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I am building solution based on EC2 using AutoScaling.
I have created the solution where instance will get detached from AutoScaling group before they are stopped and they will be added back to AutoScaling group when in use.
Now what if the instance that I have deteched from AutoScaling has terminated, now I am left with nothing to attach to AutoScaling ( that particular instance id does not exist anymore).
How to handle this , if instance has terminated then at time of attachment AutoScaling should know that Instance does not exist anymore and create a new instance.
From here i am planning to create a event bridge which will take Instance-Id of new instance and update it SSM.
I think you might want to use standby instead of detaching/attaching. Any time you have an instance exit standby, the desired will get incremented by 1. No healthchecks are happening on the instance while its in standby, so if the instance got terminated while in standby the ASG wouldn't know about it until you remove the instance from standby.
Since the desired has already been increased at that point, a new instance would be launched to replace the old one as part of a healthcheck replacement
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I have created ec2 instance and it's part of the auto scaling group and i want to stop this instance so i can save money while this server being not used.Whenever i want to use this server that time i can start the instance.
AutoScaling Group is able to take care of this process for you.
You can change the size of the group manually, or you could schedule custom configurations to scale-up or scale-down as per your needs.
This is all supported through AWS APIs, so you can do this through AWS Console or automating the configuration.
Instances in ASG can't be stopped. If you want to stop one instance you have to detach it from ASG. When you are ready to start it, you can attach it again.
But really, you should reconsider how you use ASG. Detaching and re-attaching instances from ASG is meant for mostly troubleshooting purposes, not something you do regulatory just to save cost. Its better to set minimum and desired capacity of ASG to 0 if you don't want any instance in it.
I have an ASG with desired/min/max of 1/1/5 instances (I want ASG just for rolling deploys and zone failover). When I start the Instance refresh with MinHealthyPercentage=100,InstanceWarmup=180, the process starts by deregistration (the instance goes to draining mode almost immediately on my ALB, instead waiting the 180 Warmup seconds until the new instance is healthy) and the application becomes unavailable for a while.
Note that this is not specific just to my case with one instance. If I had two instances, the process also starts by deregistering one of the instances and that does not fulfill the 100% MinHealthy constraint either (the app will stay available, though)!
Is there any other configuration option I should tune to get the rolling update create and warm up the new instance first?
Currently instance refresh always terminates before launching, and it uses the minHealthyPercent to determine batch size and when it can move on to the next batch.
It takes a set of instances out of service, terminates them, and launches a set of instances with the new desired configuration. Then, it waits until the instances pass your health checks and complete warmup before it moves on to replacing other instances.
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Setting the minimum healthy percentage to 100 percent limits the rate of replacement to one instance at a time. In contrast, setting it to 0 percent causes all instances to be replaced at the same time.
https://docs.aws.amazon.com/autoscaling/ec2/userguide/asg-instance-refresh.html
If you are running the 1 instance and using the Launch template with the Autoscaling it would be hard to rolling update the EC2 instance.
i am coming from the above scenario and hitting up on this immature feature of AWS.
it's mentioned in the limitation of instance refresh, it will scale down the instance and will recreate the new one instead of creating the first new one instance.
Instances terminated before launch: When there is only one instance in
the Auto Scaling group, starting an instance refresh can result in an
outage. This is because Amazon EC2 Auto Scaling terminates an instance
and then launches a new instance.
Ref : https://docs.aws.amazon.com/autoscaling/ec2/userguide/asg-instance-refresh.html
i tried work around of scaling up the auto-scaling group desired size to 2, it will create a new instance with the latest AMI in the launch template.
Now you have two instances running the old version & latest version, you will be good to set the desired capacity now back to 1 in the auto-scaling group.
Auto-scaling desired capacity to 1 will delete the older instance and keep the latest instance with the latest AMI.
Command to update desired capacity to 2
- aws autoscaling update-auto-scaling-group --auto-scaling-group-name $ASG_GROUP --desired-capacity 2
Command to update desired capacity to 1
- aws autoscaling update-auto-scaling-group --auto-scaling-group-name $ASG_GROUP --desired-capacity 1
Instead of using the instance-refresh this worked well for me.
This does not seem to be the case anymore. An instance refresh creates now a fresh instance and terminates the old one after health checks are successful. AWS Support mentioned this behavior was not changed since 2020.
it seems that I have a technical issue regarding terminating the EC2 instance.
When I terminate it, a new instance is being created with the same name.
I terminate an EC2 instance. After a refresh, another instance was running so I started to terminate it.
After one another refresh of the page, a new instance started to run.
Do you maybe have any tips regarding this?
This instance seems to be a part of the autoscaling group which is continuously trying to meet the minimum capacity requirements. Delete that Autoscaling group first and then stop the instance or update Min capacity in autoscaling group to 0 it will be automatically terminated.
I have foreseen a problem that could happen with my application but I am unsure if it is possible to solve, and perhaps the architecture needs to be redesigned.
