An istioctl installer - Easily install istioctl

istioctl-installer.sh

#!/bin/sh

__getLatestVersion(){
  request="$(curl -sI https://github.com/istio/istio/releases/latest | grep "^location")"
  request="${request##*/}"
  echo "$request" | tr -d '\r'
}

__getOperatingSystem(){
  get_system_name="$(uname | tr '[:upper:]' '[:lower:]')"
  case "$get_system_name" in
    darwin)
      readonly HOST_OS="osx"
      readonly EXT="tar.gz"
      readonly ARCH="amd64"
    ;;
    mingw64*)
      readonly HOST_OS="win"
      readonly EXT="zip"
      readonly ARCH="amd64"
    ;;
    linux*)
      readonly HOST_OS="linux"
      readonly EXT="tar.gz"
      readonly ARCH="amd64"
    ;;
    *)
      readonly HOST_OS="unknown"
      return 1
    ;;
  esac
}

__makeIstioHome(){
  readonly ISTIO_HOME="$HOME/.istio"
  mkdir -p "${ISTIO_HOME}"
}

__createDownloadFolder(){
  readonly TEMP_DIR="istio.tmp"
  mkdir -p "./${TEMP_DIR}"  
}

__downloadBinary(){
  readonly VERSION="$(__getLatestVersion)"
  readonly ARTIFACT="istioctl-${VERSION}-${HOST_OS}.${EXT}"
  readonly ARTIFACT_SHA="${ARTIFACT}.sha256"
  readonly ARTIFACT_ENDPOINT="https://github.com/istio/istio/releases/download/${VERSION}"
  readonly ARTIFACT_DOWNLOAD_URL="${ARTIFACT_ENDPOINT}/${ARTIFACT}"
  curl -sL "${ARTIFACT_DOWNLOAD_URL}" -o "./${TEMP_DIR}/${ARTIFACT}"
}

__extractBinary(){
  tar -xf "${TEMP_DIR}/${ARTIFACT}" -C "${TEMP_DIR}"
}

__moveBinaryToIstioHome(){
  mv "${TEMP_DIR}/istioctl" "${ISTIO_HOME}/"
}

__installCleanUp(){
  rm -rf "${TEMP_DIR}"
}

main(){
  if ! __makeIstioHome; then
    printf "Could not create the directory %s/.istio" "$HOME"
    exit 1
  fi
  
  if ! __getOperatingSystem; then
    printf "Could not determine your host operating system."
    exit 1
  fi

  if ! __createDownloadFolder; then
    printf "Could not create the temporary folder %s" "$TEMP_DIR"
    exit 1
  fi
  
  if ! __downloadBinary; then
    printf "Was unable to download the Istio installer package."
    exit 1
  fi

  if ! __extractBinary; then
    printf "Was not able to extract the Istio binary."
    exit  1
  fi

  if ! __moveBinaryToIstioHome; then
    printf "Was not able to move the istioctl binary to ISTIO_HOME"
    exit 1
  fi

  if ! __installCleanUp; then
    printf "Was not able to perform clean up on ./%s" "$TEMP_DIR"
    printf "Try manually deleting it."
  fi

  printf "istioctl %s was successfully downloaded.\n" "$VERSION"
  printf "\n"
  printf "To configure your machine to use istioctl, do one of the following:\n"
  printf "\n"
  printf "  Add ISTIO_HOME To Your PATH\n"
  printf "    export PATH=\"\$PATH:%s\"\n" "$ISTIO_HOME"
  printf "\n"
  printf "  - or -\n"
  printf "\n"
  printf "  Create A Symlink\n"
  printf "    ln -s $ISTIO_HOME/istioctl /usr/local/bin/istioctl\n"
  printf "\n"
  printf "\n"
  printf "Begin the Istio pre-installation verification check by running:\n"
  printf "\n"
  printf "  istioctl verify-install \n"
  printf "\n"
  printf "Need more information? Visit https://istio.io/docs/setup/kubernetes/install/ \n"
  printf "\n"
}

main