Amazon ECR Interview Questions

1. What is Amazon Elastic Container Registry (Amazon ECR)?

Amazon Elastic Container Registry (Amazon ECR) is a fully-managed Docker container registry that makes it easy to store, manage, and deploy Docker container images. With Amazon ECR, you can host your own images in the same infrastructure used by Amazon ECS, and can use IAM policies to control access to your images.

Using Amazon ECR, you can store and manage Docker images in a private repository, allowing you to securely store and manage the lifecycle of your applications. You can also easily push and pull images to and from your repositories using the Docker command line interface (CLI), and easily deploy your images to Amazon ECS tasks or Kubernetes clusters using the AWS Management Console or the AWS CLI.

In addition to being a fully-managed service, Amazon ECR integrates seamlessly with other AWS services such as Amazon ECS, Amazon EKS, and AWS CodePipeline, making it easy to build, test, and deploy containerized applications at scale.

2. Why should I use Amazon ECR?

There are several reasons why you might want to consider using Amazon ECR for your container registry needs:

1. It is fully managed: Amazon ECR is a fully-managed service, meaning that it handles the underlying infrastructure and maintenance for you. This can save you time and resources that you would otherwise have to spend on maintaining your own registry.
2. It integrates with other AWS services: Amazon ECR integrates seamlessly with other AWS services such as Amazon ECS, Amazon EKS, and AWS CodePipeline, making it easy to build, test, and deploy containerized applications at scale.
3. It is secure: Amazon ECR provides fine-grained access controls using AWS Identity and Access Management (IAM) policies, allowing you to control who has access to your images.
4. It is highly available: Amazon ECR is designed to be highly available, with multiple Availability Zones (AZs) and automatic replication of images across AZs to ensure that your images are always available when you need them.
5. It is cost-effective: Amazon ECR offers a pay-as-you-go pricing model, so you only pay for what you use. It also offers free storage for the first 500 MB and free image pushes and pulls for the first 100,000 image requests per month.

3. Can Amazon ECR host public container images?

No, Amazon Elastic Container Registry (Amazon ECR) is a private container registry, which means that the images stored in it are only accessible to the AWS account owner and users with the appropriate IAM permissions. It is not possible to make images stored in Amazon ECR public or accessible to users outside of your AWS account.

If you want to host a public container registry, there are several other options available, such as Docker Hub, which is a public registry provided by Docker, Inc. that allows users to store and share Docker images with the community. Other options include quay.io, which is a public container registry provided by Red Hat, and GitHub Container Registry, which is a public registry provided by GitHub.

4. What is the difference between Amazon ECR public and private repositories?

Amazon Elastic Container Registry (Amazon ECR) does not offer public repositories. All repositories in Amazon ECR are private, which means that they are only accessible to the AWS account owner and users with the appropriate IAM permissions.

The term “public repository” is often used to refer to a container registry that is accessible to anyone on the internet, regardless of whether they have an account with the registry provider. In contrast, a “private repository” is only accessible to a specific group of users, usually those with an account with the registry provider and the appropriate permissions.

In Amazon ECR, all repositories are private by default, and you can use IAM policies to control access to your images. This allows you to securely store and manage the lifecycle of your applications and ensures that only authorized users can access your images.

5. What is the pricing for Amazon ECR?

Amazon Elastic Container Registry (ECR) is a fully-managed Docker container registry that makes it easy for developers to store, manage, and deploy Docker container images.

There is no charge for using Amazon ECR to store your Docker images. You only pay for the data you store in your repositories and data transfer fees. The following fees apply to Amazon ECR:

• Data stored in your repositories: $0.10 per GB per month.
• Data transfer:
  • Data transferred out of Amazon ECR to the internet: $0.09 per GB.
  • Data transferred between Amazon ECR and Amazon EC2 within the same AWS Region: no charge.
  • Data transferred between Amazon ECR and other AWS services within the same AWS Region: no charge.

You can also choose to use Amazon ECR with Amazon ECS, which is a fully-managed container orchestration service. In this case, you would pay for the cost of using Amazon ECS, which includes the cost of running your containers, as well as any additional resources that you use, such as Amazon EC2 instances or Amazon Elastic Block Store (EBS) volumes.

It’s worth noting that Amazon ECR is just one of the many services offered by Amazon Web Services (AWS). If you’re using multiple AWS services, you’ll be billed for all of the services you use, in addition to any applicable data transfer fees.

