOX_READY
172.20.1.2   k8s.io      └─ kube-system/kube-proxy-gfkqj:kube-proxy         registry.k8s.io/kube-proxy:v1.26.3                            1379   CONTAINER_RUNNING

$ talosctl -n 172.20.1.2 logs -k kube-system/kube-proxy-gfkqj:kube-proxy
172.20.1.2: 2021-11-30T19:13:20.567825192Z stderr F I1130 19:13:20.567737       1 server_others.go:138] "Detected node IP" address="172.20.0.3"
172.20.1.2: 2021-11-30T19:13:20.599684397Z stderr F I1130 19:13:20.599613       1 server_others.go:206] "Using iptables Proxier"
[...]

Sending logs

Service logs

You can enable logs sendings in machine configuration:

machine:
  logging:
    destinations:
      - endpoint: "udp://127.0.0.1:12345/"
        format: "json_lines"
      - endpoint: "tcp://host:5044/"
        format: "json_lines"

Several destinations can be specified. Supported protocols are UDP and TCP. The only currently supported format is json_lines:

{
  "msg": "[talos] apply config request: immediate true, on reboot false",
  "talos-level": "info",
  "talos-service": "machined",
  "talos-time": "2021-11-10T10:48:49.294858021Z"
}

Messages are newline-separated when sent over TCP. Over UDP messages are sent with one message per packet. msg, talos-level, talos-service, and talos-time fields are always present; there may be additional fields.

Kernel logs

Kernel log delivery can be enabled with the talos.logging.kernel kernel command line argument, which can be specified in the .machine.installer.extraKernelArgs:

machine:
  install:
    extraKernelArgs:
      - talos.logging.kernel=tcp://host:5044/

Kernel log destination is specified in the same way as service log endpoint. The only supported format is json_lines.

Sample message:

{
  "clock":6252819, // time relative to the kernel boot time
  "facility":"user",
  "msg":"[talos] task startAllServices (1/1): waiting for 6 services\n",
  "priority":"warning",
  "seq":711,
  "talos-level":"warn", // Talos-translated `priority` into common logging level
  "talos-time":"2021-11-26T16:53:21.3258698Z" // Talos-translated `clock` using current time
}

extraKernelArgs in the machine configuration are only applied on Talos upgrades, not just by applying the config. (Upgrading to the same version is fine).

Filebeat example

To forward logs to other Log collection services, one way to do this is sending them to a Filebeat running in the cluster itself (in the host network), which takes care of forwarding it to other endpoints (and the necessary transformations).

If Elastic Cloud on Kubernetes is being used, the following Beat (custom resource) configuration might be helpful:

apiVersion: beat.k8s.elastic.co/v1beta1
kind: Beat
metadata:
  name: talos
spec:
  type: filebeat
  version: 7.15.1
  elasticsearchRef:
    name: talos
  config:
    filebeat.inputs:
      - type: "udp"
        host: "127.0.0.1:12345"
        processors:
          - decode_json_fields:
              fields: ["message"]
              target: ""
          - timestamp:
              field: "talos-time"
              layouts:
                - "2006-01-02T15:04:05.999999999Z07:00"
          - drop_fields:
              fields: ["message", "talos-time"]
          - rename:
              fields:
                - from: "msg"
                  to: "message"

  daemonSet:
    updateStrategy:
      rollingUpdate:
        maxUnavailable: 100%
    podTemplate:
      spec:
        dnsPolicy: ClusterFirstWithHostNet
        hostNetwork: true
        securityContext:
          runAsUser: 0
        containers:
          - name: filebeat
            ports:
              - protocol: UDP
                containerPort: 12345
                hostPort: 12345

The input configuration ensures that messages and timestamps are extracted properly. Refer to the Filebeat documentation on how to forward logs to other outputs.

Also note the hostNetwork: true in the daemonSet configuration.

This ensures filebeat uses the host network, and listens on 127.0.0.1:12345 (UDP) on every machine, which can then be specified as a logging endpoint in the machine configuration.

Fluent-bit example

First, we’ll create a value file for the fluentd-bit Helm chart.

# fluentd-bit.yaml

podAnnotations:
  fluentbit.io/exclude: 'true'

extraPorts:
  - port: 12345
    containerPort: 12345
    protocol: TCP
    name: talos

config:
  service: |
    [SERVICE]
      Flush         5
      Daemon        Off
      Log_Level     warn
      Parsers_File  custom_parsers.conf    

  inputs: |
    [INPUT]
      Name          tcp
      Listen        0.0.0.0
      Port          12345
      Format        json
      Tag           talos.*

    [INPUT]
      Name          tail
      Alias         kubernetes
      Path          /var/log/containers/*.log
      Parser        containerd
      Tag           kubernetes.*

