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ALB 支援 Slow Start 了

這個功能在 ELB Classic 年代時有跟 AWS 提過,到 ALB 支援了 (總算...):「Application Load Balancer Announces Slow Start Support for its Load Balancing Algorithm」。

Application Load Balancers now support a slow start mode that allows you to add new targets without overwhelming them with a flood of requests. With the slow start mode, targets warm up before accepting their fair share of requests based on a ramp-up period that you specify.

然後時間可以設定,從 30 秒到 15 分鐘:

Slow start mode can be enabled by target group and can be configured for a duration of 30 seconds to 15 minutes. The load balancer linearly increases the number of requests sent to a new target in a target group up to its fair share during the slow start ramp-up window.

就之前的經驗來說,這在跑 PHP 的時候會很需要這個功能 (之前是在 F5 的設備上設定)。其他的語言因為性質不太一樣,可能不會這麼吃這個功能。

主要是因為 PHP 是在 request 進來時 compile 並且 cache。所以在機器剛起來時,儘量將 CPU 留給 opcache,把常用的頁面 compile 完並且放進 cache,而不是讓大量的連線灌進來,這樣對使用體驗不會太好... (要避免 CPU 吃滿 100% 很久,造成每個連線都很慢才跑完)

AWS 推出 Slow Start 後對 auto scaling 時的順暢度會好不少...

Amazon ECS 的 Service Discovery

AWS 宣佈了 Amazon ECS 也支援 Route 53 提供的 Service Discovery 了:「Introducing Service Discovery for Amazon ECS」。

也就是說現在都整合好了... 比較一下先前需要自己包裝起來套用的方式會少不少功夫:

Previously, to ensure that services were able to discover and connect with each other, you had to configure and run your own service discovery system or connect every service to a load balancer. Now, you can enable service discovery for your containerized services with a simple selection in the ECS console, AWS CLI, or using the ECS API.

AWS 在 2016 年的時候有寫一篇「Service Discovery for Amazon ECS Using DNS」在講怎麼透過事件的觸發配合 AWS Lambda 把服務掛上去或是移除掉:

Recently, we proposed a reference architecture for ELB-based service discovery that uses Amazon CloudWatch Events and AWS Lambda to register the service in Amazon Route 53 and uses Elastic Load Balancing functionality to perform health checks and manage request routing. An ELB-based service discovery solution works well for most services, but some services do not need a load balancer.

現在看起來都可以改用 Auto Naming API 了...

Amazon Route 53 的 Auto Naming API 可以指到 CNAME 位置了

Amazon Route 53 的 Auto Naming API 可以拿來跑 Service Discovery (參考先前的「用 Amazon Route 53 做 Service Discovery」這篇),當時是 A/AAAA/SRV record,現在則可以註冊 CNAME 了:「Amazon Route 53 Auto Naming Announces Support for CNAME Record Type and Alias to ELB」。

最直接的影響就是 ELB 的部份了,透過 ELB 處理前端的話,覆載平衡以及數量限制的問題就會減輕很多 (之前是靠 Round-robin DNS 打散,而且限制一次最多回應五個 record):

Beginning today, you can use the Amazon Route 53 Auto Naming APIs to create CNAME records when you register instances of your microservices, and your microservices can discover the CNAMEs by querying DNS for the service name. Additionally, you can use the Amazon Route 53 Auto Naming APIs to create Route 53 alias records that route traffic to Amazon Elastic Load Balancers (ELBs).

Amazon Lightsail 推出 Block Storage 與 Load Balancer

Amazon Lightsail 推出了 Block Storage (11/14) 與 Load Balancer (11/29):「Introducing additional block storage for Amazon Lightsail」、「Amazon Lightsail adds load balancers with integrated certificate management」。

兩個是不同時間點發表的,當時懶的寫所以這次一起寫...

Block Storage 有不少 VPS 都有提供了,像是 Linode 的「Linode Block Storage (Fremont beta)」(雖然還在 beta)、DigitalOcean 的「Storage on DigitalOcean | Highly available Block Storage」以及 Vultr 的「High Performance and Cheap Block Storage - Vultr.com」。

AWS 算是很早就有這個服務 (Amazon EBS),這邊應該只是把系統整合進來...

另外一個是這幾天推出的 Load Balancer,目前應該只有 Linode 的「Ensure High-Availability with NodeBalancers - Linode」比較知名。AWS 上的 ELB 有不少選擇可以用 (ELB Classic、ALB 以及 NLB),不過公告裡沒特別提到... 比較特別的是提供免費的 SSL Certificate 吧?這在其他家主要得靠 Let's Encrypt 來做,在 AWS 上應該是整合了 ACM

AWS 推出將 Classic Load Balancer 轉換成 Application Load Balancer 或 Network Load Balancer 的功能

AWS 應該是希望大家趕快把能換的 ELB 都換成新的 ALB 與 NLB,所以推出這個功能:「New One-step Migration Wizard to Migrate a Classic Load Balancer」。

Today, AWS announced the ability to migrate from a Classic Load Balancer to an Application Load Balancer or a Network Load Balancer in one step using a console-based migration wizard.

