I'm trying to determine how to remove an instance from several applications (freeIPA, Chef, service discovery) from within an AWS autoscaling group but I'm finding that there's no reliable way to determine if an instance is simply stopping (sometimes our admins will take an instance out of the ASG for analysis) vs terminating. If the instance is stopped then I would like to retain the ability to have it stay connected to our LDAP and other systems. Anyone know a good way to do this?
Is the instance EBS backed or using instance store?
if instance store, you cannot really stop it (only terminate it)
Have you looked at the EC2 API (via aws-sdk maybe)? (looks like describe-instances and looking at reservations should do the trick here)
http://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeInstances.html
I determined that the best way for me to do this was to use the ASG alarms (specifically the EC2_TERMINATE alarm). This effectively allows me to take no action if an instance is stopping and fire off a script if it is determined that the instance is terminating.
Related
I would like to try to setup AWS Launch Template, or just Spot request (persistance) and I need automatically attach my specific volume.
The main idea - spot instance will be process data and store it in a separate volume. When Spot will die, another Spot should be requested automatically (which will be built from an image with predefined software) and data should continue processing automatically (and again, storing in my second volume).
But, I can`t setup it in AWS console, so, looks like it is not possible. Am I wrong? Is it possible in some another way?
The same according IP address - I would like to have the same IP address for any of "versions" of Spot (after recreating for example)
It is possible to attach and detach Elastic IP using AWS CLI to achieve what you want.
However there are other possible workarounds in case you do not want to script AWS CLI :
Using Route53 you can define an A record with TTL of 60 seconds if you can accept few minutes of transition. That way you get to use a domain to access your underlying instance instead.
Setup a ALB and forward the request to the EC2 fleet
I've an ECS cluster with running one task for my backend instance. I would like to be able to stop/start the EC2 instance whenever I want. Is it possible?? I was trying to stop instance directly but it terminates after few second when stopped and after that new instance is created automatically. I tried to change the Auto Scale Group to match desired=min=0 capacity but when I do that the instance gets auto terminated. I just want to turn off the Ec2 instance when its not needed to be used but at the same time I want data to persist betweet turning on and off. I am fighting with this for a few days now and wasn't able to achieve my goals.
Also how to link EBS volume with VOLUME /root/.local/share/XYZ from docker file image to persist the data from the XYZ folder
I would suggest you to do modifications in autoscaling group, when you want to turn off instance put 0 in auto scaling and when you want to turn on change value in autoscaling,
... you can do that with aws cli , and you can shcdule the period also by putting aws cli command in cron job
I would suggest using EFS. Here is an article from AWS on how to persist data from ECS containers using EFS.
Using Amazon EFS to Persist Data from Amazon ECS Containers
Start/Stop instances and auto-scale don't really fit together.
Auto-scale is specifically designed to solve scalein/scaleout.
One way to address this could be using customized termination policy (but I never tried this in ECS setup).
One note though, if your customized termination policy never terminates the instances and you continue adding instances to keep always, you might get good amount EC2 bill.
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.
How can I create a policy that will allow a single user in a group to create an ec2 instance in a particular VPC and AZ?
I need it to also be destroyable by the same user or destroyed when idle for more than 24 hours.
You can't. What you can do, however, is script the logic yourself to provide equivalent functionality. A good starting point would be to google AWS SDK.
This is not possible via IAM policies nor other configurations.
You would have to write your own application with this logic, which would launch the instance on the user's behalf and then terminate it later (although that depends on your definition of 'when idle'). The user would interact with this application when they want to launch the instance, rather than interacting directly with AWS.
To be more specific:
It is possible to limit the number of EC2 instances that an AWS Account can have running simultaneously (the default is 20)
It is not possible to limit the number of instances a single user may launch. Either they have permissions to launch an instance with certain attributes, or they don't, but this cannot be limited by whether/what instances are already running.
Some ways you could create a self-terminating instance:
A CloudWatch Alarm could terminate an instance when CPU or Network drops below a certain level for a period of time (eg when Network Out is below 10KB over a half-our period).
A script on the instance itself could decide when to Shutdown the instance. If the instance is launched with Shutdown Behaviour set to Terminate, then shutting down the instance from within the instance will cause it to terminate.
You could create an application that regularly looks at running instances and terminates them 24 hours after being launched. This could be triggered by a Scheduled Task (Windows) or cron job (Linux).
A variation on the previous option is to add a Tag to the instance to indicate when to terminate it. An application could regularly check the tag to determine which instances to terminate.
