Скачать или смотреть Resolving AWS AutoScaling Schedule Timezone Issues with Terraform

Learn how to handle timezone discrepancies in AWS AutoScaling schedules using Terraform. This guide provides step-by-step solutions to common issues with scheduling across multiple regions.
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Handling AWS AutoScaling via Terraform: A Guide to Timezone Issues

When managing your AWS infrastructure, especially when it spans multiple regions, you may face challenges, particularly with time-based scheduling tasks. In this post, we’ll dive into one common problem: configuring the AWS AutoScaling schedule using Terraform in regions that operate in different timezones.

The Problem: Timezones in AWS AutoScaling

As you might know, AWS’s aws_autoscaling_schedule resource defaults to UTC time, which can lead to complications if your goal is to perform actions, such as scaling your Auto Scaling Groups (ASGs), based on the local time of each region.

Example Scenario

Imagine you have several regions in your AWS cloud infrastructure, and you want to schedule a scale down action at 6 PM local time for each respective region. When you try to do this using the standard recurrence format in Terraform, you quickly realize that there’s no built-in way to specify the timezone within the recurrence attribute. Here's an excerpt of what your Terraform code might look like:

[[See Video to Reveal this Text or Code Snippet]]

The above piece of code tries to set a scaling down action at 6 PM every Friday, but it does so according to UTC time, which may not align with the local times of your target regions.

The Solution: Adjusting the Recurrence with Variables

To address this issue, you need to implement a slight change to how the recurrence is defined within your configuration. Instead of attempting to directly manipulate the recurrence variable, you should leverage Terraform's interpolation syntax. Here’s how to do it properly:

Correcting Your Code

Instead of writing:

[[See Video to Reveal this Text or Code Snippet]]

You should leverage Terraform's interpolation syntax like this:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Changes

Interpolation Syntax: The ${} syntax tells Terraform to substitute the value of var.temp_var directly into the string. This is crucial:

If var.temp_var is set to 18 for a region where local time at 6 PM should trigger the scaling down, the recurrence string will evaluate properly as 0 18 * * 5.

Implementation Steps

Adjust your variables.tf or region-specific variables file to include the correct target hour for scaling down tailored to each region.

Ensure that var.temp_var contains the local hour (in 24-hour format) for scaling down.

Test your changes using terraform plan and terraform apply to confirm that the scheduling behaves as expected.

Conclusion

Correctly managing AWS AutoScaling schedules across multiple timezones can be tricky. However, with the right adjustments to your Terraform code, you can achieve desired behaviors that align with local times across various regions.

By following the guidance in this post, you should be able to incorporate timezone-aware scaling actions into your AWS managing script effectively. If you have any further questions or need additional support, feel free to reach out!