wait-for-dns.sh

#!/bin/bash

############################################################################################
#
# Script used testing access to an Azure storage account with a private endpoint
#
############################################################################################

#
# Argument parsing
#

function show_usage() {
    echo "wait-for-dns.sh"
    echo
    echo "Wait for DNS name to be resolvable to an IP address"
    echo
    echo -e "\t--name\t(Required) The DNS name to query"
}

# Parameter defaults:
DNS_NAME="" 
# Process switches:
while [[ $# -gt 0 ]]
do
    case "$1" in
        --name)
            DNS_NAME=$2
            shift 2
            ;;
        *)
            echo "Unexpected '$1'"
            show_usage
            exit 1
            ;;
    esac
done

echo $DNS_NAME
if [[ -z "$DNS_NAME" ]]; then 
    show_usage
    exit 1
fi

# TODO - pass this into the script for clarity!
PUBLIC_DNS_NAME=$(echo $DNS_NAME | sed "s/privatelink\.//")
STORAGE_ACCOUNT_NAME=$(echo $DNS_NAME | sed "s/\..*//")

#
# Lookup the IP address...
#
echo "Looking up IP address for $DNS_NAME"
echo "(using public name: $PUBLIC_DNS_NAME)"
echo "(using storage account name: $STORAGE_ACCOUNT_NAME)"
for i in {1..24}; do
    echo "Attempt $i..."
    PRIVATE_IP_ADDRESS=$(host -t A $DNS_NAME | awk '/has address/{print $NF; exit}');
    PUBLIC_IP_ADDRESS=$(host -t A $PUBLIC_DNS_NAME | awk '/has address/{print $NF; exit}');
    if [[ -n $PRIVATE_IP_ADDRESS ]]; then
        echo "Got IP Address $PRIVATE_IP_ADDRESS for name $DNS_NAME"
        echo "Got IP Address $PUBLIC_IP_ADDRESS for name $PUBLIC_DNS_NAME"

        if [[ "$PRIVATE_IP_ADDRESS" == "$PUBLIC_IP_ADDRESS" ]]; then
            echo "Addresses match - done."
            echo "Test az container list..."
            echo "'$STORAGE_ACCOUNT_NAME'"
            AZ_RESULT=$(az storage container list --account-name $STORAGE_ACCOUNT_NAME > /dev/null; echo $?)
            echo "result: '$AZ_RESULT'"
            if [[ "$AZ_RESULT" == "0" ]]; then
                echo "az cli test passed - done!"               
                exit 0
            else 
                echo "az cli test failed"
            fi
        else 
            echo "Addresses don't match"
        fi
    else 
        echo "Didn't get private IP address"
    fi
    sleep 5s
done

echo "Failed to get IP address for $DNS_NAME"
exit 1