I am looking at using AWS auto-scaling to scale my infrastructure up and down based on various performance metrics (CPU, etc.). I understand how to set this up; however, I don't like that instances are terminated rather than stopped when it is scaled down. This means that when I scale back up, I have to start from scratch with a new instance and re-install my software, etc. I'd rather just start/stop my instances as needed rather than create/terminate. Is there a way to do this?
No, it is not possible to Stop an instance under Auto Scaling. When a Scaling Policy triggers the removal of an instance, Auto Scaling will always Terminate the instance.
However, here's some ideas to cope with the concept of Termination...
Option 1: Use pre-configured AMIs
You can configure an Amazon EC2 instance with your desired software, data and settings. Then, select the EC2 instance in the Management Console and choose the Create Image action. This will create a new Amazon Machine Image (AMI). You can then configure Auto Scaling to use this AMI when launching a new instance. Each new instance will contain exactly the same disk contents.
It's worth mentioning that EBS starts up very quickly from an AMI. Instead of copying the whole AMI to the boot disk, it copies it across on "first access". This means the new instance can start-up immediately rather than waiting for the whole disk to be copied.
Option 2: Use a startup (User Data) script
Each Amazon EC2 instance has a User Data field, which is accessible from the instance. A script can be passed through the User Data field, which is then executed when the instance starts. The script could be used to install software, download data and configure the instance.
The script could do something very simple, like download a configuration script from a source code repository, then execute the script. This means that machine configuration can be centrally managed and version-controlled. Want to update your app? Just launch a new instance with the updated script and throw away the old instance (which is much easier than "updating" an app).
Option 3: Add/Remove instances to an Auto Scaling group
Rather than using Scaling Policies to Launch/Terminate instances for an Auto Scaling group, it is possible to attach/detach specific instances. Thus, you could 'simulate' auto scaling:
When you want to scale-down, detach an instance from the Auto Scaling group, then stop it.
When you want to add an instance, start the instance then attach it to the Auto Scaling group.
This would require your own code, but it is very simple (basically two API calls). You would be responsible for keeping track of which instance to attach/detach.
You can suspend scaling processes, see documentation here:
https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-suspend-resume-processes.html#as-suspend-resume
Add that instance to Scale in protection and then stop the instance then it will not delete your instance as it's having the scale in protection.
Actually you have three official AWS options to reboot or even stop an instance which belongs to an Auto Scaling Group:
Put the instance into the Standby state
Detach the instance from the group
Suspend the health check process
Ref.: https://aws.amazon.com/premiumsupport/knowledge-center/reboot-autoscaling-group-instance/
As of April 2021:
Option 4: Use Warm Pools and an Instance Reuse Policy
By default, Amazon EC2 Auto Scaling terminates your instances when your Auto Scaling group scales in. Then, it launches new instances into the warm pool to replace the instances that were terminated.
If you want to return instances to the warm pool instead, you can specify an instance reuse policy. This lets you reuse instances that are already configured to serve application traffic.
This mostly automates option 3 from John's answer.
Release announcement: https://aws.amazon.com/blogs/compute/scaling-your-applications-faster-with-ec2-auto-scaling-warm-pools/
Documentation: https://docs.aws.amazon.com/autoscaling/ec2/userguide/ec2-auto-scaling-warm-pools.html
This is to expand a little on #mwalling's answer, because that is the right direction, but needs a little extra work to prevent instance termination.
There is now a way to stop or hibernate scaled in instances!
By default AWS Autoscaling scale in policy is to terminate an instance. Even if you have a warm pool configured. Autoscaling will create a fresh instance to put into the warm pool. Presumably to make sure you start with a fresh machine every time. However, with a instance reuse policy you can make AWS Autoscaling either stop or hibernate a running instance and store that instance in the warm pool.
Advantages include:
Local caches stay populated (use hibernate for in memory cache).
Burstable EC2 instances (those types with T*) keep built up burst credits instead of the newly created instance that have limited or no credits.
Practical example:
We use a burstable EC2 instance for CI/CD work that we scale to 0 instances outside working hours. With a reuse policy our local image repository stays populated with the most important Docker images. Also we keep the built up credit from the previous day and that speeds up automatic jobs we run first thing every morning.
How to implement:
There's currently no way of doing this completely via the management console. So you will need to use AWS CLI or SDK.
First create a warm pool as described in the AWS Documentation
Then execute this command to add a reuse policy:
aws autoscaling put-warm-pool --auto-scaling-group-name <Name-of-autoscaling-group> --instance-reuse-policy ReuseOnScaleIn=true
Reference docs for the command: AWS CLI Autoscaling put-warm-pool documentation
Flow diagram of possible life cycles of EC2 instances:
Image from AWS Documentation: Lifecycle state transitions for instances in a warm pool