    [INPUT]
      Name          tail
      Alias         audit
      Path          /var/log/audit/kube/*.log
      Parser        audit
      Tag           audit.*    

  filters: |
    [FILTER]
      Name                kubernetes
      Alias               kubernetes
      Match               kubernetes.*
      Kube_Tag_Prefix     kubernetes.var.log.containers.
      Use_Kubelet         Off
      Merge_Log           On
      Merge_Log_Trim      On
      Keep_Log            Off
      K8S-Logging.Parser  Off
      K8S-Logging.Exclude On
      Annotations         Off
      Labels              On

    [FILTER]
      Name          modify
      Match         kubernetes.*
      Add           source kubernetes
      Remove        logtag    

  customParsers: |
    [PARSER]
      Name          audit
      Format        json
      Time_Key      requestReceivedTimestamp
      Time_Format   %Y-%m-%dT%H:%M:%S.%L%z

    [PARSER]
      Name          containerd
      Format        regex
      Regex         ^(?<time>[^ ]+) (?<stream>stdout|stderr) (?<logtag>[^ ]*) (?<log>.*)$
      Time_Key      time
      Time_Format   %Y-%m-%dT%H:%M:%S.%L%z    

  outputs: |
    [OUTPUT]
      Name    stdout
      Alias   stdout
      Match   *
      Format  json_lines    

  # If you wish to ship directly to Loki from Fluentbit,
  # Uncomment the following output, updating the Host with your Loki DNS/IP info as necessary.
  # [OUTPUT]
  # Name loki
  # Match *
  # Host loki.loki.svc
  # Port 3100
  # Labels job=fluentbit
  # Auto_Kubernetes_Labels on

daemonSetVolumes:
  - name: varlog
    hostPath:
      path: /var/log

daemonSetVolumeMounts:
  - name: varlog
    mountPath: /var/log

tolerations:
  - operator: Exists
    effect: NoSchedule

Next, we will add the helm repo for FluentBit, and deploy it to the cluster.

helm repo add fluent https://fluent.github.io/helm-charts
helm upgrade -i --namespace=kube-system -f fluentd-bit.yaml fluent-bit fluent/fluent-bit

Now we need to find the service IP.

$ kubectl -n kube-system get svc -l app.kubernetes.io/name=fluent-bit

NAME         TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)             AGE
fluent-bit   ClusterIP   10.200.0.138   <none>        2020/TCP,5170/TCP   108m

Finally, we will change talos log destination with the command talosctl edit mc.

machine:
  logging:
    destinations:
      - endpoint: "tcp://10.200.0.138:5170"
        format: "json_lines"

This example configuration was well tested with Cilium CNI, and it should work with iptables/ipvs based CNI plugins too.

Vector example

Vector is a lightweight observability pipeline ideal for a Kubernetes environment. It can ingest (source) logs from multiple sources, perform remapping on the logs (transform), and forward the resulting pipeline to multiple destinations (sinks). As it is an end to end platform, it can be run as a single-deployment ‘aggregator’ as well as a replicaSet of ‘Agents’ that run on each node.

As Talos can be set as above to send logs to a destination, we can run Vector as an Aggregator, and forward both kernel and service to a UDP socket in-cluster.

Below is an excerpt of a source/sink setup for Talos, with a ‘sink’ destination of an in-cluster Grafana Loki log aggregation service. As Loki can create labels from the log input, we have set up the Loki sink to create labels based on the host IP, service and facility of the inbound logs.

Note that a method of exposing the Vector service will be required which may vary depending on your setup - a LoadBalancer is a good option.

role: "Stateless-Aggregator"

# Sources
sources:
  talos_kernel_logs:
    address: 0.0.0.0:6050
    type: socket
    mode: udp
    max_length: 102400
    decoding:
      codec: json
    host_key: __host

  talos_service_logs:
    address: 0.0.0.0:6051
    type: socket
    mode: udp
    max_length: 102400
    decoding:
      codec: json
    host_key: __host

# Sinks
sinks:
  talos_kernel:
    type: loki
    inputs:
      - talos_kernel_logs_xform
    endpoint: http://loki.system-monitoring:3100
    encoding:
      codec: json
      except_fields:
        - __host
    batch:
      max_bytes: 1048576
    out_of_order_action: rewrite_timestamp
    labels:
      hostname: >-
                {{`{{ __host }}`}}
      facility: >-
                {{`{{ facility }}`}}

  talos_service:
    type: loki
    inputs:
      - talos_service_logs_xform
    endpoint: http://loki.system-monitoring:3100
    encoding:
      codec: json
      except_fields:
        - __host
    batch:
      max_bytes: 400000
    out_of_order_action: rewrite_timestamp
    labels:
      hostname: >-
                {{`{{ __host }}`}}
      service: >-
                {{`{{ "talos-service" }}`}}
Last modified December 13, 2022: docs: update documentation for Talos 1.3 (474604cd2)