istio install script for kubernetes

istio-install.sh

#!/bin/sh

## Download istio version
download() {
    OS="$(uname)"
    if [ "x${OS}" = "xDarwin" ] ; then
    OSEXT="osx"
    else
    OSEXT="linux"
    fi

    # Determine the latest Istio version by version number ignoring alpha, beta, and rc versions.
    if [ "x${ISTIO_VERSION}" = "x" ] ; then
    ISTIO_VERSION="$(curl -sL https://github.com/istio/istio/releases | \
                    grep -o 'releases/[0-9]*.[0-9]*.[0-9]*/' | sort --version-sort | \
                    tail -1 | awk -F'/' '{ print $2}')"
    ISTIO_VERSION="${ISTIO_VERSION##*/}"
    fi

    LOCAL_ARCH=$(uname -m)
    if [ "${TARGET_ARCH}" ]; then
        LOCAL_ARCH=${TARGET_ARCH}
    fi

    case "${LOCAL_ARCH}" in 
    x86_64)
        ISTIO_ARCH=amd64
        ;;
    armv8*)
        ISTIO_ARCH=arm64
        ;;
    aarch64*)
        ISTIO_ARCH=arm64
        ;;
    armv*)
        ISTIO_ARCH=armv7
        ;;
    amd64|arm64)
        ISTIO_ARCH=${LOCAL_ARCH}
        ;;
    *)
        echo "This system's architecture, ${LOCAL_ARCH}, isn't supported"
        exit 1
        ;;
    esac

    if [ "x${ISTIO_VERSION}" = "x" ] ; then
    printf "Unable to get latest Istio version. Set ISTIO_VERSION env var and re-run. For example: export ISTIO_VERSION=1.0.4"
    exit;
    fi

    NAME="istio-$ISTIO_VERSION"
    URL="https://github.com/istio/istio/releases/download/${ISTIO_VERSION}/istio-${ISTIO_VERSION}-${OSEXT}.tar.gz"
    ARCH_URL="https://github.com/istio/istio/releases/download/${ISTIO_VERSION}/istio-${ISTIO_VERSION}-${OSEXT}-${ISTIO_ARCH}.tar.gz"

    with_arch() {
    printf "\nDownloading %s from %s ...\n" "$NAME" "$ARCH_URL"
    curl -fsLO "$ARCH_URL"
    filename="istio-${ISTIO_VERSION}-${OSEXT}-${ISTIO_ARCH}.tar.gz"
    tar -xzf "${filename}"
    rm "${filename}"
    }

    without_arch() {
    printf "\nDownloading %s from %s ..." "$NAME" "$URL"
    curl -fsLO "$URL"
    filename="istio-${ISTIO_VERSION}-${OSEXT}.tar.gz"
    tar -xzf "${filename}"
    rm "${filename}"
    }

    # Istio 1.6 and above support arch
    ARCH_SUPPORTED=$(echo "$ISTIO_VERSION" | awk  '{ ARCH_SUPPORTED=substr($0, 1, 3); print ARCH_SUPPORTED; }' )
    # Istio 1.5 and below do not have arch support
    ARCH_UNSUPPORTED="1.5"

    if [ "${OS}" = "Linux" ] ; then
    # This checks if 1.6 <= 1.5 or 1.4 <= 1.5
    if [ "$(expr "${ARCH_SUPPORTED}" \<= "${ARCH_UNSUPPORTED}")" -eq 1 ]; then
        without_arch
    else
        with_arch
    fi
    elif [ "x${OS}" = "xDarwin" ] ; then
    without_arch
    else
    printf "\n\n"
    printf "Unable to download Istio %s at this moment!\n" "$ISTIO_VERSION"
    printf "Please verify the version you are trying to download.\n\n"
    exit
    fi

    printf ""
    printf "\nIstio %s Download Complete!\n" "$ISTIO_VERSION"
    printf "\n"
    printf "Istio has been successfully downloaded into the %s folder on your system.\n" "$NAME"
    printf "\n"
}


istio_install(){
    printf "Starting Istio installation"
    printf "\n"
    printf "Installing istioctl"
    printf "\n"
    install $NAME/bin/istioctl /bin/
    printf "Verifying installation"
    printf "\n"
    if type istioctl ;then
        printf "Installation successfull"
    else
        printf "Installation failed"	
        exit
    fi
    printf "Deploying Istio \n"
    istioctl install --set profile=demo

    printf "Enabling istio for default namesapce \n"
    kubectl label namespace default istio-injection=enabled

    printf "Installation successfull. Please redeploy the pods in default namespace to enable istio sidecar \n"
}
download
set -e
istio_install