Script to get Kubeval

get-kubeval

#!/usr/bin/env bash

: ${BINARY_NAME:="kubeval"}
: ${USE_SUDO:="true"}
: ${DEBUG:="false"}
: ${KUBEVAL_INSTALL_DIR:="/usr/local/bin"}

HAS_CURL="$(type "curl" &> /dev/null && echo true || echo false)"
HAS_WGET="$(type "wget" &> /dev/null && echo true || echo false)"

# initArch discovers the architecture for this system.
initArch() {
  ARCH=$(uname -m)
  case $ARCH in
    armv5*) ARCH="armv5";;
    armv6*) ARCH="armv6";;
    armv7*) ARCH="arm";;
    aarch64) ARCH="arm64";;
    x86) ARCH="386";;
    x86_64) ARCH="amd64";;
    i686) ARCH="386";;
    i386) ARCH="386";;
  esac
}

# initOS discovers the operating system for this system.
initOS() {
  OS=$(echo `uname`|tr '[:upper:]' '[:lower:]')

  case "$OS" in
    # Minimalist GNU for Windows
    mingw*) OS='windows';;
  esac
}

# runs the given command as root (detects if we are root already)
runAsRoot() {
  local CMD="$*"

  if [ $EUID -ne 0 -a $USE_SUDO = "true" ]; then
    CMD="sudo $CMD"
  fi

  $CMD
}

# verifySupported checks that the os/arch combination is supported for
# binary builds, as well whether or not necessary tools are present.
verifySupported() {
  local supported="darwin-amd64\nlinux-386\nlinux-amd64\nlinux-arm\nlinux-arm64\nlinux-ppc64le\nlinux-s390x\nwindows-amd64"
  if ! echo "${supported}" | grep -q "${OS}-${ARCH}"; then
    echo "No prebuilt binary for ${OS}-${ARCH}."
    echo "To build from source, go to https://github.com/instrumenta/kubeval"
    exit 1
  fi

  if [ "${HAS_CURL}" != "true" ] && [ "${HAS_WGET}" != "true" ]; then
    echo "Either curl or wget is required"
    exit 1
  fi
}

# checkDesiredVersion checks if the desired version is available.
checkDesiredVersion() {
  if [ "x$DESIRED_VERSION" == "x" ]; then
    # Get tag from release URL
    local latest_release_url="https://github.com/instrumenta/kubeval/releases"
    if [ "${HAS_CURL}" == "true" ]; then
      TAG=$(curl -Ls $latest_release_url | grep 'href="/instrumenta/kubeval/releases/tag/0.[0-9]*.[0-9]*\"' | grep -v no-underline | head -n 1 | cut -d '"' -f 2 | awk '{n=split($NF,a,"/");print a[n]}' | awk 'a !~ $0{print}; {a=$0}')
    elif [ "${HAS_WGET}" == "true" ]; then
      TAG=$(wget $latest_release_url -O - 2>&1 | grep 'href="/instrumenta/kubeval/releases/tag/0.[0-9]*.[0-9]*\"' | grep -v no-underline | head -n 1 | cut -d '"' -f 2 | awk '{n=split($NF,a,"/");print a[n]}' | awk 'a !~ $0{print}; {a=$0}')
    fi
  else
    TAG=$DESIRED_VERSION
  fi
}

# checkKubevalInstalledVersion checks which version of kubeval is installed and
# if it needs to be changed.
checkKubevalInstalledVersion() {
  if [[ -f "${KUBEVAL_INSTALL_DIR}/${BINARY_NAME}" ]]; then
    local version=$("${KUBEVAL_INSTALL_DIR}/${BINARY_NAME}" --version | grep Version | awk '{print $2}')
    if [[ "$version" == "$TAG" ]]; then
      echo "Kubeval ${version} is already ${DESIRED_VERSION:-latest}"
      return 0
    else
      echo "Kubeval ${TAG} is available. Changing from version ${version}."
      return 1
    fi
  else
    return 1
  fi
}

