# Building a custom AWS ParallelCluster AMI
When using the AWS ParallelCluster command line interface (CLI) or API, you only pay for the AWS resources that are created when you create or update AWS ParallelCluster images and clusters. For more information, see [AWS services used by AWS ParallelCluster](aws-services-v3.md).
**Important**
If you build a custom AMI, you must repeat the steps that you used to create your custom AMI with each new AWS ParallelCluster release.
Before reading further, we recommend that you first review the [Custom bootstrap actions](custom-bootstrap-actions-v3.md) section. Determine if the modifications that you want to make can be scripted and supported with future AWS ParallelCluster releases.
Even though building a custom AMI in general isn't ideal, there are specific scenarios where building a custom AMI for AWS ParallelCluster is necessary. This tutorial covers how to build a custom AMI for these scenarios.
**Prerequisites**
+ AWS ParallelCluster [is installed](install-v3-parallelcluster.md).
+ The AWS CLI [is installed and configured.](https://docs.aws.amazon.com/cli/latest/userguide/getting-started-install.html)
+ You have an [Amazon EC2 key pair](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-key-pairs.html).
+ You have an IAM role with the [permissions](iam-roles-in-parallelcluster-v3.md#iam-roles-in-parallelcluster-v3-example-user-policies) required to run the [`pcluster`](pcluster-v3.md) CLI and build images.
## How to customize the AWS ParallelCluster AMI
There are two ways to build a custom AWS ParallelCluster AMI. One of these two methods is to build a new AMI using the AWS ParallelCluster CLI. Another method requires that you to make manual modifications to build a new AMI that's available under your AWS account.
## Build a custom AWS ParallelCluster AMI
If you have a customized AMI and software, you can apply the changes that are needed by AWS ParallelCluster on top of it. AWS ParallelCluster relies on the EC2 Image Builder service to build customized AMIs. For more information, see the [Image Builder User Guide](https://docs.aws.amazon.com/imagebuilder/latest/userguide/what-is-image-builder.html).
Key points:
+ The process takes about 1 hour. This time can vary if there are additional [`Build`](Build-v3.md) / [`Components`](Build-v3.md#Build-v3-Components) to be installed at build time.
+ The AMI is tagged with the versions of the main components. These include the kernel, scheduler, and [EFA](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/efa.html) driver. A subset of the component versions are also reported in the AMI description.
+ Starting from AWS ParallelCluster 3.0.0, a new set of CLI commands can be used to manage the lifecycle of images. This includes [`build-image`](pcluster.build-image-v3.md), [`list-images`](pcluster.list-images-v3.md), [`describe-image`](pcluster.describe-image-v3.md), and [`delete-image`](pcluster.delete-image-v3.md).
+ This method is repeatable. You can re-run it to keep AMIs updated (for example, OS updates), and then use them when you update an existing cluster.
**Note**
If you use this method in the AWS China Partition, you might get network errors. For example, you might see these errors from the `pcluster build-image` command when it downloads packages from GitHub or from an OS repository. If this happens, we recommend that you use one of the following alternative methods:
Follow the [Modify an AWS ParallelCluster AMI](#modify-an-aws-parallelcluster-ami-v3) approach that bypasses this command.
Build the image in another Partition and Region, such as `us-east-1`, and then store/restore it to move it to the China Region. For more information, see [Store and restore an AMI using S3](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ami-store-restore.html) in the *Amazon EC2 User Guide*.
Steps:
1. Configure your AWS account credentials so that the AWS ParallelCluster client can make calls to AWS API operations on your behalf. For a list of the required permissions, see [AWS Identity and Access Management permissions in AWS ParallelCluster](iam-roles-in-parallelcluster-v3.md).
1. Create a basic *build image* configuration file. To do this, specify the [`InstanceType`](Build-v3.md#yaml-build-image-Build-InstanceType) to be used to build the image and the [`ParentImage`](Build-v3.md#yaml-build-image-Build-ParentImage). These are used as the starting point to create the AMI. For more information about optional build parameters, see [Image Configuration](image-builder-configuration-file-v3.md).
