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.
Related
I am trying to figure out when and how AWS deregisters an EC2 from an auto-scaling group during scale-in. I am especially worried about a case when an EC2 which is about to be terminated will receive an incoming request shortly before being terminated. This would naturally cause processing of the requst to fail. The desired behavior would be for AWS to deregister the about-to-be-terminated instance from the group some configurable time before actually terminating it. I have found no documentation about this specific issue. Am I missing something?
There's no configuration that guarantees that a specific time elapses between deregistering an instance from the group and terminating it.
You can use Elastic Load Balancer health checks to remove instances that are not responding from the load balancer endpoint before they are terminated.
From AWS Documentation https://docs.aws.amazon.com/autoscaling/ec2/userguide/ec2-auto-scaling-termination-policies.html
Default termination policy
The default termination policy applies multiple termination criteria before selecting an instance to terminate. When Amazon EC2 Auto Scaling terminates instances, it first determines which Availability Zones have the most instances, and it finds at least one instance that is not protected from scale in. Within the selected Availability Zone, the following default termination policy behaviour applies:
Determine whether any of the instances eligible for termination use the oldest launch template or launch configuration:
[For Auto Scaling groups that use a launch template]
Determine whether any of the instances use the oldest launch template, unless there are instances that use a launch configuration. Amazon EC2 Auto Scaling terminates instances that use a launch configuration before it terminates instances that use a launch template.
[For Auto Scaling groups that use a launch configuration]
Determine whether any of the instances use the oldest launch configuration.
After applying the preceding criteria, if there are multiple unprotected instances to terminate, determine which instances are closest to the next billing hour. If there are multiple unprotected instances closest to the next billing hour, terminate one of these instances at random.
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 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.
I configured for my AWS account the new AWS instance scheduler https://aws.amazon.com/answers/infrastructure-management/instance-scheduler/
The problem seems that, tagging ec2-instances through a scaling group the ec2-instances are correctly stopped, but since my scaling group has Min number set to 2 AWS scaling group restarts them anyway.
I would not like to set Min number to 0, just because is useful during application redeploy.
How to make the 2 services work fine?
When you stop your EC2 instances that are controlled by Auto Scaling, then Auto Scaling will see them as "unhealthy" and it will proceed to terminate and replace them.
You have 2 options.
Option 1: Pause Auto Scaling processing while your EC2 instances are stopped. By doing this, Auto Scaling won't care that your EC2 instances are stopped and won't terminate them. Just remember to resume processing after you restart your EC2 instances.
However, AWS Instance Scheduler will not manage this for you, so you'll need to find another way to schedule your EC2 instances to stop & restart.
Option 2: Scale your Auto Scaling group to 0 and back to 2. This will result in terminating your EC2 instances (when you don't need them) and re-creating them (when you want them). This will only work if your EC2 instances are ephemeral.
Again, AWS Instance Scheduler will not manage this for you. Auto Scaling scheduled actions may be able to help you with this.
Another option is to use asg standby feature before and after the aws instance scheduler. This will also let you work on the same Ami before the shutdown.
So high level solution is below:
Define ec2 instance schedule using aws instance scheduler
Define lambda that fetch the shutdown schedule and put the ec2 in standby mode before the planned shutdown.
Define lambda that fetch the startup schedule and put the ec2 instance out of standby after the ec2 planned restart.
I'm looking to see if I can create an instance and deploy applications to athis instance dynamically via the API. I only want these instances to be created when my application needs them, or I request for them to be created.
I have two applications that I need to deploy to each created instance which require some set up and installation of dependencies prior to their launch. When I am finished with this application, I want to terminate the instance.
Am I able to do this? If so, could someone please point me to the right section of the documentation. I have searched on the documentation and found some information about creating images but I am unsure as to what exactly I will need to achieve this task.
Yes. Using an Autoscaling Group, you can create a launch configuration that will launch you instances. Using CodeDeploy, you would link your deployment group to the auto-scaling group.
See Integrating AWS CodeDeploy with Auto Scaling
AWS CodeDeploy supports Auto Scaling, an AWS service that can launch
Amazon EC2 instances automatically according to conditions you define.
These conditions can include limits exceeded in a specified time
interval for CPU utilization, disk reads or writes, or inbound or
outbound network traffic. Auto Scaling terminates the instances when
they are no longer needed. For more information, see What Is Auto
Scaling?.
Assuming you set your desired/minimum instances to 0, then the default state of the ASG will be to have no instances.
When you application needs an instance spun up, it would simply change the desired instance value to 1. When your application is completed with the instance, it would set your desired count to 0 again, thereby terminating that instance.
To develop this setup, start by running your instance normally (manually) and get the application deployment working. When that works, then create your auto scaling group. Finally, update your deployment group to refer to the ASG so that your code is deployed when you have scaling events.