kubectl-switch

#!/bin/bash

# If only one argument is given when calling this script, we do a namespace switch.
# If a second argument exists when calling this script, we do a cluster switch.
# When switching clusters, alert the user if that cluster is not found.

# The trap provides the current context on exit. The context names are sorted to provide consistency.
LRED=$(echo -en '\033[01;31m')
RESTORE=$(echo -en '\033[0m')
trap 'CURRENT_CONTEXT=$(kubectl config current-context) && echo && kubectl config get-contexts | head -n1 && kubectl config get-contexts | sed 1d | sort --key=1 -b | sed "s|\*\(.*\)${CURRENT_CONTEXT}\(.*\)$|${LRED}\*\1${CURRENT_CONTEXT}\2${RESTORE}|g"' 0 1 3 15

# Usage
usage() { echo -e "# Usage\n\tPrompt for Clusters: kubectl switch cluster -l\n\tSwitch Namespace: kubectl switch <namespace>\n\tSwitch Cluster: kubectl switch cluster <cluster_name>\n" && exit 0; }
[ $# -eq 0 ] || [[ "$1" == "-h" ]] || [[ "$1" == "--help" ]] && usage

NAMESPACE="$1"
CLUSTER="$2"

### List the clusters to choose from
function list_clusters() {
    IFS=$'\n'
    CLUSTERS=($(kubectl config get-clusters | grep -v NAME | sort))
    count=1

    for i in ${!CLUSTERS[@]}; do
        echo "[$count]: ${CLUSTERS[$i]}"
        let count=count+1
    done

    echo; read -p "Enter the number of the cluster to use: " SELECTION
    SELECTION=$(($SELECTION - 1))
    CLUSTER="${CLUSTERS[$SELECTION]}"

    switch_cluster
}

### Switch cluster context
function switch_cluster() {
  # Verify it's a valid cluster name with kubectl
    CLUSTER_NAME=$(kubectl config get-clusters | grep "$CLUSTER$")
  # Fallback in case the user has renamed their context for the cluster.
    if [ -z "${CLUSTER_NAME}" ]; then
      # Allow fuzzying on context name
        CLUSTER_NAME=($(kubectl config get-contexts -o name | grep $CLUSTER))
      # If globbing gives more than one match, discard those and look for an exact match
        if [ ${#CLUSTER_NAME[@]} -ne 1 ]; then
            unset CLUSTER_NAME
            CLUSTER_NAME=$(kubectl config get-contexts -o name | grep $CLUSTER$)
        fi
      # If all lookups have failed, exit 1.
        if [ -z "${CLUSTER_NAME}" ]; then
            RED=$(echo -en '\033[00;31m')
            YELLOW=$(echo -en '\033[00;33m')
            RESTORE=$(echo -en '\033[0m')
            echo -e "\n${RED}Error on lookup. Cannot find:${YELLOW} $CLUSTER${RESTORE}\n"
            exit 1
        fi
    fi
    CLUSTER="$CLUSTER_NAME"
    kubectl config use-context $CLUSTER >/dev/null 2>&1
    if [ $? -ne 0 ]; then
        CLUSTER=$(kubectl config get-contexts | grep " $CLUSTER " | sed 's|\*||g' | awk '{print $1}') >/dev/null 2>&1
        kubectl config use-context $CLUSTER >/dev/null 2>&1
    fi
    [ $? -ne 0 ] && echo -e "\n####### TYPO!  Please re-check the spelling for cluster: $2" && exit 1

}


### Switch namespace for current context
function switch_namespace() {
    kubectl config set-context $(kubectl config current-context) --namespace="$NAMESPACE" 1>/dev/null
    exit 0
}


if [[ "$@" =~ " -l" ]]; then
    list_clusters
elif [[ "$@" =~ "cluster" ]]; then
    switch_cluster
elif [[ ! "$@" =~ "cluster" ]]; then
    switch_namespace
fi