6. Is Amazon ECR a Global Service?

Yes, Amazon Elastic Container Registry (ECR) is a global service that is available in multiple regions around the world. This means that you can store, manage, and deploy Docker container images from Amazon ECR in any region where the service is available.

When you create an Amazon ECR repository, you can specify the region where you want to store your images. This allows you to store your images in a region that is close to your users, which can help reduce latencies and improve the performance of your applications.

It’s worth noting that when you push or pull an image from an Amazon ECR repository, the data transfer is free within the same region. However, if you transfer data between regions, you will be charged for the data transfer.

7. What compliance capabilities can I enable on Amazon ECR?

Amazon Elastic Container Registry (ECR) provides a number of compliance capabilities that you can enable to ensure that your container images meet your organization’s compliance requirements.

Here are some of the compliance capabilities that you can enable on Amazon ECR:

• Image Scanning: You can enable image scanning on your Amazon ECR repositories to detect vulnerabilities in your container images. Image scanning uses the open-source vulnerability scanner, Clair, to identify known vulnerabilities in your images and provides a report that you can use to fix any issues.
• Image Signing: You can use image signing to ensure that the container images in your Amazon ECR repositories have not been tampered with. Image signing allows you to create digital signatures for your container images, which can be verified by others to ensure the integrity of the images.
• Compliance Reports: You can use Amazon ECR compliance reports to monitor your repositories for compliance with industry standards and regulations, such as the Payment Card Industry Data Security Standard (PCI DSS) and the Health Insurance Portability and Accountability Act (HIPAA).
• AWS Artifact: You can use AWS Artifact to access AWS compliance documents and reports, including service-specific reports, such as the Amazon ECR Compliance Report.

Questions on Using Amazon ECR

8. How do I get started using Amazon ECR?

To get started using Amazon Elastic Container Registry (ECR), you will need to perform the following steps:

1. Sign up for an AWS account: If you don’t already have an AWS account, you will need to create one. You can sign up for an AWS account at https://aws.amazon.com/.
2. Set up your environment: You will need to set up your environment by installing and configuring the AWS CLI, Docker, and Amazon ECR credential helper. You can find instructions for setting up your environment in the Amazon ECR documentation.
3. Create a repository: You can create a repository in Amazon ECR to store your Docker images. You can create a repository through the AWS Management Console, the AWS CLI, or the Amazon ECR API.
4. Build and push your image: Once you have created a repository, you can build your Docker image and push it to the repository using the Docker CLI.
5. Deploy your image: After you have pushed your image to Amazon ECR, you can deploy it using Amazon Elastic Container Service (ECS), Amazon Elastic Kubernetes Service (EKS), or any other container orchestration service.

9. Can I access Amazon ECR inside a VPC?

Yes, you can access Amazon Elastic Container Registry (ECR) inside a virtual private cloud (VPC) by using a VPC endpoint. A VPC endpoint allows you to securely connect to Amazon ECR over the Amazon VPC network, without the need to traverse the public internet.

To access Amazon ECR inside a VPC, you will need to perform the following steps:

1. Create a VPC endpoint: You can create a VPC endpoint for Amazon ECR through the AWS Management Console, the AWS CLI, or the Amazon ECR API.
2. Configure your security group: You will need to configure the security group associated with your VPC endpoint to allow inbound traffic from your Amazon EC2 instances or other resources that will be accessing Amazon ECR.
3. Connect to Amazon ECR: After you have created a VPC endpoint and configured your security group, you can connect to Amazon ECR from within your VPC using the Docker CLI or the Amazon ECR API.

10. What’s the best way to manage my ECS Repositories and Images?

There are several ways that you can manage your Amazon Elastic Container Registry (ECR) repositories and images, depending on your needs and preferences. Here are a few options:

1. AWS Management Console: You can use the AWS Management Console to create, delete, and manage your ECR repositories, as well as view and manage the images in your repositories.
2. AWS CLI: You can use the AWS Command Line Interface (CLI) to perform a variety of tasks, such as creating and deleting repositories, pushing and pulling images, and managing image tags.
3. Amazon ECR API: You can use the Amazon ECR API to programmatically manage your ECR repositories and images. You can use the API to perform tasks such as creating and deleting repositories, pushing and pulling images, and managing image tags.
4. Docker CLI: You can use the Docker CLI to push and pull images from your ECR repositories, as well as manage image tags.
5. Third-party tools: There are also a number of third-party tools that you can use to manage your ECR repositories and images. For example, you can use tools such as Jenkins or GitHub Actions to automate the build and deployment of your container images.