I am using an AutoScalingGroup (ASG) on AWS to create EC2 instances that host game servers that players can join. At the moment, the ASG is scaled manually via a matchmaking API which changes the desired capacity based on its needs. The problem occurs when a game server is finished.
When a game finishes, it signals to the matchmaker that it is finished and needs terminating, and the matchmaker will then scale down the ASG accordingly, however, it doesn't seem to know exactly which instance to remove, and it won't necessarily be the one that needs terminating.
I can terminate the instance, but then as the ASG desired capacity is never changed when the instance is terminated, another server is created.
Is there a way I can scale down the ASG, as well as specifying which servers to remove from the group?
In a nutshell, the default termination policy during scale in is designed to remove instances that use the oldest launch configuration.
Currently, Amazon EC2 Auto Scaling supports the following termination policie:
OldestInstance Terminate the oldest instance in the group. This option is useful when you're upgrading the instances in the Auto Scaling group to a new EC2 instance type. You can gradually replace instances of the old type with instances of the new type.
NewestInstance Terminate the newest instance in the group. This policy is useful when you're testing a new launch configuration but don't want to keep it in production.
OldestLaunchConfiguration Terminate instances that have the oldest launch configuration. This policy is useful when you're updating a group and phasing out the instances from a previous configuration.
ClosestToNextInstanceHour Terminate instances that are closest to the next billing hour. This policy helps you maximize the use of your instances and manage your Amazon EC2 usage costs.
Default Terminate instances according to the default termination policy. This policy is useful when you have more than one scaling policy for the group.
Instance protection
One of the possible solutions could be to use Instance protection. The auto-scaling provides an instance protection to control whether instance can be terminated when scaling-in.
Therefore, enable the instance protection for ASG to protect instances from scaling-in by default. Once you are done with you server, decrease a value of desired number of instances, remove instance protection from particular instance (either using CLI or SDK; note that this protection remains enabled for the rest of instances) and auto-scaling will terminate that exact instance.
For more information about instance protection, see Instance Protection
The oldest server is removed. If you want to scale down a specific server, you will have to kill that server before changing desired capacity.
You can create new Launch Configuration (updating AMI or whatever) and attach this with an existing Autoscaling Group. Per AWS Docs: After you change the launch configuration for an Auto Scaling group, any new instances are launched using the new configuration options, but existing instances are not affected.
How do you force this? Meaning relaunch all new instances now (with the new AMI). Do I have to delete the existing Autoscaling Group and create a new Autoscaling Group (with new Config)? Or I simple delete existing instances (one by one manually) and then ASG relaunch with new AMI. Any best practices/gotchas?
CloudFormation has the RollingUpdate flag (not sure of this outside of CF)
Thanks
AWS has some OOTB solutions for this, CloudFormation (like you say), Elastic Beanstalk (built on top of CF), and CodeDeploy blue-green deployments (I've not tried this).
Personally for our SQS polling ASG, we do a "cold deploy" i.e. only "deploy" when there are no messages to process (and hence, due a scaling policy, no instances). It's been really effective.
A deploy can be done safely whilst there are messages, provided that you set scale-in-protection on the instance during message processing (and remove it and wait briefly before polling):
set desired-capacity to 0
wait a bit (for there to be no instances running)
set desired-capacity back to N.
Note: you can do this all in the console.
You can code a solution yourself that does this... but I probably wouldn't.
Be careful:
simple delete existing instances (one by one manually)
Whether you can do this, or depends on whether the instances are still handling requests/processing (usually you can't simply terminate an instance without dropping service).
I recommend Elastic Beanstalk which gives a rolling update feature for free and is very easy to get started. I've not tried the CodeDeploy blue-green but it looks interesting. If you want more advanced behavior (or are already using it) look into Cloud Formation... do not code your own solution for rolling deployments: just use CloudFormation.
if your issue is with "in flight" requests simply enable connection draining or increase de-registration delay of the ELB or "target groups" attached with the ASG. You can set a value up to one hour.
When you enable connection draining, you can specify a maximum time for the load balancer to keep connections alive before reporting the instance as de-registered. The maximum timeout value can be set between 1 and 3,600 seconds (the default is 300 seconds). When the maximum time limit is reached, the load balancer forcibly closes connections to the de-registering instance.
Then you can detached old instances.
If you detach an instance from an Auto Scaling group that has an attached load balancer, the instance is deregistered from the load balancer. If you detach an instance from an Auto Scaling group that has an attached target group, the instance is deregistered from the target group. If connection draining is enabled for your load balancer, Auto Scaling waits for in-flight requests to complete.
If you don't want to do any manual scaling I guess the best approach is to changing the termination policy to OldestInstance and leave the ASG as it is. When the scale-in activity happens ASG will automatically terminate the old instances.(in your case old launch config instances)
OldestInstance. Auto Scaling terminates the oldest instance in the group. This option is useful when you're upgrading the instances in the Auto Scaling group to a new EC2 instance type. You can gradually replace instances of the old type with instances of the new type.