```
Build:
InstanceType: {{}}
ParentImage: {{}}
```
1. Use the CLI command [`pcluster build-image`](pcluster.build-image-v3.md) to build an AWS ParallelCluster AMI starting from the AMI that you provide as the base.
```
$ pcluster build-image --image-id {{IMAGE_ID}} --image-configuration {{IMAGE_CONFIG.yaml}} --region {{REGION}}
{
"image": {
"imageId": "IMAGE_ID",
"imageBuildStatus": "BUILD_IN_PROGRESS",
"cloudformationStackStatus": "CREATE_IN_PROGRESS",
"cloudformationStackArn": "arn:aws:cloudformation:us-east-1:123456789012:stack/IMAGE_ID/abcd1234-ef56-gh78-ij90-1234abcd5678",
"region": "us-east-1",
"version": "3.15.0"
}
}
```
**Warning**
`pcluster build-image` uses the default VPC. If you delete the default VPC using AWS Control Tower or AWS Landing Zone, the subnet ID must be specified in the image configuration file. For more information, see [`SubnetId`](HeadNode-v3.md#yaml-HeadNode-Networking-SubnetId).
For a list of other parameters, see the [`pcluster build-image`](pcluster.build-image-v3.md) command reference page. The results of the preceding command are as follows:
+ A CloudFormation stack is created based on the image configuration. The stack includes all of the EC2 Image Builder resources required for the build.
+ The created resources include the official Image Builder AWS ParallelCluster components that custom Image Builder components can be added to. For more information, see [ Create a custom component with Image Builder](https://docs.aws.amazon.com/imagebuilder/latest/userguide/create-component.html) in the *EC2 Image Builder User Guide*.
+ EC2 Image Builder launches a build instance, applies the AWS ParallelCluster cookbook, installs the AWS ParallelCluster software stack, and performs necessary configuration tasks. The AWS ParallelCluster cookbook is used to build and bootstrap AWS ParallelCluster.
+ The instance is stopped and a new AMI is created from it.
+ Another instance is launched from the newly created AMI. During the test phase, EC2 Image Builder runs tests that are defined in the Image Builder components.
+ If the build is successful, the stack is deleted. If the build fails, the stack is retained and available for inspection.
1. You can monitor the status of the build process by running the following command. After the build completes, you can run it to retrieve the AMI ID given in the response.
```
$ pcluster describe-image --image-id {{IMAGE_ID}} --region {{REGION}}
# BEFORE COMPLETE
{
"imageConfiguration": {
"url": "https://parallelcluster-1234abcd5678efgh-v1-do-not-delete.s3.amazonaws.com/parallelcluster/3.15.0/images/IMAGE_ID-abcd1234efgh5678/configs/image-config.yaml?...",
},
"imageId": "IMAGE_ID",
"imagebuilderImageStatus": "BUILDING",
"imageBuildStatus": "BUILD_IN_PROGRESS",
"cloudformationStackStatus": "CREATE_IN_PROGRESS",
"cloudformationStackArn": "arn:aws:cloudformation:us-east-1:123456789012:stack/IMAGE_ID/abcd1234-ef56-gh78-ij90-1234abcd5678",
"region": "us-east-1",
"version": "3.15.0",
"cloudformationStackTags": [
{
"value": "3.15.0",
"key": "parallelcluster:version"
},
{
"value": "IMAGE_ID",
"key": "parallelcluster:image_name"
},
...
],
"imageBuildLogsArn": "arn:aws:logs:us-east-1:123456789012:log-group:/aws/imagebuilder/ParallelClusterImage-IMAGE_ID",
"cloudformationStackCreationTime": "2022-04-05T21:36:26.176Z"
}
# AFTER COMPLETE
{
"imageConfiguration": {
"url": "https://parallelcluster-1234abcd5678efgh-v1-do-not-delete.s3.us-east-1.amazonaws.com/parallelcluster/3.15.0/images/IMAGE_ID-abcd1234efgh5678/configs/image-config.yaml?Signature=..."
