If I create a custom AMI for an EBS backed EC2 instance after installing numerous applications and making lot of config changes to the EC2 instance like IP Tables, httpd.conf file etc...
Will the custom AMI image capture all those config changes and/or installed applications so that I can use it to launch exact functioning copy of the Custom AMI originating EC2 Instance?
Anything done after launching an EC2 instance will be independent of what the original AMI had. There isn't a relationship among the instances which use the same AMI as well; except that they all were materialised from a single AMI - the individual / independent changes in the Instances ( AMI ) would be in silos.
Coming back to your point; after making numerous changes; you would need to create an image AMI out of the running instance where the changes have been made. Going forward you can use the AMI to create new instances. Already created instances wouldn't reflect any new changes.
This is where the tools like Ansible, Chef, Puppet come into picture.
Related
Is there a way to backup users along with software created in AWS.
context:I am currently learning ansible and shutting down those instances created after some time..Everyday i have to recreate again users,,install anisble after relaunching those instances
The natural way to backup EC2 instances is through snapshots. You can also create custom AMI which will simplify launching new instances with all the per-installed software of yours, along with its users and all the settings.
I have completely understood the concept of Auto-Scaling in AWS. My only question is, what AMI will the launch configuration use while in production environment?
According to my understanding Image of existing instance should be used. Lets say I have used an image of existing instance.
What if there are any changes in existing instance in future? In this scenario we have to update the AMI.
Is there any process to automate this process?
When you create new AMI and set it in a new launch configuration (LC; LC can't be edited) or new version of a launch template (LT), then you will have to update the ASG configuration with the new LC/LT.
However, ASG by default will not update existing instances with new LC/LT. Only new instance that ASG launches will have the new LC/LT, and subsequently, the new AMI. Therefore, you will end up with ASG in which part of instances is running old AMI, and the other part is running new AMI.
You can deal with this in two commonly used ways:
Create your LC/LT and ASG using CloudFormation and specify UpdatePolicy. The update policy will be triggered when LC/LT changes, and existing instances in ASG will be updated based on the rules you specify in the policy.
Perform blue/green deployment of your ASG. How to perform the deployment is described and explained in details in an excellent AWS white paper:
Blue/Green Deployments on AWS
Auto scaling uses AMIs which are a point in time snapshot of your instance. Any changes made thereafter will not be applied to the AMI.
If you want any change to your base image you will need to recreate an image and roll it out across your Launch Configuration/Launch Template again.
There are many tools people use to provision the configuration of instances for AMIs such as Ansible, Chef and Puppet.
AWS also launched an automation tool for building images last year, the EC2 Image Builder
For some additional reading take a look at the golden ami pipeline.
In AWS cloud formation, i use the cloud former tool. I can use that tool to create a cloud formation template from existing resources. And then use the template to create a stack. I tested with that tool. It can work, (as in it can create instances with same memory size, with same volume size, same VPC settings, and auto start the instances). But there is no files in the volume.
Do i have to create a snapshot of the existing volume, create a new volume from the snapshot, attach it to the newly created instance, and copy the files manually ?
Or is there any better way ?
Do i have to create a snapshot of the existing volume, create a new volume from the snapshot, attach it to the newly created instance, and copy the files manually ?
Cloudformation is provisioning resources, but is not responsible for provisioning the contents of those resources - that you have to do yourself.
You can leverage the EC2 Userdata to manually pull files from S3 or other repos as the instance boots.
Or is there any better way ?
If you want to share data between applications, EFS is always an option. In your case, though, using Userdata might be effective.
If you wish to launch new EC2 instances with software automatically loaded, there are basically two choices:
Use a pre-configured AMI, or
Use a startup script to load the software
Pre-configured AMI
An Amazon Machine Image (AMI) is a copy of a disk. When a new EC2 instance is launched, an AMI is selected and the boot disk (and optionally other disks) are automatically pre-loaded with the contents of the AMI.
A common practice is to boot an EC2 instance and configure it as desired. Then, create an AMI. Thereafter, when a new EC2 instance is required for the application, launch it using the pre-built AMI.
There are also tools available to automate the building of an AMI, such as Netflix Aminator and Packer.
Benefits: New machine boots quickly, fully-configured.
Issues: Need to create a new AMI whenever you update your software.
Use a startup script to load the software
When an Amazon EC2 instance is launched from a standard Amazon-provided AMI (eg Amazon Linux, Microsoft Windows), software on the AMI automatically looks at the User Data passed to an EC2 instance. If the User Data contains a startup script, the script will be executed -- but only the first time that an instance is launched. This is an excellent way to install software on the instance.
You are responsible for writing the script. The script should install whatever tools, software and data you want on the instance.
Benefits: Updating your software? Just launch a new instance and the script will install the latest version of your software (assuming you have written the script to always point to the latest version).
Issues: It takes longer to launch the new instance, since the software is being installed.
I have created Auto scaling group in AWS using a customized AMI. Now to rollout my new code I need to either update all instances running but then if a new instance comes up it won't be updated. So, I need a way to update AMI. One way could be creating new AMI and Autoscaling group.
Thanks in advance.
This is one way to go about it:
Spin up a stand-alone instance using the AMI
Make changes
Stop instance
Create new AMI from this instance
Create a new Launch Configuration that uses the new AMI
Update the Autoscaling Group to use the new Launch Configuration
Slowly terminate the old instances in the Autoscaling Group, and let them be automatically replaced with instances using the new AMI
Of course all this is a pain to deal with manually every time you need to make a change. Elastic Beanstalk and CloudFormat both provide mechanisms to deal with this in a more automated way.
If you are just changing the code you are deploying to your servers, then there are other ways to handle this, such as using AWS CodeDeploy. You could also update the running servers in some automated or manual fashion, and configure the AMI such that any new instances that are created will go get the latest code on startup.
I am having AWS EC2 instance.
I want to load user data on every boot up of EC2 instance.
Whether this is possible or i have to create new instance each time to execute user data?
Multiple options:
create a custom AMI with the users and co figurations you want. Easiest way to do this is to create an EBS backed instance, do the setup, and the. Select the dashboard option to create an AMI from the instance.
have your settings on a remote source(s3 for instance), which your instance is setup to pull and execute/add/configure.
For a single instance, the AMI works well. For a larger environment, configs management like kickstart, puppet, chef, cfengine, or similar will be better.