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kubernetes (k8s)

Tags: computers, distributed systems

Tracing

  • Need

    securityContext: capabilities: add:

    • SYS_PTRACE

    added to the pod to allow for strace and ptrace to work. Example:

    
apiVersion: v1
kind: Pod
metadata:
  name: <POD_NAME>
  namespace: default
spec:
  containers:
    image: <IMAGE>
    imagePullPolicy: IfNotPresent
    name: web
    command: ["/bin/sleep"]
    args: ["1000000"]
    securityContext:
      capabilities:
        add:
​        - SYS_PTRACE
    ports:
​    - containerPort: 80
      name: http
      protocol: TCP
    resources:
      limits:
        cpu: "40"
        memory: 100G
      requests:
        cpu: "38"
        memory: 100G
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
​    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-qtpks
      readOnly: true

Kubernetes get all logs for pods of a specific type

kubectl get pods -o wide |  rg '<POD_NAME> ' | rg '0/1' --fixed-strings | rg '<POD_NAME>.{20}\s' -o | cut -d ' ' -f 1 | xargs -L 1 kubectl logs --tail 10

Kube 1.24 and 1.25 major changes

Things to worry about

  • volumesnapshot?

Cloud Native postgres

Kubeshark (API traffic analyzer for kube)

BSD Jails vs cgroups and namespaces

  • BSD jails, solaris zones, and linux cgroups + namespaces all do the same thing
  • Containers are built on top of cgroups and namespaces

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