Elas%c Load Balancing, Amazon CloudWatch, and Auto Scaling Sco) Linder

Transcription

1 Elas%c Load Balancing, Amazon, and Auto Scaling Sco) Linder Overview Elas4c Load Balancing Features/Restric4ons Connec4on Types Listeners Configura4on Op4ons Auto Scaling Launch Configura4ons Scaling Types Scaling Policies Elas%c Load Balancing () Horizontal scaling Distribute requests across mul4ple instances Managed (i.e. hosted as a service) solu4on Has an associated cost 1

2 Features/Restric%ons Supported Protocols HTTP HTTPS SSL (Generic, encrypted) TCP (Generic, unencrypted) Load balancing is per-region Can span mul4ple Availability Zones Can be public (Internet-facing) or private (Internal) Public s provide a single DNS CNAME entry point Region Zones Features/Restric%ons Cont. Dynamic rou4ng based on health checks Stops rou4ng to unhealthy instances Automa4cally scales based on metrics Also integrates with Auto Scaling Supports SSL termina4on Region Zones Connec%on Types Internet-facing Connects the public-facing end of the to the Internet Internal Connects the public-facing end of the to other subnets in your VPC HTTPS Uses SSL termina4on (SSL Offload) with a cer4ficate associated with the Internet HTTPS HTTP SSL Cer4ficate 2

3 HTTPS With SSL termina4on, the must manage the SSL Cer5ficate If hos4ng mul5ple sites on the same : Must provide exactly one cer4ficate This cer4ficate must contain any extra domain names as Subject Alterna5ve Names (SAN) Mul4ple cer4ficates via Server Name Iden5fica5on (SNI) are not supported SAN: SAN: example.net SAN: example.org example.net example.org Listeners must have at least one Can have many Consist of: Front-end Protocol Internet Front-end Port Back-end Protocol Back-end Port Each client requests results in two connec4ons One from client to One from to an instance Configura%on Op%ons Idle Connec4on Timeout Each connec4on 4mes out a_er no data is sent for specified 4me Cross-Zone load balancing Ensures requests distributed evenly, even across Availability Zones S4ll good to create equal number of instances in each zone Connec4on Draining Wait for a specified 4meout before termina4ng exis4ng connec4ons to an unhealthy instance Proxy Protocol Insert request informa4on 3

4 Configura%on Op%ons Cont. S4cky Sessions Also known as Session Affinity Prefer to route mul4ple requests from same client to the same instance Can reuse applica4on cookies, or generate a cookie Health Checks Can be one of: Ping Connec4on A)empt Page Load Time between checks, required failed checks configurable Amazon Monitor (almost) any AWS service Inject custom metrics via PUT request Use metrics to: Aggregate logs Create alarms Execute arbitrary code metrics Only hypervisor-visible (e.g. CPU Usage) Other (e.g. memory/disk usage) must be PUT Amazon SNS Add Alert message to queue CPU U4liza4on > 80% For 2 minutes Monitoring Types Basic This level is included for no cost Metrics are sampled every five (5) minutes Limited metrics Detailed Available for a cost Must be enabled (Basic is default) Metrics are sampled every one (1) minute Metrics can be aggregated 4

5 Log Aggrega%on can aggregate instance/ applica4on logs to S3/Glacier Can monitor error rates Logs Agent Can be installed on instances to provide easy interface to send applica4on logs to S3 Aggregate Applica4on Logs Logs Agent Auto Scaling Automa4cally provision and terminate instances to match need Minimize cost while allowing for changing workload Based around configuring an Auto Scaling group comprising: Name Minimum instance count Maximum instance count Desired instance count (op4onal; defaults to Minimum) Elas4c Load Balancer (op4onal) Addi4onally need a Launch Configura5on and (op4onal) Scaling Policy Launch Configura%ons Template used by Auto Scaling to create new instances Cannot require manual interven4on Components: Name Amazon Machine Image (AMI) Instance type Security Group(s) Key pair 5

6 Scaling Types Maintain Current Levels Simply replace failed instances to maintain desired capacity Manual Scaling Upda4ng minimum/desired/maximum capacity by hand Scheduled Scaling Vary capacity with 4me (e.g. for Black Friday traffic spikes) Dynamic Scaling Most flexible Can respond to metrics like network bandwidth or CPU usage Based on programs called Scaling Policies Scaling Policies Respond to metrics CPU Usage Bandwidth Usage Reaching a threshold for a sustained period When CPU usage exceeds 80% for 300 seconds By scaling in or out by a fixed amount or a percentage Double compute capacity Recommended: Scale out fast, scale in slow (have a cooldown period) Instances are billed for at least one hour once started + + Auto Scaling Why are these all in one chapter? They work best together. Alarms (ScaleIn/ScaleOut) Region Auto Scaling Group Metrics Zones 6