不過 ELB 有一些功能是目前 ALB 與 NLB 沒有的,像是一般性的 SSL offload (而非 HTTPS offload),以及舊客戶會有的 EC2-Classic:

不知道這兩個問題之後會推出什麼樣的方案解決...

AWS PrivateLink

AWS 計畫把先前設計的 VPC Endpoint 都併到 AWS PrivateLink 裡,統一管理:「New – AWS PrivateLink for AWS Services: Kinesis, Service Catalog, EC2 Systems Manager, Amazon EC2 APIs, and ELB APIs in your VPC」。

Today we are announcing AWS PrivateLink, the newest generation of VPC Endpoints which is designed for customers to access AWS services in a highly available and scalable manner, while keeping all the traffic within the AWS network. Kinesis, Service Catalog, Amazon EC2, EC2 Systems Manager (SSM), and Elastic Load Balancing (ELB) APIs are now available to use inside your VPC, with support for more services coming soon such as Key Management Service (KMS) and Amazon Cloudwatch.

這樣就不用弄 proxy server 然後在上面管一堆 policy 了... (先不講自己搞 HA 的麻煩事,光是有些程式還得 patch 才能支援 proxy 就會想翻桌了 XD)

ALB 支援 SNI

AWS 宣佈 ALB 支援 SNI 了:「Application Load Balancers Now Support Multiple TLS Certificates With Smart Selection Using SNI」。

不過這篇比較有趣的是,他範例用的是 VimIsBetterThanEmacs.comVimIsTheBest.com 這兩個網域名稱 XDDD:

I’ll use a few example websites like VimIsBetterThanEmacs.com and VimIsTheBest.com. I’ve purchased and hosted these domains on Amazon Route 53, and provisioned two separate certificates for them in AWS Certificate Manager (ACM). If I want to securely serve both of these sites through a single ALB, I can quickly add both certificates in the console.

AWS NLB 也可以指定 IP address 當後端了

月初的時候 AWS ALB 支援 IP address 當後端 (AWS ALB 可以設定 IP address 當作後端伺服器了),然後推出 AWS NLB (AWS 推出新的 Load Balancer:NLB (Network Load Balancer)),然後這個功能也被做到 NLB 上了:「Elastic Load Balancing: Network Load Balancer now supports load balancing to IP addresses as targets for AWS and on-premises resources」。

就如同說明的,這樣可以透過 VPN 架構 (無論是 AWS Direct Connect 或是一般的 IPsec VPN) 共用機房與雲端上的資源:

We are pleased to announce that Network Load Balancers can now distribute traffic to AWS resources using their IP addresses as targets in addition to the instance IDs. You can now also load balance to resources in on-premises locations reachable over AWS Direct Connect and resources in EC2-Classic. Load balancing across AWS and on-premises resources using the same load balancer makes it easy for you to migrate-to-cloud, burst-to-cloud, or failover-to-cloud.

除了中國區以外的 region 都可以用這個功能了:

Load balancing using IP addresses is available today for existing and new Network Load Balancers in all public AWS regions except the China (Beijing) region. You can get started using the AWS Management Console, AWS Command Line Interface (CLI), or AWS SDK.

AWS 推出新的 Load Balancer:NLB (Network Load Balancer)

從一開始推出的 ELB (Elastic Load Balancer),到 ALB (Application),現在則推出了 NLB (Network):「New Network Load Balancer – Effortless Scaling to Millions of Requests per Second」。

有這些特性:

  1. Static IP Addresses
  2. Zonality
  3. Source Address Preservation
  4. Long-running Connections
  5. Failover

雖然不能確定 AWS 用的技術是什麼,但這裡面有好幾個很明顯就是 DSR (Direct Server Return) 架構的特性 (包括了限制與優點)。

另外也因為不用處理 L7 的內容,效能比起 ELB/ALB 好很多,夠大的用量下,價錢也低不少。對於不少非 HTTP/HTTPS 的應用應該很好用,就算是 HTTP/HTTPS,單純一點的應用應該也不錯...

AWS ALB 可以設定 IP address 當作後端伺服器了

AWS ALB 推出直接設定 IP address 當作後端伺服器的功能:「New – Application Load Balancing via IP Address to AWS & On-Premises Resources」。

ip – Targets are registered as IP addresses. You can use any IPv4 address from the load balancer’s VPC CIDR for targets within load balancer’s VPC and any IPv4 address from the RFC 1918 ranges (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16) or the RFC 6598 range (100.64.0.0/10) for targets located outside the load balancer’s VPC (this includes Peered VPC, EC2-Classic, and on-premises targets reachable over Direct Connect or VPN).

這樣就能拿 ALB 當 load balancer 把部份內容接到自己機房內的伺服器群了,一種隨便串的概念... (可以透過 AWS Direct Connect 或是 VPN 直接串,所以對外的部份就直接是 AWS 端,對內要怎麼接就隨便接...)

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