dehelm

dehelm

#!/bin/bash

source "$(dirname "$0")/include-color.sh"
source "$(dirname "$0")/include-log.sh"

function usage {
  echo -e "
Usage: ${0#\.\/} [ARGUMENT...][OPPERAND]

Download, extract and render the contents of a Helm chart into to an opinionated,
Kustomize-friendly directory structure 

Options:
  -h, --help                           print this help message

Arguments:
  -c, --chart                          Helm chart to fetch
  -n, --namespace                      Kubernetes namespace to render the Helm chart to
  -o, --overlays                       comma-separated list of overlay directories to create (e.g. dev,test,prod)
  -r, --repo                           chart repository url where to locate the requested chart
  -v, --version                        chart version
  -b, --base                           location of the 'base' directory (overrides -n, --namespace)
"
  exit
}

function main {

  # check that a Helm chart has been specified
  if [ -z "$dehelm_chart" ]; then
    log "ER" "missing arguments '-c, --chart'"
    usage
    exit 1
  fi

  # set defaults if not passed
  if [ -z "$dehelm_namespace" ]; then
    dehelm_namespace="default"
  fi

  if [ -z "$dehelm_repo" ]; then
    dehelm_repo="https://kubernetes-charts.storage.googleapis.com"
  fi

  if [ -z "$dehelm_version" ]; then
    dehelm_version=$(helm inspect chart --repo ${dehelm_repo} ${dehelm_chart} | grep -w "version:" | cut -d ' ' -f 2)
    log "IN" "assuming latest major Helm chart version '${dehelm_version}'"
  fi

  if [ -z "$dehelm_base" ]; then
    dehelm_base="../manifests/${dehelm_namespace}/${dehelm_chart}/base"
  fi

  # make a '.helm' directory to serve as a working directory and store
  # the chart's 'values.yaml' file
  mkdir -p ${dehelm_base}/.helm

  # fetch the Helm chart and extract it
  helm fetch \
    --untar \
    --untardir ${dehelm_base}/.helm \
    --repo ${dehelm_repo} \
    --version ${dehelm_version} \
    ${dehelm_chart}

  if [ $? -ne 0 ]; then
    log "ER" "failed to fetch Helm chart"
    exit 1
  fi

  # if a 'values.yaml' file does not already exist, copy it from the Helm chart
  if [ ! -f "${dehelm_base}/.helm/values.yaml" ]; then
    cp ${dehelm_base}/.helm/${dehelm_chart}/values.yaml ${dehelm_base}/.helm/values.yaml
  else
    log "WR" "not overwriting 'values.yaml' found at '${dehelm_base}/.helm/values.yaml'"
  fi

  # render the Helm chart to 'kubectl' compatible YAML
  helm template \
    --values ${dehelm_base}/.helm/values.yaml \
    --output-dir ${dehelm_base} \
      ${dehelm_base}/.helm/${dehelm_chart}
  
  mv ${dehelm_base}/${dehelm_chart}/templates/* ${dehelm_base}/
  
  cd ${dehelm_base} # try to prevent nasty accidents with `rm -rf`
  rm -rf ${PWD}/${dehelm_chart}
  cd - >/dev/null # bounce back to where we were before

  # create Kustomize directory structure
  mkdir -p ${dehelm_base}/.kustomize/patches

  cat << EOF > ${dehelm_base}/.gitignore
/*
!.gitignore
!.helm/
.helm/*
!.helm/values.yaml
!.kustomize
!kustomization.yaml

EOF

  cat << EOF > ${dehelm_base}/kustomization.yaml
apiVersion: v1beta1
kind: Kustomization

namespace: ${dehelm_namespace}

EOF

  # create overlays
  if [ ! -z "$dehelm_overlays" ]; then
    for overlay in $(echo $dehelm_overlays | tr ',' '\n'); do
      log "IN" "creating overlay '${overlay}'"
      mkdir -p ${dehelm_base}/../overlays/${overlay}
      #TODO: Automatically add kustomization.yaml with base (../base) defined
    done
  fi
}

# check that 'helm' is installed
if ! which helm >/dev/null; then 
  log "ER" "could not find 'helm' installation"
fi

# show usage if no arguments are passed
if [ "$1" = "" ]; then
  usage
fi

# command line parameters
while [ "$1" != "" ]; do
  case $1 in
      -c | --chart )              shift
                                  dehelm_chart=$1
                                  ;;

      -n | --namespace )          shift
                                  dehelm_namespace=$1
                                  ;;

      -o | --overlays )           shift
                                  dehelm_overlays=$1
                                  ;;

      -r | --repo )               shift
                                  dehelm_repo=$1
                                  ;;

      -v | --version )            shift
                                  dehelm_version=$1
                                  ;;

      -b | --base )               shift
                                  dehelm_base=$1
                                  ;;

      -h | --help | * )           usage
  esac
  shift
done

main

include-color.sh

#!/bin/bash

# ANSI color codes
IN="\033[36m" # Cyan
ER="\033[31m" # Red
WR="\033[33m" # Yellow
OK="\033[32m" # Green
DB="\033[35m" # Purple
NC="\033[0m"  # No color

include-log.sh

#!/bin/bash

function log {
  TYP=$1 # ER, WR, OK
  MSG=$2
  NOW=$(date +"%m-%d-%Y %T")

  case "$TYP" in
    "IN")
      echo -e "${IN}${0#\.\/}: [${NOW}] INFO ${MSG}${NC}"
    ;;
    "ER")
      echo -e "${ER}${0#\.\/}: [${NOW}] ERROR ${MSG}${NC}"
    ;;
    "WR")
      echo -e "${WR}${0#\.\/}: [${NOW}] WARNING ${MSG}${NC}"
    ;;
    "OK")
      echo -e "${OK}${0#\.\/}: [${NOW}] SUCCESS ${MSG}${NC}"
    ;;
    "DB")
      echo -e "${DB}${0#\.\/}: [${NOW}] DEBUG ${MSG}${NC}"
    ;;
    *)
      echo -e "${DB}${0#\.\/}: [${NOW}] DEBUG Something went wrong when trying to print this error:
           >>> TYP(${TYP}),
           >>> MSG($MSG),
           >>> NOW(${NOW})${NC}"
    ;;
esac
}