# downloadFile downloads the latest binary package
downloadFile() {
  KUBEVAL_DIST="kubeval-$OS-$ARCH.tar.gz"
  DOWNLOAD_URL="https://github.com/instrumenta/kubeval/releases/download/$TAG/$KUBEVAL_DIST"
  KUBEVAL_TMP_ROOT="$(mktemp -dt kubeval-installer-XXXXXX)"
  KUBEVAL_TMP_FILE="$KUBEVAL_TMP_ROOT/$KUBEVAL_DIST"
  echo "Downloading $DOWNLOAD_URL"
  if [ "${HAS_CURL}" == "true" ]; then
    curl -SsL "$DOWNLOAD_URL" -o "$KUBEVAL_TMP_FILE"
  elif [ "${HAS_WGET}" == "true" ]; then
    wget -q -O "$KUBEVAL_TMP_FILE" "$DOWNLOAD_URL"
  fi
}

# installFile installs the Kubeval binary.
installFile() {
  KUBEVAL_TMP="$KUBEVAL_TMP_ROOT/$BINARY_NAME"
  mkdir -p "$KUBEVAL_TMP"
  tar xf "$KUBEVAL_TMP_FILE" -C "$KUBEVAL_TMP"
  KUBEVAL_TMP_BIN="$KUBEVAL_TMP/$BINARY_NAME"
  echo "Preparing to install $BINARY_NAME into ${KUBEVAL_INSTALL_DIR}"
  runAsRoot cp "$KUBEVAL_TMP_BIN" "$KUBEVAL_INSTALL_DIR/$BINARY_NAME"
  echo "$BINARY_NAME installed into $KUBEVAL_INSTALL_DIR/$BINARY_NAME"
}

# fail_trap is executed if an error occurs.
fail_trap() {
  result=$?
  if [ "$result" != "0" ]; then
    if [[ -n "$INPUT_ARGUMENTS" ]]; then
      echo "Failed to install $BINARY_NAME with the arguments provided: $INPUT_ARGUMENTS"
      help
    else
      echo "Failed to install $BINARY_NAME"
    fi
    echo -e "\tFor support, go to https://github.com/instrumenta/kubeval."
  fi
  cleanup
  exit $result
}

# testVersion tests the installed client to make sure it is working.
testVersion() {
  set +e
  KUBEVAL="$(command -v $BINARY_NAME)"
  if [ "$?" = "1" ]; then
    echo "$BINARY_NAME not found. Is $KUBEVAL_INSTALL_DIR on your "'$PATH?'
    exit 1
  fi
  set -e
}

# help provides possible cli installation arguments
help () {
  echo "Accepted cli arguments are:"
  echo -e "\t[--help|-h ] ->> prints this help"
  echo -e "\t[--version|-v <desired_version>] . When not defined it fetches the latest release from GitHub"
  echo -e "\te.g. --version 0.15.0"
  echo -e "\t[--no-sudo]  ->> install without sudo"
}

# cleanup temporary files
cleanup() {
  if [[ -d "${KUBEVAL_TMP_ROOT:-}" ]]; then
    rm -rf "$KUBEVAL_TMP_ROOT"
  fi
}

# Execution

#Stop execution on any error
trap "fail_trap" EXIT
set -e

# Set debug if desired
if [ "${DEBUG}" == "true" ]; then
  set -x
fi

# Parsing input arguments (if any)
export INPUT_ARGUMENTS="${@}"
set -u
while [[ $# -gt 0 ]]; do
  case $1 in
    '--version'|-v)
       shift
       if [[ $# -ne 0 ]]; then
           export DESIRED_VERSION="${1}"
       else
           echo -e "Please provide the desired version. e.g. --version 0.15.0"
           exit 0
       fi
       ;;
    '--no-sudo')
       USE_SUDO="false"
       ;;
    '--help'|-h)
       help
       exit 0
       ;;
    *) exit 1
       ;;
  esac
  shift
done
set +u

initArch
initOS
verifySupported
checkDesiredVersion
if ! checkKubevalInstalledVersion; then
  downloadFile
  installFile
fi
testVersion
cleanup