AWS S3 : Key Concepts

Simple Storage Service S3:

Simple Storage Service, Object based storage, Allow us to upload files. store multiple files from 0 bytes to 5 TB. Threre is unlimited storage.  Files are stored in buckets (folders).

Universal namespace, Names must be unique globally
Sample link: https<> region.aws./bucket_name. It's always unique.
Not suitable to install Operating system on.Not suitable to host DB on S3.
Can activate/ turn on  MFA (Multi factor authentication )Delete.
200 response code after upload, it is successful.
Can turn on
 Key (name of the object), value (data ie, sequence of bytes) and Version id (for versioning )
Metadata (data about data)

Object metadata is optional.System metadata mantained by s3.
Sub resources : Access control Lists (permission at bucket level and object level), Torrent
S3 can also be used for hosting static websites, by enabling bucket hosting.
myDomain.com->Redirected to DNS based URL
Max PUT rate allowed is 3500 PUTs/sec
Data Consistency:
  PUTS  of new object: Read after write consistency
  Overwrite PUTS and DELETS : Eventual consistency .Can take some time  to propagate. Might get older object for a moment, about a sec.

Permissions/Control Access to buckets: 
 Can be done at bucket level and object level(after turning on permissions on bucket Make public.)

Make public
Use Bucket ACL or Bucket Policies.
By default all newly created buckets are private.

S3 Pricing:
Storage, # of requests, Storage management pricing, Data transfer pricing, Transfer acceleration, Cross region Replication pricing. 

S3 Encryption:

-Encryption in Transit (https: ssl/tls)

-Encryption at Rest (server side) ,apply AES-256

S3 SSE- S3 manages both data and master keys (server side managed encryption)
SSE-KMS, AWS manages data keys, you manage the master key in KMS.
SSE- C : Client manages the keys.

S3 Versioning:

Stores all version of an object including all writes and even if you delete an object.A backup tool

Once versioning is enabled it cannot be deleted only suspended,

Can enable multifactor delete capability.

If versioning enabled. Even if we delete, it can be restored. Delete will add one more entry with delete marker addd and 0 size.

S3 Lifecycle Management:

Create a new life cycle rule. 
Applied at bucket level

Automating moving your objects between the different storage tiers

Versioning must be enabled on both source and destination buckets.

Regions must be unique.

The existing and delete markers/ deleted files are not replicated.

S3 transfer Acceleration:

User upload the files to edge location

Uploading files to edge locations rather than buckets. Then AWS transfer it to s3.

CORS configuration:
Allowed methods GET/PUT/POST/DELETE/HEAD
Bucket Replication:
Bucket->Management-> Replication->Add Rule- (Enable versioning) src bucket -> dest bucket.
You can also give access to another account users.

To restrict accidental deletion: - Enable MF authorisation and versioning.
To avoid other websites uses, change to signed url with expiry dates.
Use cross region replication for complicance requirements.
Use logical or sequential naming patterns in S3 object naming without any performance implications
S3 supports GZIP  and BZIP2 compression.
S3 versioning: each versioning can have different retention period.

you cannot connect to an Amazon S3 static website using HTTPS (only HTTP)