Where To Modify Starting Arguments of K8S Core Components

Requirement:

  We have a kubernetes cluster running on docker images. Details  refer github doc for Oracle K8S manual installation  . Sometimes we need to add/modify starting arguments of kubernetes core components. ie we need to add TaintBasedEvictions=true for kube-controller-manager component to enable alpha feature. Or we need to add argument for etcd component.

Solution:

    By default, the  manifests files are in master node in  /etc/kubernetes/manifests .You would see these 4 yaml files. Backup the files and do the changes and restart kubernetes cluster.
etcd.yaml  kube-apiserver.yaml  kube-controller-manager.yaml  kube-scheduler.yaml

Where To Find kube-controller-manager Cmd from Kubernetes Cluster

Requirement:

   We need to find  kube-controller-manager file from Kubernetes Cluster which is running on docker images.  refer github doc for Oracle K8S manual installation
    All core binaries are stored inside the docker images.

Solution:

Find the controller docker instance

#docker ps |grep controller
7fc8302ccfe3        887b8144f94f                                                         "kube-controller-man…"   15 hours ago        Up 15 hours                             k8s_kube-controller-manager_kube-controller-manager-instance-cas-mt2_kube-system_d739245871cdd71020650b11ac854d60_0

docker exec into the docker instance and find kube-controller-manager

#docker exec -it k8s_kube-controller-manager_kube-controller-manager-instance-cas-mt2_kube-system_d739245871cdd71020650b11ac854d60_0 /bin/bash

bash-4.2# which kube-controller-manager

/usr/local/bin/kube-controller-manager

Use docker cp to copy the file out of docker instance .

#docker cp k8s_kube-controller-manager_kube-controller-manager-instance-cas-mt2_kube-system_d739245871cdd71020650b11ac854d60_0:/usr/local/bin/kube-controller-manager /bin/

Golang OCI SDK Delete and Download Files Into OCI Object Storage

See details in Github link

Golang OCI SDK Create Bucket and Upload Files Into OCI Object Storage

See details in Github link

How To Run Tcpdump With Logs Rotating

Requirement:

    We need to get tcp traffic on busy systems to diagnose the network related issues.  Tcpdump is a great tool but it also dumps huge amount of data which fill up disk easily.

Solution:

tcpdump has rotation built in. Use below command:
-C  8000*1,000,000 byet --> around 8G each file size
-W total 9 files to keep

nohup tcpdump -i bond0 -C 8000 -W 9 port 5801 -w tcpdump-$(hostname -s).pcap -Z root &