Kubernetes/Tools

kubectl

Install

#Latest
curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl

# Specific version
$(VER=v1.13.7; ARCH=amd64; curl -LO https://storage.googleapis.com/kubernetes-release/release/$VER/bin/linux/$ARCH/kubectl)
chmod +x ./kubectl; sudo mv ./kubectl /usr/local/bin/kubectl

# Verify, kubectl should not be more than -/+ 1 minor version difference then api-server
kubectl version --short 
Client Version: v1.13.7
Server Version: v1.13.7-gke.8

# Autocompletion
source <(kubectl completion bash); alias k=kubectl; complete -F __start_kubectl k

# Set default namespace
kubectl config set-context $(kubectl config current-context) --namespace=dev

Kubectl-plugins

• krew package manager for kubectl plugins, requires K8s v1.12+
• Available kubectl plugins Github
• kubectl subcommands write your own plugin

Getting help like manpages

$ kubectl --help
$ kubectl get --help
$ kubectl explain --help
$ kubectl explain pod.spec.containers #kubectl knows cluster version, so gives you correct schema details

• kubectl-commands K8s interactive kubectl command reference

Stern

Log tailing and landscape viewing tool. It connects to kubeapi and streams logs from all pods. Thus using this external tool with clusters that have 100ts of containers can be put significant load on kubeapi.

It will re-use kubectl config file to connect to your clusters, so works oob.

Install

# Govendor - this module manager is required
export GOPATH=$HOME/go        # path where go modules can be found, used by 'go get -u <url>'
export PATH=$PATH:$GOPATH/bin # path to the additional 'go' binaries
go get -u github.com/kardianos/govendor  # there will be no output

# Stern (official)
mkdir -p $GOPATH/src/github.com/wercker
cd $GOPATH/src/github.com/wercker
git clone https://github.com/wercker/stern.git && cd stern
govendor sync # there will be no output, may take 2 min
go install    # no output

# Stern install by getting binary direct, no need for govendor
sudo curl -L https://github.com/wercker/stern/releases/download/1.11.0/stern_linux_amd64 -o /usr/local/bin/stern 
sudo chmod +x /usr/local/bin/stern

Help

$ stern
Tail multiple pods and containers from Kubernetes

Usage:
  stern pod-query [flags]

Flags:
      --all-namespaces             If present, tail across all namespaces. A specific namespace is ignored even if specified with --namespace.
      --color string               Color output. Can be 'always', 'never', or 'auto' (default "auto")
      --completion string          Outputs stern command-line completion code for the specified shell. Can be 'bash' or 'zsh'
  -c, --container string           Container name when multiple containers in pod (default ".*")
      --container-state string     If present, tail containers with status in running, waiting or terminated. Default to running. (default "running")
      --context string             Kubernetes context to use. Default to current context configured in kubeconfig.
  -e, --exclude strings            Regex of log lines to exclude
  -E, --exclude-container string   Exclude a Container name
  -h, --help                       help for stern
  -i, --include strings            Regex of log lines to include
      --kubeconfig string          Path to kubeconfig file to use
  -n, --namespace string           Kubernetes namespace to use. Default to namespace configured in Kubernetes context
  -o, --output string              Specify predefined template. Currently support: [default, raw, json] (default "default")
  -l, --selector string            Selector (label query) to filter on. If present, default to ".*" for the pod-query.
  -s, --since duration             Return logs newer than a relative duration like 5s, 2m, or 3h. Defaults to 48h.
      --tail int                   The number of lines from the end of the logs to show. Defaults to -1, showing all logs. (default -1)
      --template string            Template to use for log lines, leave empty to use --output flag
  -t, --timestamps                 Print timestamps
  -v, --version                    Print the version and exit

Usage

stern <pod>
stern --tail 1 busybox -n <namespace> #this is RegEx that matches busybox1|2|etc

kui terminal

kui is a terminal with visualizations, provided by IBM

curl -sL https://raw.githubusercontent.com/IBM/kui/master/tools/install.sh | sh

• kui shell Github

k9s

Install

curl -O k9s_0.8.2_Linux_x86_64.tar.gz https://github.com/derailed/k9s/releases/download/0.8.2/k9s_0.8.2_Linux_x86_64.tar.gz
tar xf k9s_0.8.2_Linux_x86_64.tar.gz --remove-files k9s
sudo install k9s /usr/local/bin

kubecolor

Kubecolor is a bash function that colorizes the output of kubectl get events -w.

# This script is not working
git clone https://github.com/droctothorpe/kubecolor.git ~/.kubecolor
echo "source ~/.kubecolor/kubecolor.bash" >> ~/.bash_profile # (or ~/.bashrc)
source ~/.bash_profile # (or ~/.bashrc)

# You can source this function instead
kube-events() {
    kubectl get events --all-namespaces --watch \
    -o 'go-template={{.lastTimestamp}} ^ {{.involvedObject.kind}} ^ {{.message}} ^ ({{.involvedObject.name}}){{"\n"}}' \
    | awk -F^ \
    -v   black=$(tput setaf 0) \
    -v     red=$(tput setaf 1) \
    -v   green=$(tput setaf 2) \
    -v  yellow=$(tput setaf 3) \
    -v    blue=$(tput setaf 4) \
    -v magenta=$(tput setaf 5) \
    -v    cyan=$(tput setaf 6) \
    -v   white=$(tput setaf 7) \
    '{ $1=blue $1; $2=green $2; $3=white $3; }  1'
}

# Usage
kube-events
kubectl get events -A -w
kubectl get events --all-namespaces --watch -o 'go-template={{.lastTimestamp}} {{.involvedObject.kind}} {{.message}} ({{.involvedObject.name}}){{"\n"}}'

argo-rollouts

Argo Rollouts introduces a new custom resource called a Rollout to provide additional deployment strategies such as Blue Green and Canary to Kubernetes.

Multi-node clusters

On a single machine

• kube-spawn tool for creating a multi-node Kubernetes (>= 1.8) cluster on a single Linux machine
• kubernetes-dind-cluster Kubernetes multi-node cluster for developer of Kubernetes that launches in 36 seconds
• kind is a tool for running local Kubernetes clusters using Docker container “nodes”
• Vagrant full documentation in thsi article

Full cluster provisioning

• kubespray Deploy a Production Ready Kubernetes Cluster
• kops get a production grade Kubernetes cluster up and running

References

• kubectl overview - resources types, Namespaced, kinds K8s docs
• kubetail Bash script that enables you to aggregate (tail/follow) logs from multiple pods into one stream. This is the same as running "kubectl logs -f " but for multiple pods.
• kubectx kubens Kubernetes config switches for context and setting up default namespace
• manages different ver kubectl blog
• kubectl Kubectl Conventions

Cheatsheets

• cheatsheet-kubernetes-A4 by dennyzhang