update-suggester.sh

#!/bin/bash
set -eu

if [[ ! -z "${DEBUG:-}" ]]; then
    set -x
fi

function project_kube_check() {
    PROJECT=${1:-$(gcloud config get-value project -q)}
    ZONES=$(gcloud --project=$PROJECT --format='value[](zone)' container clusters list | uniq)
    if [[ -n "${ZONES}" ]]; then
        echo "- project: $PROJECT"
    fi
    for ZONE in $ZONES; do
        CLUSTERS=$(gcloud --project=$PROJECT --format='value[](name)' container clusters --zone="$ZONE" list)
        ZONE_CONFIG=$(gcloud --project=$PROJECT --format=json container get-server-config --zone "$ZONE" 2> /dev/null)
        ZONE_VERSION=$(jq -r .validMasterVersions[0] <<< $ZONE_CONFIG)
        if [[ -n "${CLUSTERS}" ]]; then
            echo "  zones:"
            echo "  - name: $ZONE"
            echo "    zone-latest-version: $ZONE_VERSION"
            echo "    clusters:"
        fi

        for CLUSTER in $CLUSTERS; do
            echo "      - name: $CLUSTER"

            CLUSTER_CONFIG=$(gcloud --project=$PROJECT --format=json container clusters describe --zone $ZONE "$CLUSTER")
            MASTER_VERSION=$(jq -r .currentMasterVersion <<< $CLUSTER_CONFIG)
            NODE_VERSION=$(jq -r .currentNodeVersion <<< $CLUSTER_CONFIG)

            echo "        master-version: $MASTER_VERSION"
            MASTER_BEHIND=$(jq -r '.validMasterVersions[]' <(cat <<< $ZONE_CONFIG) | awk '/'$MASTER_VERSION'/{print NR-1}')
            if [[ "${MASTER_BEHIND}" == "0" ]]; then
                echo "        master-version-support: latest"
            else
                if [[ "$MASTER_BEHIND" == 1 || ${MASTER_BEHIND} == 2 ]]; then
                echo "        master-version-support: $MASTER_BEHIND versions behind"
                else
                    echo "        master-version-support: unsupported"
                fi
                SAFE_MASTER_VERSION=$(jq -r '.validMasterVersions[0]' <<< $ZONE_CONFIG)
                echo "        upgade-masters-command: >"
                echo "          gcloud --project=$PROJECT container clusters upgrade $CLUSTER --master --cluster-version=${SAFE_MASTER_VERSION} --zone=$ZONE"
            fi

            echo "        node-version: $NODE_VERSION"
            NODE_BEHIND=$(jq -r '.validNodeVersions[]' <(cat <<< $ZONE_CONFIG) | awk '/'$NODE_VERSION'/{print NR-1}')
            if [[ "${NODE_BEHIND}" == "0" ]]; then
                echo "        node-version-support: latest"
            else
                if [[ "$NODE_BEHIND" == 1 || ${NODE_BEHIND} == 2 ]]; then
                    echo "        node-version-support: $NODE_BEHIND versions behind"
                else
                    echo "        node-version-support: unsupported"
                fi
                SAFE_NODE_VERSION=$(jq -r '.validNodeVersions[0]' <<< $ZONE_CONFIG)
                echo "        upgade-nodes-command: >"
                echo "          gcloud --project=$PROJECT container clusters upgrade $CLUSTER --cluster-version=${SAFE_NODE_VERSION} --zone=$ZONE"
            fi
        done
    done
}

# CLUSTERS=$(gcloud --format='value[](zone)' container clusters list)
if [[ -n "${ALL_PROJECTS:-}" ]]; then
    for PROJECT in $(gcloud projects list --format=json | jq -r '.[].projectId'); do
        project_kube_check $PROJECT
    done
else
    project_kube_check
fi

https://cloud.google.com/kubernetes-engine/docs/tutorials/authenticating-to-cloud-platform

Using google/cloud-sdk image to automate update