yaml.kubernetes.best-practice.no-fractional-cpu-limits.no-fractional-cpu-limits

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When you set a fractional CPU limit on a container, the CPU cycles available will be throttled, even though most nodes can handle processes alternating between using 100% of the CPU.

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Defintion

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rules:
  - id: no-fractional-cpu-limits
    patterns:
      - pattern-inside: |
          limits:
            ...
      - pattern: |
          cpu: $CPU_LIMIT
      - metavariable-regex:
          metavariable: $CPU_LIMIT
          regex: \d{0,3}m
    fix: "cpu: 1000m"
    message: When you set a fractional CPU limit on a container, the CPU cycles
      available will be throttled, even though most nodes can handle processes
      alternating between using 100% of the CPU.
    severity: WARNING
    languages:
      - yaml
    metadata:
      category: best-practice
      technology:
        - kubernetes
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]

Examples

no-fractional-cpu-limits.test.yaml

kind: Deployment
apiVersion: apps/v1
metadata:
  name: mumbledj
  namespace: mumble
  labels:
    app: mumbledj
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: mumbledj
  template:
    metadata:
      labels:
        app: mumbledj
    spec:
      containers:
        - name: app
          command: [/bin/mumbledj, --config, /etc/mumbledj/mumbledj.yaml]
          image: underyx/mumbledj
          volumeMounts:
            - name: mumbledj-cache
              mountPath: /root/.cache
            - name: mumbledj-config
              mountPath: /etc/mumbledj
              readOnly: true
          resources:
            limits:
              # ruleid: no-fractional-cpu-limits
              cpu: 100m
              memory: 64Mi
            requests:
              # ok: no-fractional-cpu-limits
              cpu: 20m
              memory: 32Mi
        - name: app
          image: panubo/sshd:1.1.0
          env:
            - name: SSH_USERS
              value: monosnap:667:667,sharex:749:749
            - name: SFTP_MODE
              value: "true"
          ports:
            - containerPort: 22
          volumeMounts:
            - name: images
              mountPath: /data/i.underyx.me
            - name: config
              mountPath: /etc/ssh
            - name: authorized-keys
              mountPath: /etc/authorized_keys
          lifecycle:
            postStart:
              exec:
                command: [chmod, "0777", /data/i.underyx.me]
          livenessProbe:
            tcpSocket:
              port: 22
            initialDelaySeconds: 30
            periodSeconds: 30
          resources:
            limits:
              # ok: no-fractional-cpu-limits
              cpu: 1000m
              memory: 512Mi
            requests:
              cpu: 10m
              memory: 8Mi
        - name: app
          image: plexinc/pms-docker:public
          ports:
            - containerPort: 3005
              hostPort: 3005
            - containerPort: 8324
              hostPort: 8324
            - containerPort: 32400
              hostPort: 32400
            - containerPort: 32469
              hostPort: 32469
            - containerPort: 1900
              hostPort: 1900
              protocol: UDP
            - containerPort: 32410
              hostPort: 32410
              protocol: UDP
            - containerPort: 32412
              hostPort: 32412
              protocol: UDP
            - containerPort: 32413
              hostPort: 32413
              protocol: UDP
            - containerPort: 32414
              hostPort: 32414
              protocol: UDP
          env:
            - name: TZ
              value: Europe/Prague
            - name: PLEX_UID
              value: "797"
            - name: PLEX_GID
              value: "797"
            - name: PLEX_CLAIM
              valueFrom:
                secretKeyRef:
                  name: plex-env
                  key: PLEX_CLAIM
            - name: ADVERTISE_IP
              valueFrom:
                fieldRef:
                  fieldPath: status.hostIP
          volumeMounts:
            - name: plex-config
              mountPath: /config
            - name: plex-media
              mountPath: /media
            - name: plex-transcode
              mountPath: /transcode
          livenessProbe:
            tcpSocket:
              port: 32400
            initialDelaySeconds: 30
            periodSeconds: 30
          resources:
            limits:
              # ok: no-fractional-cpu-limits
              cpu: 4000m
              memory: 2Gi
            requests:
              cpu: 1000m
              memory: 1Gi
      volumes:
        - name: mumbledj-cache
          emptyDir: {}
        - name: mumbledj-config
          secret:
            secretName: mumbledj-config