Usage: lambda-storage-calc.sh --region <aws-region>

lamba-storage-calc.sh

#!/bin/bash -e

if [ $# -ne 2 -o ! "$1" = "--region" ]; then
	echo "Usage: ${0##*/} --region <aws-region>" 2>&1
	exit 1
fi

AWS_REGION="$2"
AWS_OPTIONS+=" --region $AWS_REGION --output json"

lambdas=($(aws $AWS_OPTIONS lambda list-functions | jq -r '.Functions[].FunctionName'))

for lambda in "${lambdas[@]}"; do
	aws $AWS_OPTIONS lambda list-versions-by-function --function-name "$lambda" |
		jq -r '.Versions[] | "\(.LastModified)\t\(.Version)\t\(.CodeSize)\t\(.Description)"' | sort |
		awk -v lambda="$lambda" '
			{
				date = $1;
				version = $2;
				size = $3;
				sub("[^\t]+\t[^\t]+\t[^\t]+\t", "");
				description = $0;

				count++;
				overallSize += size;

				if (version == "$LATEST") {
					latest = size;
				}

				printf("\t%s %7s %10d bytes: %s\n", date, version, size, description);
			}

			END {
				if (count > 1) {
					overallSize -= latest;
				}

				v = count == 1 ? "version" : "versions";
				printf("%s - %d %s, %d total bytes\n", lambda, count, v, overallSize);
			}
		' | tac
done

Note that, if necessary, you can pass options to the AWS CLI commands by setting AWS_OPTIONS outside the script, like:

export AWS_OPTIONS='--profile foo --debug'