We have an application with long running processes which prevents us from being able to use Elastic Beanstalk to properly scale the environment. In fact no metric scaling would be useful for us and what we really need to be able to do is the following....
On demand, programatically, create a new EC2 instance which is a duplicate of a specific EC2 "template" instance (That template instance would be an EC2 running IIS with specific code deployed to it, probably via beanstalk).
On demand, programatically, destroy a specific instance
Based on specific events we would need to perform the above actions via our .NET code base.
I get the feeling that we should be able to do this with cloudformation templates but i dont see any clear documentation to handle this.
Any advise or direction would be greatly appreciated.
Not sure about doing this through .Net code, but you can create an auto scaling group in AWS console and that will take care of the scaling requirements in a maintainable way.
Log on to AWS and navigate to Management Console
First create an EC2 Instance with proper instance type (say, t2.large) or whatever your sizing is.
Then have IIS installed and get your app running on this instance.
Now create a new Image from the above running EC2 Instance
Create a new Auto Scaling Group and add the above new Image
Create a Launch Configuration for the Auto Scaling Group (AWS Console will redirect you to do this step when you try to setup Auto Scaling Group).
Once the Auto Scaling Group is setup, navigate to Auto Scaling Policy and add a policy there. For example, you can create a policy to 'add 1 instance on CPU utilization of 80% or more for 2 consecutive times'.
Also make sure Min is 0 and Max is say, 2. This is upto you to decide based on your scaling requirements. If you have Min as 1, it automatically creates the first instance. If Min is 0, no new instances will be created until the threshold in the Auto Scale Policy is met.
Also create a Scale Down Policy to remove instances when there is a low CPU utilization.
Note: I took CPU utilization as an example to describe the scenario. You can have any metrics as per your choice and architectural needs.
Related
I am running a flask python program on EC2 which is under Load Balancer and autoscaling. In a scenario where is load increases on one Ec2 it creates another and if newly scaled Ec2 has been idle or not utilized it scales in or terminates it. The problem here is if a single user is accessing newly scaled instance which hardly takes any CPU utilization how autoscaling group will realize that it idle and if it doesn't it will terminate it leaving downtime for that user.
I have two scenarios in mind that it checks for a particular program for a amount of time in EC2 if it is running then don't, otherwise terminate it.
I see Step scaling policy but there option is only for CPU utilization that is hardly consumed if there is a single user, not even 0.1 %.
Can someone please tell me whats the best option for me and if these two options are possible then how to do it? I have been trying to ask developers since many days but could not get reliable answers in my case.
Amazon EC2 Auto-scaling does not know which of your instances are 'in use'.
Also, the decision to terminate an instance is typically made on a metric across all instances (eg CPU Utilization), rather than a metric on a specific instance.
When Auto Scaling decides to remove an instance from the Auto Scaling group, it picks an instance as follows:
It picks an Availability Zone with the most instances (to keep them balanced)
It then selects an instance based on the Termination Policy
See also: Control which Auto Scaling instances terminate during scale in - Amazon EC2 Auto Scaling
When using a Load Balancer with Auto Scaling, traffic going to the instance that will be terminated is 'drained', allowing a chance for the instance to complete existing requests.
You can further prevent an instance from terminating while it is still "in use"by implementing Amazon EC2 Auto Scaling lifecycle hooks that allow your own code to delay the Termination.
Or, if all of this is unsatisfactory, you can disable the automatic selection of an instance to terminate and instance have your own code call TerminateInstanceInAutoScalingGroup - Amazon EC2 Auto Scaling to terminate a specific instance of your choosing.
For an overview of Auto Scaling, I recommend this video from the AWS Reinvent conference: AWS re:Invent 2019: Capacity management made easy with Amazon EC2 Auto Scaling (CMP326-R1) - YouTube
I have one infra that use amazon elastic beanstalk to deploy my application.
I need to scale my app adding some spot instances that EB do not support.
So I create a second autoscaling from a launch configuration with spot instances.
The autoscaling use the same load balancer created by beanstalk.
To up instances with the last version of my app, I copy the user data from the original launch configuration (created with beanstalk) to the launch configuration with spot instances (created by me).
