How to store images on AWS-S3 automatically?

Instructions:

First you need to ensure that the official AWS-S3 SDK for PHP is installed:

composer require aws/aws-sdk-php

1. Configure Knp-Gaufrette

Place this file under config/packages/knp_gaufrette.yaml:

# config/packages/knp_gaufrette.yaml
knp_gaufrette:
    adapters:
        sylius_image:
            aws_s3:
                service_id: Aws\S3\S3Client
                bucket_name: "%aws.s3.bucket%"
                detect_content_type: true
                options:
                    directory: "media/image"
                    acl: "public-read"
    stream_wrapper: ~

2. Configure Liip-Imagine:

Add this file under config/packages/liip_imagine.yaml in order to make Liip-Imagine aware of AWS S3 storage:

# config/packages/liip_imagine.yaml
liip_imagine:
    loaders:
        aws_s3:
            stream:
                wrapper: gaufrette://sylius_image/
    resolvers:
        aws_s3:
            aws_s3:
                client_config:
                    credentials:
                        key:    "%aws.s3.key%"
                        secret: "%aws.s3.secret%"
                    region: "%aws.s3.region%"
                    version: "%aws.s3.version%"
                bucket: "%aws.s3.bucket%"
                get_options:
                    Scheme: https
                put_options:
                    CacheControl: "max-age=86400"
                cache_prefix: media/cache
    data_loader: aws_s3
    cache: aws_s3

3. Define S3-related parameters and configure final services:

In config/services.yaml:

# config/services.yaml
parameters:
    aws.s3.key: "%env(AWS_S3_KEY)%"
    aws.s3.secret: "%env(AWS_S3_SECRET)%"
    aws.s3.bucket: "%env(AWS_S3_BUCKET)%"
    aws.s3.region: "%env(AWS_S3_REGION)%"
    aws.s3.version: "%env(AWS_S3_VERSION)%"

services:
    # composer require aws/aws-sdk-php
    Aws\S3\S3Client:
        factory: [Aws\S3\S3Client, 'factory']
        arguments:
            -
                version: "%aws.s3.version%"
                region: "%aws.s3.region%"
                credentials:
                    key: "%aws.s3.key%"
                    secret: "%aws.s3.secret%"