Pros, Cons, and traps of EC2 Instance Start and Stop Schedules with AWS Lambda
Tags: ec2, lambda, automation, devops
Published: 2023-10-31 12:47:50

Managing EC2 instances efficiently through automated start and stop schedules is a best practice for optimizing cloud resources. 
By using AWS Lambda functions and tags on EC2 instances, you can automate the process and save on costs. 
In this article, I will try to highlight some of the advantages, disadvantages, and potential traps of implementing EC2 instance schedules.

Are you tired of reading? You can listen on YouTube:


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1) Pros of EC2 Instance Scheduling:
Of course, the solution has many advantages, and when you take a closer look at it, you can also see the less obvious ones. Below are some of them:

- Cost Savings:
One of the most significant benefits of EC2 scheduling is cost reduction. By shutting down instances during non-business hours or when they're not needed, you can significantly reduce your AWS bill.

- Time Savings:
If you can do something automatically, you probably should do it. It's best to set something up once and forget about it. Don't waste time repeating the same activities. Of course, good documentation is also important here ;)

- Eco-Friendly:
Scheduling instances to run only when necessary is environmentally friendly. It reduces power consumption and contributes to a greener cloud infrastructure.

- Easy Maintenance:
Scheduled stops make maintenance and updates easier because you can be sure your instances won't be in use during patching or other maintenance activities. So you can restart them and do whatever you need with them because you know that no one is using them at that time.

- Errors reduction:
Reducing errors coming from human mistakes. When you do something manually for a large number of machines, better don't make a mistake and accidentally don't turn off production ;)


2) Cons and Challenges of EC2 Scheduling:

- Complex Setup:
Configuring the necessary components, such as CloudWatch Events rules and Lambda functions, can be complex, especially when dealing with multiple, projects, teams, regions and schedules.

- Pitfalls of Time Zones:
Managing schedules that involve multiple time zones or regions can be challenging. It's crucial to consider time zone differences and daylight saving time when creating your schedules.

- Resource Dependency:
Instances that rely on other services may encounter issues when stopped. For example, databases or application servers may require extra considerations and additional commands when being stopped and started.

- Monitoring and Alerting:
Ensuring that schedules work as expected and dealing with any failures can be a continuous task. Proper monitoring and alerting are essential to maintain the system. It's good to know whether the running instance is working properly.


3) Potential Traps to Avoid:

- Forgetting Critical Instances:
Failing to tag all relevant instances or forgetting to include specific instances in your schedules can lead to unexpected downtime or increased costs.

- Complex Schedules:
Overly complex schedules with numerous rules and exceptions can become difficult to manage and troubleshoot.

- Human Error:
As I mentioned earlier misconfigurations in your Lambda functions or CloudWatch Events rules can have unintended consequences, so it's essential to thoroughly test your setup.

- Complicated environments
Sometimes it is important in what order you turn the services off and on. Some services should already be running before others, otherwise they will return errors. 
Some services should finish writing data before closing. Typically you shouldn't shut down EC2 machines while services are still writing data. 
It's a good idea to wait until the services finish their activities and close themselves properly and not force them to do this.


Conclusion:
Automating EC2 instance start and stop schedules with AWS Lambda functions offers significant benefits, primarily cost savings and resource optimization. However, there are complexities and potential pitfalls to navigate. 
Ensuring a smooth and reliable scheduling system requires careful planning, regular monitoring, and testing. By addressing the challenges and pitfalls, you can maximize the advantages of EC2 scheduling and make the most of your AWS resources while maintaining cost efficiency.

If you want to see one of the ways how to turn off and on ec2 machines containing a specific TAG using the lambda function and cludwatch event, I recommend watching my video tutorial: https://youtu.be/-GzWgAdK22E?feature=shared

{% embed https://youtu.be/-GzWgAdK22E %}

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