is there ANY way to execute aws-cli inside AWS Lambda? It doesn't seem to be pre-installed. (I've checked with "which aws" via Node.js child-process, and it didn't exist.)
Now we can use Layers inside Lambda. Bash layer with aws-cli is available at https://github.com/gkrizek/bash-lambda-layer
handler () {
set -e
# Event Data is sent as the first parameter
EVENT_DATA=$1
# This is the Event Data
echo $EVENT_DATA
# Example of command usage
EVENT_JSON=$(echo $EVENT_DATA | jq .)
# Example of AWS command that's output will show up in CloudWatch Logs
aws s3 ls
# This is the return value because it's being sent to stderr (>&2)
echo "{\"success\": true}" >&2
}