},
"imageId": "IMAGE_ID",
"imageBuildStatus": "BUILD_COMPLETE",
"region": "us-east-1",
"ec2AmiInfo": {
"amiName": "IMAGE_ID 2022-04-05T21-39-24.020Z",
"amiId": "ami-1234stuv5678wxyz",
"description": "AWS ParallelCluster AMI for alinux2, kernel-4.14.238-182.422.amzn2.x86_64, lustre-2.10.8-5.amzn2.x86_64, efa-1.13.0-1.amzn2.x86_64, dcv-2021.1.10598-1.el7.x86_64, slurm-20-11-8-1",
"state": "AVAILABLE",
"tags": [
{
"value": "2021.3.11591-1.el7.x86_64",
"key": "parallelcluster:dcv_version"
},
...
],
"architecture": "x86_64"
},
"version": "3.15.0"
}
```
1. To create your cluster, enter the AMI ID in the [`CustomAmi`](Scheduling-v3.md#yaml-Scheduling-SlurmQueues-Image-CustomAmi) field in your cluster configuration.
**Troubleshooting and monitoring AMI creation process**
Image creation completes in about an hour. You can monitor the process by running the [`pcluster describe-image`](pcluster.describe-image-v3.md) command or log retrieval commands.
```
$ pcluster describe-image --image-id {{IMAGE_ID}} --region {{REGION}}
```
The [`build-image`](pcluster.build-image-v3.md) command creates a CloudFormation stack with all the Amazon EC2 resources that are required to build the image, and launches the EC2 Image Builder process.
After running the [`build-image`](pcluster.build-image-v3.md) command, it's possible to retrieve CloudFormation stack events by using [`pcluster get-image-stack-events`](pcluster.get-image-stack-events-v3.md). You can filter results with the `--query` parameter to see the latest events. For more information, see [Filtering AWS CLI output](https://docs.aws.amazon.com/cli/latest/userguide/cli-usage-filter.html) in the *AWS Command Line Interface User Guide*.
```
$ pcluster get-image-stack-events --image-id {{IMAGE_ID}} --region {{REGION}} --query "events[0]"
{
"eventId": "ParallelClusterImage-CREATE_IN_PROGRESS-2022-04-05T21:39:24.725Z",
"physicalResourceId": "arn:aws:imagebuilder:us-east-1:123456789012:image/parallelclusterimage-IMAGE_ID/3.15.0/1",
"resourceStatus": "CREATE_IN_PROGRESS",
"resourceStatusReason": "Resource creation Initiated",
"resourceProperties": "{\"InfrastructureConfigurationArn\":\"arn:aws:imagebuilder:us-east-1:123456789012:infrastructure-configuration/parallelclusterimage-abcd1234-ef56-gh78-ij90-1234abcd5678\",\"ImageRecipeArn\":\"arn:aws:imagebuilder:us-east-1:123456789012:image-recipe/parallelclusterimage-IMAGE_ID/3.15.0\",\"DistributionConfigurationArn\":\"arn:aws:imagebuilder:us-east-1:123456789012:distribution-configuration/parallelclusterimage-abcd1234-ef56-gh78-ij90-1234abcd5678\",\"Tags\":{\"parallelcluster:image_name\":\"IMAGE_ID\",\"parallelcluster:image_id\":\"IMAGE_ID\"}}",
"stackId": "arn:aws:cloudformation:us-east-1:123456789012:stack/IMAGE_ID/abcd1234-ef56-gh78-ij90-1234abcd5678",
"stackName": "IMAGE_ID",
"logicalResourceId": "ParallelClusterImage",
"resourceType": "AWS::ImageBuilder::Image",
"timestamp": "2022-04-05T21:39:24.725Z"
}
```
After about 15 minutes, the stack events appear in the log event entry related to Image Builder creation. You can now list image log streams and monitor the Image Builder steps by using [`pcluster list-image-log-streams`](pcluster.list-image-log-streams-v3.md) and [`pcluster get-image-log-events`](pcluster.get-image-log-events-v3.md) commands.
