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Chapter 16 - Conclusions
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NoteStudied by 1348 peopleallemand
NoteStudied by 131 peopleChapter 14: Injury and Illness
NoteStudied by 6 peopleV. Scientific Revolution (Chapter 16)
NoteStudied by 3 peopleINTRODUCTION: MATTER, ENERGY, AND MEASUREMENT
NoteStudied by 38 peopleSection 8 - High Availability & Scalability: ELB & ASGV
- Scalability & High Availability
- Scalability means that an application/system can handle greater loads by adapting
- High availability: run instance for the same application across multi AZ
- High availability usually goes hand in hand with horizontal scaling
- Means running your application/system in at least 2 AZs
- The goal is to survive a data center loss
- Can be passive (for RDS Multi AZ), active (for horizontal scaling)
- 2 types:
- Vertical: increasing the size of the instance
- Common for non distributed systems, such as a database
- RDS, ElastiCache are services that can scale vertically
- There's usually a hardware limit to how much you can vertically scale
- Ex: r4.large ‒> r4.4xlarge
- Horizontal: increasing the number of instances/systems for your application
- Auto Scaling Group, Load Balancer
- Implies distributed systems
- Common for web applications/modern applications
- easy to horizontally scale thanks to EC2
- Elastic Load Balancing
- Load Balancers ‒> servers that forward traffic to multiple servers (Ex: EC2 Instances) downstream
- Spread load across multiple downstream instances
- Expose singly point of access (DNS)
- Seamlessly handle failures of downstream instances
- Do Regular health checks to instances
- enable load balancer to know if instances it forwards traffic to are available to reply to requests
- done on port and route (/health is common)
- 200 (Ok)
- Provide SSL termination (HTTPS) for websites
- Enforce stickiness with cookies
- High availability across zones
- Separate public traffic from private traffic
- Elastic Load Balancer ‒> managed load balancer
- AWS guarantees that it will be working
- AWS takes care of upgrades, maintenance, high availability
- AWS provides only a few configuration knobs
- Costs less to setup your own but more effort
- integrated with many AWS offerings
- EC2, EC2 Auto Scaling, ECS, ….
- 4 Types:
- Classic Load Balancer (v1) - CLB: HTTP, HTTPS, TCP, SSL
- Supports TCP (Layer 4), HTTP & HTTPS (Layer 7)
- Health checks are TCP or HTTP based
- Fixed hostname: XXX.region.elb.amazonaws.com
- Application Load Balancer (v2) - ALB: HTTP, HTTPS, WebSocket
- Layer 7 (HTTP)
- Load balancing to multiple HTTP applications across machines (target groups)
- Load balancing to multiple applications on the same machine (ex: containers)
- Support for HTTP/2 and WebSocket
- Support redirects (from HTTP to HTTPS for example)
- Routing tables to different target groups:
- Routing based on path in URL
- Routing based on hostname in URL
- Routing based on Query String, Headers
- ALB are a great fit for micro services & container-based application (example: Docker & Amazon ECS)
- Has a port mapping feature to redirect to a dynamic port in ECS
- In comparison, we'd need multiple Classic Load Balancer per application
- Target Groups:
- EC2 Instances (can be managed by an Auto Scaling Group) - HTTP
- ECS task (managed by ECS itself) - HTTP
- Lambda functions - HTTP request is translated into a JSON event
- IP Addresses - must be private IPs
- ALB can route to a multiple target groups
- Health checks are at the target group level
- Good to Know:
- Fixed hostname (XXX.region.elb.amazonaws.com)
- The application servers don't see the IP of the client directly
- The true IP of the client is inserted in the header X-Forwarded-For
- We can also get Port (X-Forwarded-Port) and proto (X-Forwarded-Proto)
- Network Load Balancer (v2) - NLB: TCP, TLS (secure TCP), UPD
- Gateway Load Balancer - GWLB: Operates at layer 3 (Network layer) - IP Protocol
- Recommended to use newer gens
- Some can be setup as internal or external ELBs
Note
0.0(0)
Explore Top NotesNoteStudied by 10 peopleNoteStudied by 1348 peopleNoteStudied by 131 peopleNoteStudied by 6 peopleNoteStudied by 3 peopleNoteStudied by 38 people
Chapter 16 - Conclusions
NoteStudied by 10 peopleAP US History Unit 1 Content Outline
NoteStudied by 1348 peopleallemand
NoteStudied by 131 peopleChapter 14: Injury and Illness
NoteStudied by 6 peopleV. Scientific Revolution (Chapter 16)
NoteStudied by 3 peopleINTRODUCTION: MATTER, ENERGY, AND MEASUREMENT
NoteStudied by 38 people