AWS Deep Dive

author: Nathan Acks
date: 2022-06-06

AWS Essentials

More notes today from Linux Academy’s “AWS Essentials” YouTube playlist.

Object Lifecycles

AWS Essentials: Object Lifecycles (YouTube)

An “object lifecycle” is a set of rules in S3 that migrate objects between storage classes (or even delete them!) based on the age of an object.

Permissions

AWS Essentials: Permissions (YouTube)

Permissions granted to (non-admin) users (at the individual/group level) or resources (at the individual/role level) only apply to using a service in AWS. Permissioning for object create in a given service is still handled at the object level.

For example, giving a group full access to S3 doesn’t give the members of that group access to any of the buckets created in S3 by other users in the account - that access must be applied at the bucket level.

Note that making a bucket public is not enough to make its contents viewable outside of the AWS account - there still needs to be a permission grant to “everyone” that makes the object/folder/etc. downloadable. (My take-away from this is that making an S3 bucket public is essentially changing the definition of “everyone” from “everyone in the current AWS account” to “everyone everyone”.)

Object Versioning

AWS Essentials: Object Versioning (YouTube)

Note that suspending versioning doesn’t delete old versions - it simply stops the creation of new object versions in that bucket. (And yes - once you’ve enabled versioning for a bucket, you cannot disable it. Versioning can only be “suspended”.)

Be aware that new object versions do not inherit the original version’s storage class - that’s set per object (even per versioned object).

EC2 Basics

AWS Essentials: EC2 Basics (YouTube)

EC2 = Elastic Compute Cloud

In addition to “on-demand” and “reserved” instances, Amazon also has “spot” instances that are sold using an auction-like mechanism. The “spot” price fluctuates based on how much capacity is currently unused in EC2. When the spot price is at or below your “bid”, you automatically get a spot instance configured and provisioned (at the cost is your bid). When the spot price exceeds your bid, your instance is automatically terminated and re-allocated to users with a higher bid. So spot instances can be cheap, but access is unreliable (and becomes more so during peak usage periods).

Amazon Machine Images (AMIs)

AWS Essentials: Amazon Machine Images (AMIs) (YouTube)

An AMI is basically just a templated VM with some configuration knobs. (Mostly these knobs are about “pre-installing” applications and setting up desired configurations. In practice, this translates to kicking off scripts during the AMI’s first run that actually install and configure things for you.)