I do not now much about spot instances but I'm wondering whether I have to create a new EBS volume with every instance or is it possible to start an instance with a previously launched EBS volume ?
Amazon provides an option to do the same.
Delete on termination false spot instances
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Scenario
I currently have an EC2 instance with a root EBS volume attached to it of 30gb and i have some files stored in that EBS
If i delete the EC2 instance and have delete on termination false then EBS persists.
Desired outcome
I want to provision a new EC2 (provisioned by auto scaling group) instance such that it uses the old EBS volume as its root volume which was detached as a result of me terminating the old instance
Note
I want to have the liberty of choosing OS of newly provisioned EC2 so creating an AMI does not work
You cannot directly launch a new Amazon EC2 instance with an existing Amazon EBS volume. Instead, you would need to:
Launch a new Amazon EC2 instance with a new root volume
Stop the instance
Detach the root volume
Attach the 'old' EBS volume
Start the instance
Storing data in root EBS volume might be a bad idea to start with.
Consider one of the following:
Mount another EBS volume to the instance to store required data only.
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-using-volumes.html
best performance, highest cost/effort, but your application doesn't
change a bit.
Create EFS and mount it to your instances. https://docs.aws.amazon.com/efs/latest/ug/mounting-fs.html -
reasonable effort, minimal if any changes to the application.
Store data in S3. Ideal from price standpoint; requires changes to the application.
I have cloud formation template that creates two EBS volumes and I am attaching those volumes to instance using aws ec2 attach-volumes from user data, also I have auto scaling group setup, so when I update stack with different instance type and it launches new instance, volumes are not attached.
I checked logs and it says volumes are not available, I know why because the terminated instance is using those volumes when ASG launches new one, is there any way that I could reuse those volumes.
Your problem is that the EBS volumes are attached to a different EC2 instance when you want to attach them.
One solution is to write a program (e.g. Python) that monitors the EBS volumes. The program is launched in UserData. Once the volumes become available the program attaches them and exits.
when i add ASG update policy with min instance in service = 0 and min=1, desired=1 and max=1 it is working because ASG terminates old instance before it launches new instance when you have min instances in service=0
I have an auto-scaling group with 2 instances.
Every time an instance is launched an EBS volume is attached to it. When it is replaced/terminated is the EBS volume deleted ?
I want to keep a tight budget on my account and I dont want to have volumes lingering and pay for them.
You can configure it both ways. If you are using the web interface to configure the launch configuration when you get to Storage you will see this:
You just need to check the "Delete on Termination" checkbox on the right, whenever an instance is terminated the EBS volume associated will be deleted as well.
I have several AMIs that developers use to spin up instances. These AMI do not have "delete on termination" set on all their EBS volumes. At times terminating instances launched using these AMIs has the unintended consequence of leaving behind orphan EBS volumes. Unfortunately, "blessing" a new AMI for general use is quite an ordeal. Is it possible to edit an existing AMI to turn on "delete on termination" or is the only way forward to create a new AMI with the proper settings?
It is not possible to modify the "Delete on termination" value on an existing AMI.
So you have 2 choices:
Launch an EC2 instance from your AMI and produce a new AMI with the appropriate "Delete on Terminate" value, or
Modify the value when you launch the new EC2 instance.
Once the instance is running you can call modifyAttribute (modify-instance-attribute in the CLI) on the attribute blockDeviceMapping.
aws ec2 modify-instance-attribute --instance-id i-a3ef245 --block-device-mappings "[{\"DeviceName\": \"/dev/sda\",\"Ebs\":{\"DeleteOnTermination\":false}}]"
You can see an example here: http://www.petewilcock.com/how-to-modify-deletion-on-termination-flag-for-ebs-volume-on-running-ec2-instance/
There is no such features.
In addition, I think you misundestand the purpose of AWS web console EC2 EBS Volumes vs snapshot.
When you launch an instances, a EBS Volume is assign to the instance(if it is a EBS base instance like t2., c3.) , once you terminate it, that assoicated volume will be deleted.
Unless you create a EBS volumes that attach to a instances, that is another story. An attached volumes will stay even the instance it attached to is deleted, this is intended design as EBS volumes is network storage anyway, it should allow you to detach/attach to different instances dynamically.
On the other hand, your user may create snapshot(s) for their instances, which store under the Snapshot portion. This is part that will stay, even you terminate the original instance. Once you deleted the original instance, the volume it point do will be "orphaned".
It is a good practice to create a snapshot for instance as backup, but it will go wilds if you don't have a standard policy to handle it. No automation can help a process nature issues.
You MUST enforce a policy and standard for your developer to follow as well, e.g. backup cycle, tag for snapshot, etc.
Does the life cycle of an EBS volume is coupled with the life cycle of an EC2 (meaning terminating an EC2 will terminate EBS volume as well)?
No , terminating instance will not terminate EBS volume attached with it , thus you wont lose your DATA .
It depends on how the EBS volume was created. If it was created during the EC2 instance launch with the "Delete on Termination" flag set, it will be deleted, otherwise it will just remain as a unattached volume.
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/block-device-mapping-concepts.html