11. How do I publicly share an image using Amazon ECR?

To publicly share an image stored in Amazon Elastic Container Registry (ECR), you can use the aws ecr get-login command to retrieve an authentication token that allows you to pull the image from your repository. You can then share the authentication token and the repository URI with others, and they will be able to pull the image from your repository.

Here are the steps to publicly share an image stored in Amazon ECR:

1. Retrieve the authentication token: Run the following command to retrieve an authentication token that allows you to pull the image from your repository:

aws ecr get-login --no-include-email

This command will output a docker login the command that you can use to authenticate your Docker client.

2. Share the authentication token and repository URI: Share the output of the aws ecr get-login command, along with the URI of your repository, with the people you want to give access to your image. For example, if your repository URI is 123456789012.dkr.ecr.us-east-1.amazonaws.com/my-repository, you would share the following information with them:

docker login -u AWS -p <authentication_token> 123456789012.dkr.ecr.us-east-1.amazonaws.com/my-repository

3. Pull the image: The people you shared the information with can use the docker login command and the repository URI to authenticate their Docker client and pull the image from your repository. For example:

docker pull 123456789012.dkr.ecr.us-east-1.amazonaws.com/my-repository:latest

12. Can I use a Custom alias for my ECR Public Images?

Yes, you can use a custom alias for your Amazon Elastic Container Registry (ECR) public images by creating a repository policy that grants pull permissions to the aws account. This will allow anyone to pull images from your repository, and you can use a custom alias to make it easier for others to access your images.

Here are the steps to use a custom alias for your AWS ECR public images:

1. Create a repository policy: First, you will need to create a repository policy that grants pull permissions to the aws account. You can do this through the AWS Management Console, the AWS CLI, or the Amazon ECR API.

Here is an example of a repository policy that grants pull permissions to the aws account:

{
  "Version": "2008-10-17",
  "Statement": [
    {
      "Sid": "AllowPublicPull",
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::aws:user/root"
      },
      "Action": [
        "ecr:GetDownloadUrlForLayer",
        "ecr:BatchGetImage",
        "ecr:BatchCheckLayerAvailability"
      ]
    }
  ]
}

2. Set the repository policy: After you have created the repository policy, you can set it on your repository using the AWS Management Console, the AWS CLI, or the Amazon ECR API.
3. Share the repository URI and custom alias: Once the repository policy is in place, you can share the repository URI and your custom alias with others, and they will be able to pull images from your repository. For example, if your repository URI is 123456789012.dkr.ecr.us-east-1.amazonaws.com/my-repository and your custom alias is my-alias, you can share the following information with others:

docker pull 123456789012.dkr.ecr.us-east-1.amazonaws.com/my-alias:latest

13. How do I pull a public image from Amazon ECR?

To pull a public image from Amazon Elastic Container Registry (ECR), you will need to have the repository URI and an authentication token that allows you to access the repository. You can then use the docker pull command to pull the image from the repository.

Here are the steps to pull a public image from Amazon ECR:

1. Retrieve the repository URI and authentication token: You will need to get the repository URI and an authentication token from the person who owns the repository. The repository URI is the unique identifier for the repository, and the authentication token is a temporary token that allows you to access the repository.
2. Authenticate the Docker client: Use the docker login command and the repository URI and authentication token to authenticate your Docker client. For example:

docker login -u AWS -p <authentication_token> <repository_uri>

3. Pull the image: Use the docker pull command and the repository URI to pull the image from the repository. For example:

docker pull <repository_uri>:latest

14. Does Amazon ECR work with Amazon ECS?

Yes, Amazon Elastic Container Registry (ECR) is fully integrated with Amazon Elastic Container Service (ECS), which is a fully-managed container orchestration service. You can use Amazon ECR to store, manage, and deploy Docker images to Amazon ECS, and Amazon ECS will take care of running your containers on a cluster of Amazon EC2 instances or AWS Fargate.

Here are the steps to use Amazon ECR with Amazon ECS:

1. Create a repository in Amazon ECR: You can create a repository in Amazon ECR to store your Docker images. You can create a repository through the AWS Management Console, the AWS CLI, or the Amazon ECR API.
2. Build and push your image: Once you have created a repository, you can build your Docker image and push it to the repository using the Docker CLI.
3. Create a task definition: You will need to create a task definition in Amazon ECS that specifies the Docker image to use and the resources to allocate to your containers. You can create a task definition through the AWS Management Console, the AWS CLI, or the Amazon ECS API.
4. Create a service: You can create a service in Amazon ECS to run and manage your containers. A service allows you to specify the number of tasks to run and the desired running state of your tasks. You can create a service through the AWS Management Console, the AWS CLI, or the Amazon ECS API.