This work fine, but:
how to update spot instances that have come up from the second autoscaling when the beanstalk update instances managed by him with a new version of the app?
is there another way so easy as, and elegant, to use spot instances and enjoy the benefits of beanstalk?
UPDATE
Elastic Beanstalk add support to spot instance since 2019... see:
https://docs.aws.amazon.com/elasticbeanstalk/latest/relnotes/release-2019-11-25-spot.html
I was asking this myself and found a builtin solution in elastic beanstalk. It was described here as follows:
Add a file under the .ebextensions folder, for our setup we’ve named the file as spot_instance.config (the .config extension is
important), paste the content available below in the file
https://gist.github.com/rahulmamgain/93f2ad23c9934a5da5bc878f49c91d64
The value for EC2_SPOT_PRICE, can be set through the elastic beanstalk environment configuration. To disable the usage of spot
instances, just delete the variable from the environment settings.
If the environment already exists and the above settings are updates, the older auto scaling group will be destroyed and a new one
is created.
The environment then submits a request for spot instances which can be seen under Spot Instances tab on the EC2 dashboard.
Once the request is fulfilled the instance will be added to the new cluster and auto scaling group.
You can use Spot Advisor tool to ascertain the best price for the instances in use.
A price point of 30% of the original price seems like a decent level.
I personally would just use the on-demand price for the given instance type given this price is the upper boundary of what you would be willing to pay. This reduces the likelihood of being out-priced and thus the termination of your instances.
This might be not the best approach for production systems as it is not possible to split between a number of on-demand instances and an additional number of spot instances and there might be a small chance that there are no spot instances available as someone else is buying the whole market with high bids.
For production use cases I would look into https://github.com/AutoSpotting/AutoSpotting, which actively manages all your auto-scaling groups and tries to meet the balance between the lowest prices and a configurable number or percentage of on-demand instances.
As of 25th November 2019, AWS natively supports using Spot Instances with Beanstalk.
Spot instances can be enabled in the console by going to the desired Elastic Beanstalk environment, then selecting Configuration > Capacity and changing the Fleet composition to "Spot instance enabled".
There you can also set options such as the On-Demand vs Spot percentage and the instance types to use.
More information can be found in the Beanstalk Auto Scaling Group support page
Here at Spotinst, we were dealing with exactly that dilemma for our customers.
As Elastic Beanstalk creates a whole stack of services (Load Balancers, ASG’s, Route 53 access point etc..) that are tied together, it isn’t a simple task to manage Spots within it.
After a lot of research, we figured that removing the ASG will always be prone to errors as keeping the configuration intact gets complex. Instead, we simply replicate the ASG and let our Elastigroup and the ASG live side by side with all the scaling policies only affecting the Elastigroup and the ASG configuration updates feeding there as well.
With the instances running inside Elastigroup, you achieve managed Spot instances with full SLA.
Some of the benefits of running your Spot instances in Elastigroup include:
1) Our algorithm makes live choices for the best Spot markets in terms of price and availability whenever new instances spin up.
2) When an interruption happens, we predict it about 15 minutes in advance and take all the necessary steps to ensure (and insure) the capacity of your group.
3) In the extreme case that none of the markets have Spot availability, we simply fall back to an on-demand instance.
Since AWS clearly states that Beanstalk does not support spot instances out-of-the-box you need to tinker a bit with the thing. My customer wanted mixed environment (on-demand + spot) and full spot. What I created for my customer was the following (I had access to GUI only):
For the mixed env:
start the env with regular instance;
copy the respective launch configuration and chose spot instances during the process;
edit Auto Scaling Group and chose the lc you just edited + be sure to change Termination Policy to NewestInstance.
Such setup will allow you to have basic on-demand fleet (not-terminable) + some extra spots if required, e.g., higher-than-usual traffic. Remember that if you terminate the environment and recreate it then all of your edits will be removed.
For full spot env:
similar steps as before with one difference - terminate the running instance and wait for ASG to launch a new one. If you want it to do without downtime, just give an extra instance for the Desired number, wait for it to launch and then terminate on-demand one.
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.
