Vultr private IP addr grabber on boot (assuming private IP is in key 0 or 1 during boot, not very failsafe, but it works for now)

private_ip.sh

#!/bin/bash
vultrPrivateNetworkConfiguration() {
    VULTR_METADATA_LOCATION='/tmp/vultr_metadata.json'

    if [ ! -f /tmp/vultr_metadata.json ]; then
        curl "http://169.254.169.254/v1.json" > $VULTR_METADATA_LOCATION
    else
        echo "VULTR metadata already present, using it"
    fi

    VULTR_JSON_STRING=$(cat $VULTR_METADATA_LOCATION)
    if [ "$VULTR_JSON_STRING" = "" ]; then
        echo "NOT A VULTR SERVER"
        echo $VULTR_JSON_STRING
        exit 1
    fi

    VULTR_INTERNAL_IP=$(cat $VULTR_METADATA_LOCATION | python -c 'import json,sys;obj=json.load(sys.stdin);print [obj["interfaces"][1]["ipv4"]["address"],obj["interfaces"][0]["ipv4"]["address"]][obj["interfaces"][0]["ipv4"]["address"][:3] == '10.']')
    VULTR_INTERNAL_NETMASK=$(cat $VULTR_METADATA_LOCATION | python -c 'import json,sys;obj=json.load(sys.stdin);print [obj["interfaces"][1]["ipv4"]["netmask"],obj["interfaces"][0]["ipv4"]["netmask"]][obj["interfaces"][0]["ipv4"]["netmask"][:3] == '10.']')

    echo "Found internal IP $VULTR_INTERNAL_IP with netmask $VULTR_INTERNAL_NETMASK"

    if ! grep -q -F "$VULTR_INTERNAL_IP" /etc/network/interfaces; then
        echo "VULTR internal IP address not configured"

        if grep -q -F "ens7" /etc/network/interfaces; then
            echo "Cannot add VULTR internal IP, network interface ens7 is already in use"
            exit 2
        fi

        cp /etc/network/interfaces /tmp/network_interfaces_backup
        echo "Backed up network interfaces file"

        cat >> /etc/network/interfaces <<EOL
auto ens7
iface ens7 inet static
    address $VULTR_INTERNAL_IP
    netmask $VULTR_INTERNAL_NETMASK
    mtu 1450
EOL

        ifup ens7

        echo "Successfully configured VULTR internal IP address"
    else
        echo "VULTR already configured"
    fi
}

vultrPrivateNetworkConfiguration