```
$ pcluster list-image-log-streams --image-id {{IMAGE_ID}} --region {{REGION}} \
--query 'logStreams[*].logStreamName'
"3.15.0/1"
]
$ pcluster get-image-log-events --image-id {{IMAGE_ID}} --region {{REGION}} \
--log-stream-name 3.15.0/1 --limit 3
{
"nextToken": "f/36295977202298886557255241372854078762600452615936671762",
"prevToken": "b/36295977196879805474012299949460899222346900769983430672",
"events": [
{
"message": "ExecuteBash: FINISHED EXECUTION",
"timestamp": "2022-04-05T22:13:26.633Z"
},
{
"message": "Document arn:aws:imagebuilder:us-east-1:123456789012:component/parallelclusterimage-test-abcd1234-ef56-gh78-ij90-1234abcd5678/3.15.0/1",
"timestamp": "2022-04-05T22:13:26.741Z"
},
{
"message": "TOE has completed execution successfully",
"timestamp": "2022-04-05T22:13:26.819Z"
}
]
}
```
Continue to check with the [`describe-image`](pcluster.describe-image-v3.md) command until you see the `BUILD_COMPLETE` status.
```
$ pcluster describe-image --image-id {{IMAGE_ID}} --region {{REGION}}
{
"imageConfiguration": {
"url": "https://parallelcluster-1234abcd5678efgh-v1-do-not-delete.s3.us-east-1.amazonaws.com/parallelcluster/3.15.0/images/IMAGE_ID-abcd1234efgh5678/configs/image-config.yaml?Signature=..."
},
"imageId": "IMAGE_ID",
"imageBuildStatus": "BUILD_COMPLETE",
"region": "us-east-1",
"ec2AmiInfo": {
"amiName": "IMAGE_ID 2022-04-05T21-39-24.020Z",
"amiId": "ami-1234stuv5678wxyz",
"description": "AWS ParallelCluster AMI for alinux2, kernel-4.14.238-182.422.amzn2.x86_64, lustre-2.10.8-5.amzn2.x86_64, efa-1.13.0-1.amzn2.x86_64, dcv-2021.1.10598-1.el7.x86_64, slurm-20-11-8-1",
"state": "AVAILABLE",
"tags": [
{
"value": "2021.3.11591-1.el7.x86_64",
"key": "parallelcluster:dcv_version"
},
...
],
"architecture": "x86_64"
},
"version": "3.15.0"
}
```
If you need to troubleshoot a custom AMI creation issue, create an archive of the image logs as described in following steps.
It's possible to archive the logs in an Amazon S3 bucket or in a local file, depending on the `--output` parameter.
```
$ pcluster export-image-logs --image-id {{IMAGE_ID}} --region {{REGION}} \
--bucket {{BUCKET_NAME}} --bucket-prefix {{BUCKET_FOLDER}}
{
"url": "https://BUCKET_NAME.s3.us-east-1.amazonaws.com/BUCKET-FOLDER/IMAGE_ID-logs-202209071136.tar.gz?AWSAccessKeyId=..."
}
$ pcluster export-image-logs --image-id {{IMAGE_ID}} \
--region {{REGION}} --bucket {{BUCKET_NAME}} --bucket-prefix {{BUCKET_FOLDER}} --output-file /tmp/archive.tar.gz
{
"path": "/tmp/archive.tar.gz"
}
```
The archive contains the CloudWatch Logs Streams related to the Image Builder process and CloudFormation stack events. The command might take several minutes to run.
**Managing Custom AMIs**
Starting from AWS ParallelCluster 3.0.0, a new set of commands has been added in the CLI to build, monitor, and manage the image lifecycle. For more information about the commands, see [pcluster commands](pcluster-v3.md).
## Modify an AWS ParallelCluster AMI
This method consists of modifying an official AWS ParallelCluster AMI by adding customization on top of it. The base AWS ParallelCluster AMIs are updated with new releases. These AMIs have all of the components that are required for AWS ParallelCluster to function when it's installed and configured. You can start with one of these as your base.
