Traffic Operator

Deployment

There are two ways to deploy the Traffic Operator:

1. With OLM (use make olm-install to install OLM in case it's not installed):

   make olm-deploy

2. Without OLM:

   make install deploy

Operator can be installed in any namespace, the default is traffic-operator-system. Repo also contains mock deployment traffic_generator.yaml.

Docker images used by Traffic Operator:

• pkopel/traffic-operator-catalog - image for OLM's CatalogSource CR
• pkopel/traffic-operator-bundle - CRDs and other resources for OLM
• pkopel/traffic-operator - controller image

Overview

Traffic Operator monitors network usage on worker nodes and marks them with labels based on threshold configured in TrafficWatch CR. Network usage metrics are provided by Node Exporter DaemonSet deployed by the operator on startup. TrafficWatch CRs also contain specification of a Deployment that is being created and managed by the Traffic Operator. The deployment is created after two reconciliations to allow for gathering traffic data.

Traffic generator

Apart from Traffic Operator, this repo contains also a simple configuration to mock network traffic on cluster, the traffic-generator. It contains a Namespace, a Service and a Deployment. Each Pod contains two containers, server and client. server is a simple http echo server, that is called by clients through the service, with data generated for each request from /dev/rand.

Custom Resource

Traffic Operator uses one simple Custom Resource named TrafficWatch:

apiVersion: traffic.example.com/v1alpha1
kind: TrafficWatch
metadata:
  name: trafficwatch-sample
spec:
  maxBandwidthPercent: "60"
  deployment:selector:
      matchLabels:
        app.kubernetes.io/component: trafficwatch-sample
        app.kubernetes.io/name: trafficwatch-sample
    replicas: 2
    template:
      metadata:
        labels:
          app.kubernetes.io/component: trafficwatch-sample
          app.kubernetes.io/name: trafficwatch-sample
      spec:
        containers:
          - name: example-app
            image: example-app/image
            resources:
              limits:
                cpu: 500m
                memory: 128Mi
              requests:
                cpu: 10m
                memory: 64Mi
            command: ["app"]

Important: spec.maxBandwidthPercent is a string, not a number, to allow for use of fractions (like 1.5e-03).

Traffic Operator will create a deployment based on configuration provided in TrafficWatch and configure nodeAffinity so that pods will be created only on 'fit' nodes. Operator will mark nodes with labels specific for each TrafficWatch resource.

Reconciled TrafficWatch contains information about current network traffic on each worker node:

apiVersion: traffic.example.com/v1alpha1
kind: TrafficWatch
metadata:
  name: trafficwatch-sample
  namespace: default
spec:
  maxBandwidthPercent: "60"
  deployment:selector:
      matchLabels:
        app.kubernetes.io/component: trafficwatch-sample
        app.kubernetes.io/name: trafficwatch-sample
    replicas: 2
    template:
      metadata:
        labels:
          app.kubernetes.io/component: trafficwatch-sample
          app.kubernetes.io/name: trafficwatch-sample
      spec:
        containers:
          - name: example-app
            image: example-app/image
            resources:
              limits:
                cpu: 500m
                memory: 128Mi
              requests:
                cpu: 10m
                memory: 64Mi
            command: ["app"]
status:
  nodes:
    kind-worker:
      currentBandwidthPercent: "1.06976e-04"
      currentTransmitTotal: 281814
      time: 1654276365
      unfit: false
    kind-worker2:
      currentBandwidthPercent: "9.784e-05"
      currentTransmitTotal: 283700
      time: 1654276366
      unfit: false
  ready: true

Reconciliation loop

Reconciliation loop consists of following steps:

1. Finding Node Exporter endpoints on each worker node

2. Polling each endpoint to get current network usage information

3. Computing average bandwidth used on each worker node from information saved in TrafficWatch and metrics provided by Node Exporter

4. If a node is in the same 'fit/unfit' state for two consecutive reconciliations, operator updates labels on it to reflect that state

5. Creating/updating Deployment defined in TrafficWatch if the TrafficWatch is marked as ready (which happens after two succesfull reconciliations)

6. Saving current statistics in TrafficWatch

Reconciliation loop runs every 10s for each TrafficWatch CR if everything is alright, in case of errors reconciler waits 30s before next attempt. To limit number of reconciliation loop runs, controller uses a filter discarding update events that don't change spec field of the TrafficWatch CR.

Repo contents

• bundle - OLM bundle resources
• config - yaml files
• internal - controller code
• api - api definitions