Here's what I have in AWS:
Application ELB
Auto Scaling Group with 2 instances in different regions (Windows IIS servers)
Launch Config pointing to AMI_A
all associated back end stuff configured (VPC, subnets, security groups, ect)
Everything works. However, when I need to make an update or change to the servers, I am currently manually creating a new AMI_B, creating a new LaunchConfig using AMI_B, updating the AutoScalingGroup to use the new LaunchConfig, increasing min number of instances to 4, waiting for them to become available, then decreasing the number back to 2 to kill off the old instances.
I'd really love to automate this process. Amazon gave me some links to CLI stuff, and I'm able to script the AMI creation, create the LaunchConfig, and update the AutoScalingGroup...but I don't see an easy way to script spinning up the new instances.
After some searching, I found some CloudFormation templates that look like they'd do what I want, but most do more, and it's a bit confusing to me.
Should I be exploring CloudFormation? Is there a simple guide I can follow to get started? Or should I stay with the scripting I have started?
PS - sorry if this is a repeated question. Things change frequently at AWS, so sometimes the older responses may not be the current best answers.
You have a number of options to automate the process of updating the instances in an Auto Scaling Group to a new or updated Launch Configuration:
CloudFormation
If you do want to use CloudFormation to manage updates to your Auto Scaling Group's instances, refer to the UpdatePolicy attribute of the AWS::AutoScaling::AutoScalingGroup Resource for documentation, and the "What are some recommended best practices for performing Auto Scaling group rolling updates?" page in the AWS Knowledge Center for more advice.
If you'd also like to script the creation/update of your AMI within a CloudFormation resource, see my answer to the question, "Create AMI image as part of a cloudformation stack".
Note, however, that CloudFormation is not a simple tool- it's a complex, relatively low-level service for orchestrating AWS resources, and migrating your existing scripts to it will likely take some time investment due to its steep learning curve.
Elastic Beanstalk
If simplicity is most important, then I'd suggest you evaluate Elastic Beanstalk, which also supports both rolling and immutable updates during deployments, in a more fully managed, console-oriented, platform-as-a-service environment. Refer to my answer to the question, "What is the difference between Elastic Beanstalk and CloudFormation for a .NET project?" for further comparisons between CloudFormation and Elastic Beanstalk.
CodeDeploy
If you want a solution for updating instances in an auto-scaling group that you can plug into existing scripts, AWS CodeDeploy might be worth looking into. You install an agent on your instances, then trigger deployments through the API/CLI/Console and it manages deploying application updates to your fleet of instances. See Deploy an Application to an Auto Scaling Group Using AWS CodeDeploy for a complete tutorial. While CodeDeploy supports 'in-place' deployments and 'blue-green' deployments (see Working With Deployments for details), I think this service assumes an approach of swapping out S3-hosted application packages onto a static base AMI rather than replacing AMIs on each deployment. So it might not be the best fit for your AMI-swapping use case, but perhaps worth looking into anyway.
You want a custom Termination policy on the Auto Scaling Group.
OldestLaunchConfiguration. Auto Scaling terminates 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.
To customize a termination policy using the console
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
On the navigation pane, choose Auto Scaling Groups.
Select the Auto Scaling group.
For Actions, choose Edit.
On the Details tab, locate Termination Policies. Choose one or more
termination policies. If you choose multiple policies, list them in
the order that you would like them to apply. If you use the Default
policy, make it the last one in the list.
Choose Save.
On the CLI
aws autoscaling update-auto-scaling-group --auto-scaling-group-name my-asg --termination-policies "OldestLaunchConfiguration"
https://docs.aws.amazon.com/autoscaling/latest/userguide/as-instance-termination.html
We use Ansible's ec2_asg module for that purpose. There are replace_all_instances and replace_batch_size settings for that purpose. Per documentation:
In a rolling fashion, replace all instances that used the old launch configuration with one from the new launch configuration.
It increases the ASG size by C(replace_batch_size), waits for the new instances to be up and running.
After that, it terminates a batch of old instances, waits for the replacements, and repeats, until all old instances are replaced.
Once that's done the ASG size is reduced back to the expected size.
If you provide target_group_arns, module will check for health of instances in target groups before going to next batch.
Edit: in order to maintain desired number of instances, we first set min to desired.
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