Key points:
+ This method is faster than the [`build-image`](pcluster.build-image-v3.md) command. However, it's a manual process and not automatically repeatable.
+ With this method, you don't have access to the log retrieval and image lifecycle management commands that are available through the CLI.
Steps:
------
#### [ New Amazon EC2 console ]
1. Find the AMI that corresponds to the specific AWS Region that you use. To find it, use the [`pcluster list-official-images`](pcluster.list-official-images-v3.md) command with the `--region` parameter to select the specific AWS Region and `--os` and `--architecture` parameters to filter for the desired AMI with the OS and architecture that you want to use. From the output, retrieve the Amazon EC2 Image ID.
1. Sign in to the AWS Management Console and open the Amazon EC2 console at [https://console.aws.amazon.com/ec2/](https://console.aws.amazon.com/ec2/).
1. In the navigation pane, choose **Images**, and then **AMIs**. Search for the retrieved EC2 Image ID, select the AMI, and choose **Launch instance from AMI**.
1. Scroll down and choose your **Instance type**.
1. Choose your **Key pair** and **Launch Instance**.
1. Log in to your instance using the OS user and your SSH key.
1. Manually customize your instance to meet your requirements.
1. Run the following command to prepare your instance for AMI creation.
```
sudo /usr/local/sbin/ami_cleanup.sh
```
1. From the console, choose **Instance state** and **Stop instance**.
Navigate to **Instances**, choose the new instance, select **Instance state**, and **Stop instance**.
1. Create a new AMI from the instance using the Amazon EC2 console or AWS CLI [create-image](https://docs.aws.amazon.com/cli/latest/reference/ec2/create-image.html).
**From the Amazon EC2 console**
1. Choose **Instances** in the navigation pane.
1. Choose the instance that you created and modified.
1. In **Actions**, choose **Image** and then **Create image**.
1. Choose **Create Image**.
1. Enter the new AMI ID in the [`CustomAmi`](Scheduling-v3.md#yaml-Scheduling-SlurmQueues-Image-CustomAmi) field in your cluster configuration and create a cluster.
------
#### [ Old Amazon EC2 console ]
1. Find the AWS ParallelCluster AMI that corresponds to the specific AWS Region that you use. To find it you can use the [`pcluster list-official-images`](pcluster.list-official-images-v3.md) command with the `--region` parameter to select the specific AWS Region and `--os` and `--architecture` parameters to filter for the desired AMI with the OS and architecture that you want to use. From the output you can retrieve the Amazon EC2 Image ID.
1. Sign in to the AWS Management Console and open the Amazon EC2 console at [https://console.aws.amazon.com/ec2/](https://console.aws.amazon.com/ec2/).
1. In the navigation pane, choose **Images**, and then **AMIs**. Set the filter for **Public images** and search for the retrieved EC2 Image ID, select the AMI, and choose **Launch**.
1. Choose your instance type and select **Next: Configure Instance Details** or **Review and Launch** to launch your instance.
1. Choose **Launch**, select your **Key pair**, and **Launch Instances**.
1. Log into your instance using the OS user and your SSH key. For more information, navigate to **Instances**, select the new instance and **Connect**.
1. Manually customize your instance to meet your requirements.
1. Run the following command to prepare your instance for AMI creation:
```
sudo /usr/local/sbin/ami_cleanup.sh
```
1. From the Amazon EC2 console, choose **Instances** in the navigation pane, select your new instance and choose **Actions**, **Instance State** and **Stop**.
1. Create a new AMI from the instance using the Amazon EC2 console or AWS CLI [create-image](https://docs.aws.amazon.com/cli/latest/reference/ec2/create-image.html).
**From the Amazon EC2 console**
1. Choose **Instances** in the navigation pane.
1. Choose the instance you created and modified.
1. In **Actions**, choose **Image** and then **Create Image**.
1. Choose **Create Image**.
1. Enter the new AMI ID in the [`CustomAmi`](Scheduling-v3.md#yaml-Scheduling-SlurmQueues-Image-CustomAmi) field in your cluster configuration and create a cluster.
------