Cleanup old Configmaps created by helm.. faster edition

cleanup_old_configmaps_helm.sh

#!/usr/bin/env bash

# Courtesy: https://github.com/helm/helm/issues/2332#issuecomment-336565784
# Enhanced for performance

TARGET_NUM_REVISIONS=10
TARGET_NUM_REVISIONS=$(($TARGET_NUM_REVISIONS+0))

RELEASES=$(kubectl --namespace=kube-system get cm -l OWNER=TILLER -o go-template --template='{{range .items}}{{ .metadata.labels.NAME }}{{"\n"}}{{ end }}' | sort -u)

# create the directory to store backups
mkdir configmaps

for RELEASE in $RELEASES; do
  # get the revisions of this release
  REVISIONS=$(kubectl --namespace=kube-system get cm -l OWNER=TILLER -l NAME=$RELEASE | awk '{if(NR>1)print $1}' | sed 's/.*\.v//' | sort -n)
  NUM_REVISIONS=$(echo $REVISIONS | tr " " "\n" | wc -l)
  NUM_REVISIONS=$(($NUM_REVISIONS+0))

  echo "Release $RELEASE has $NUM_REVISIONS revisions. Target is $TARGET_NUM_REVISIONS."
  if [[ $NUM_REVISIONS -gt $TARGET_NUM_REVISIONS ]]; then
    NUM_TO_DELETE=$(($NUM_REVISIONS-$TARGET_NUM_REVISIONS))
    echo "Will delete $NUM_TO_DELETE revisions"

    TO_DELETE=$(echo $REVISIONS | tr " " "\n" | head -n $NUM_TO_DELETE)

    CM_NAMES=()
    for DELETE_REVISION in $TO_DELETE; do
      CMNAME=$RELEASE.v$DELETE_REVISION
      CM_NAMES+=(${CMNAME})
    done

    kubectl -n kube-system get cm ${CM_NAMES[@]} -o yaml > configmaps/${RELEASE}.yaml
    kubectl -n kube-system delete cm ${CM_NAMES[@]}
  fi
done