Try pinging Localstack and then reading and writing a file to/from a bucket on (Localstack or AWS) S3

ping_read_write_localstack_s3.sh

#!/bin/bash

PORT=4572

# Ping Localstack up to 10 times every 0.5s.
# Using docker-wait wouldn't work as the server
# runs as blocking process and never terminates.
echo "Waiting for Localstack to be up..."
while ! nc -z localhost $PORT; do
  sleep 0.5
  ((c++)) && ((c==10)) && c=0 && exit 1
done
echo "Localstack is up and running on the port $PORT!"

# Check writing permissions on the bucket.
# Localstack takes quite some time (3-4s) to finish
# spawning all of its components and execute the bucket
# creation in `config/docker/localstack`. In the meanwhile,
# it will still be pingable but the bucket won't be created
# if addressed too soon. So we wait for them 1s up to 15 times.
try_s3_write() {
  bucket_status=$(AWS_ACCESS_KEY_ID=test AWS_SECRET_ACCESS_KEY=test \
    aws --endpoint-url=http://localhost:$PORT \
    s3api put-object --key test --body test_file --bucket test-bucket 2>&1)
  echo "${bucket_status}" | grep -q 'ETag'
  return $?
}

touch test_file

echo "Testing S3 bucket permission on Localstack"
while ! try_s3_write; do
  sleep 1
  ((c++)) && ((c==15)) && c=0 && exit 1
done
echo "Writing on Localstack S3 successful!"

try_s3_read() {
  bucket_status=$(AWS_ACCESS_KEY_ID=test AWS_SECRET_ACCESS_KEY=test \
    aws --endpoint-url=http://localhost:$PORT \
    s3api get-object --key test --bucket test-bucket /dev/stdout | sed 1q)
  echo "${bucket_status}" | grep -q 'hello'
  return $?
}

if [ ! try_s3_read ]; then echo "read failed"; else echo "read succeeded"; fi &