如何创建警报以检测DynamoDb限制已达到一定百分比，然后将其增加 [英] How do I create an Alarm to detect DynamoDb limits have reached a certain percent and then increase it

问题描述

我正在编写一个网络应用程序，该应用程序在一天之中的流量一直在稳定增长。我想创建一个警报，该警报可以检测我的读/写限制是否已达到某个百分比（例如80％），然后增加该限制。然后，我将在午夜再次将其降低。

I'm writing a web application that has steadily increasing traffic through the day. I'd like to create an Alarm that can detect if my read / write limits have reached a certain percentage (like 80%), and then increase that limit. I will then decrease it again at midnight.

我尝试创建一个警报-平均似乎有点用处，始终为1.0。 Sum更有用，所以我认为我应该使用它。我还假设我应该在指标名称上使用消耗的写入/读取容量。

I've tried creating an Alarm - "Average" seems a bit useless and is always 1.0. "Sum" is more useful so I assume i should use this. I also assume i should use Consumed Write/Read Capacity at the metric name.

问题：

• 总和似乎将绝对值 Count用作其限制。如果我的DynamoDB设置为100次写入，并且我设置了80％的警报，它将检查我的写入是否超过0.8，而不是80。

• Sum seems to use an absolute value of "Count" for its limits. If my DynamoDB is set to 100 writes, and i setup an alarm for 80%, it checks if my writes exceed 0.8, not 80.

我已经设置一个电子邮件主题，但这是不正确的-我假设我需要创建一个可以调用该主题的函数/控制器。我将如何设置它，如果您有2个Amazon VM，两者都会被调用还是只有一个？还是这是一条错误的路线，并且可以对事件采取一种标准措施以增加DynamoDB限制而无需编写任何代码。 （我对SNS知识的缺乏可能在这里显示）

I've setup an email topic, but this is not correct - I assume I need to create a function/controller which a topic can call. How would i set this up and if you have 2 Amazon VM's, would both get called or just one? Or is this the wrong route and there is a standard action one can take on events to increase DynamoDB limits without coding anything. (my lack of SNS knowledge is probably showing here)

推荐答案

亚马逊的向导创建了一个表，它建议在 80％阈值处创建警报并将其链接到 SNS主题。

When running Amazon's wizard to create a table, it suggests to create an alarm at 80% threshold and to link it to an SNS topic.

在引擎盖下，对于R / W容量为1，这会在以下情况上产生警报

Under the hood, for R/W capacity of 1, this creates an alarm on

• ConsumedReadCapacityUnits> = 240 for 60分钟


• ConsumedWriteCapacityUnits> = 240，持续60分钟

240 = 0.8 * 1 * 60 * 5 ，即容量（1）* seconds_in_5_minutes（300）*阈值（0.8）。警报时间为60分钟。您可以缩短至5分钟，但这可能会增加误报的次数。

240 = 0.8*1*60*5 that is to say, capacity(1) * seconds_in_5_minutes(300) * threshold(0.8). 60 minutes is the alarm period. You can shorten down to 5 min but this might increase the number of false positive.

换句话说，每当消耗容量单位为5分钟的范围超过24阈值至少1小时。

In other words, the alarm is triggered every time the sum of the consumed capacity units on ranges of 5 min exceeds the 24 treshold for at least 1 hour.

注意：5分钟对应于采样时间。

note: 5 min corresponds to the sampling period.

在 SNS 中控制台，您可以在主题中添加 订户。它们可以是电子邮件，HTTP（S）回调... ...这使您可以联系多个人/机器。

In the SNS console, you can add 'subscribers' to a topic. They can be e-mails, HTTP(S) callbacks, ... This allow you to contact multiple human/machines.

每次触发扩展逻辑时，您将需要使用API​​使用此公式自动更新警报。

Every time your scaling logic is triggered, you will need to use the API to automatically update the alarms using this formula.

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