Day 4: Amazon S3 – Buckets, Objects, Storage Classes, and Keeping Data Private
Day 4 of my 90-day AWS challenge: how Amazon S3 stores files as objects in buckets, the main storage classes, and how I created a bucket, uploaded a file, and kept it secure.
Recap of Day 3
Yesterday I launched my first EC2 instance. Servers need somewhere to keep files, backups, and website assets, so today I'm learning Amazon S3.
What is Amazon S3?
S3 (Simple Storage Service) is AWS's object storage service. You can store and retrieve any amount of data, such as images, videos, documents, logs, and backups, from anywhere on the internet. It is designed for 99.999999999% (11 nines) durability, which means your data is extremely unlikely to be lost.
Key concepts
| Concept | What it is |
|---|---|
| Bucket | A container for your objects. The name must be globally unique, and the bucket lives in one Region |
| Object | The file plus its metadata (up to 5 TB each) |
| Key | The unique name of an object inside a bucket, e.g. images/profile.png |
| Storage class | How the data is stored, balancing cost and access speed |
Common storage classes
- S3 Standard: frequently accessed data
- S3 Standard-IA / One Zone-IA: infrequently accessed data at a lower cost
- S3 Glacier classes: long-term archives at the lowest cost, with slower retrieval
- S3 Intelligent-Tiering: automatically moves data between tiers based on access patterns
Security basics
- Block Public Access is on by default. Keep it on unless you truly need a public bucket
- IAM policies and bucket policies control who can read or write
- Encryption at rest is applied to new objects by default
- Versioning keeps older versions of an object, so accidental deletes and overwrites can be recovered
What I practiced today
- Created a bucket with a unique name in my chosen Region
- Kept Block Public Access turned on
- Uploaded a file and viewed its properties
- Enabled versioning and uploaded a new version of the same file
- Deleted the objects and the bucket when I was done
Key takeaways
- S3 stores objects, not files on a disk, and it is not meant to be a boot drive for a server
- Keep buckets private by default; many data leaks come from public buckets
- Choose the storage class that matches how often you access the data
Up next: Day 5
Amazon VPC: understanding networking in AWS.
Learning AWS too? Follow along and share what you're building. #90DaysOfAWS
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