clean-old-cm.sh

#!/usr/bin/env bash

set -eu

# defaulting the context to a blank string just uses the currently configured context
context=${1:-""}

max_number_rev=10
declare -a namespaces=( "kube-system" )

for namespace in "${namespaces[@]}"
do
  releases=$(kubectl --context="$context" --namespace=$namespace get cm -l OWNER=TILLER -o go-template --template='{{range .items}}{{ .metadata.labels.NAME }}{{"\n"}}{{ end }}' | sort -u)

  for release in $releases
  do
    # get the revisions of this release
    revisions=$(kubectl --context="$context" --namespace=$namespace get cm -l OWNER=TILLER -l STATUS=SUPERSEDED -l NAME=$release --no-headers | awk '{if(NR>1)print $1}' | sed 's/.*\.v//' | sort -n)
    num_revisions=$(echo $revisions | tr " " "\n" | wc -l)

    echo "release $release has $num_revisions revisions. Max number is $max_number_rev."
    if [[ $num_revisions -gt $max_number_rev ]]; then
      num_to_delete=$(($num_revisions-$max_number_rev))
      echo "Will delete $num_to_delete revisions"

      to_delete=$(echo $revisions | tr " " "\n" | head -n $num_to_delete)

      for del_rev in $to_delete
      do
        cm=$release.v$del_rev
        echo "Deleting $cm"
        kubectl --context="$context" --namespace=$namespace delete cm $cm
      done
    fi
  done
done