15. Does Amazon ECR work with AWS Elastic Beanstalk?

Yes, you can use Amazon Elastic Container Registry (ECR) with AWS Elastic Beanstalk to store, manage, and deploy Docker images to Elastic Beanstalk environments. Elastic Beanstalk is a fully-managed service that makes it easy to deploy and run applications in the cloud.

To use Amazon ECR with Elastic Beanstalk, you will need to perform the following steps:

1. Create a repository in Amazon ECR: You can create a repository in Amazon ECR to store your Docker images. You can create a repository through the AWS Management Console, the AWS CLI, or the Amazon ECR API.
2. Build and push your image: Once you have created a repository, you can build your Docker image and push it to the repository using the Docker CLI.
3. Create an Elastic Beanstalk environment: You will need to create an Elastic Beanstalk environment to run your Docker containers. You can create an environment through the AWS Management Console, the AWS CLI, or the Elastic Beanstalk API.
4. Deploy your image: After you have created an Elastic Beanstalk environment, you can use the AWS Management Console, the AWS CLI, or the Elastic Beanstalk API to deploy your Docker image to the environment. Elastic Beanstalk will take care of running your containers on a cluster of Amazon EC2 instances.

Amazon ECR Interview Questions

15. What version of Docker Engine does Amazon ECR support?

Amazon Elastic Container Registry (ECR) supports the latest version of Docker Engine, as well as all previous versions that are still supported by Docker Inc. This means that you can use any version of Docker Engine that is compatible with your operating system to push and pull images from Amazon ECR.

You can find the list of supported Docker Engine versions in the Docker documentation. It’s worth noting that Docker Inc. typically only supports the current and previous minor versions of Docker Engine, so it’s a good idea to keep your Docker Engine up to date to ensure that you have access to the latest features and security updates.

16. What version of the Docker Registry API does Amazon ECR support?

Amazon Elastic Container Registry (ECR) supports version 2 of the Docker Registry API. The Docker Registry API is a set of HTTP-based APIs that allow you to push and pull images from a Docker registry, such as Amazon ECR.

You can use the Docker Registry API to perform a variety of tasks, such as listing the images in a repository, uploading and downloading images, and managing image tags. The Docker Registry API is used by the Docker CLI and other tools to interact with Docker registries.

17. Does Amazon ECR replicate images across AWS Regions?

By default, Amazon Elastic Container Registry (ECR) does not replicate images across AWS Regions. When you push an image to an Amazon ECR repository, it is stored in a single Region, and it is only accessible from that Region.

However, you can use the AWS CLI to replicate your images across Regions. The AWS CLI provides the aws ecr command, which allows you to copy images between repositories in different Regions.

To replicate an image from one Region to another, you can use the aws ecr batch-get-image and aws ecr put-image commands. You can also use the aws ecr describe-images command to list the images in a repository, and the aws ecr delete-image command to delete an image from a repository.

18. Can I use Amazon ECR within local and on-premises environments?

Yes, you can use Amazon Elastic Container Registry (ECR) within local and on-premises environments by installing the Docker daemon on your local machine or on-premises server. You can then use the Docker CLI to push and pull images from Amazon ECR.

To use Amazon ECR within a local or on-premises environment, you will need to perform the following steps:

1. Install the Docker daemon: You will need to install the Docker daemon on your local machine or on-premises server. You can find instructions for installing the Docker daemon in the Docker documentation.
2. Set up your environment: You will need to set up your environment by installing and configuring the AWS CLI and the Amazon ECR credential helper. You can find instructions for setting up your environment in the Amazon ECR documentation.
3. Authenticate the Docker daemon: You can use the aws ecr get-login command to retrieve an authentication token that allows the Docker daemon to access your Amazon ECR repositories. You can then use the docker login command to authenticate the Docker daemon.
4. Push and pull images: You can use the Docker CLI to push and pull images from your Amazon ECR repositories. For example, you can use the docker push and docker pull commands to push and pull images from your repositories.

19. Does the Amazon ECR public gallery provide AWS-published images?

The Amazon Elastic Container Registry (ECR) public gallery is a collection of Docker images that are publicly available for use. The gallery includes a variety of images, including those published by AWS and those published by third parties.

The AWS-published images in the ECR public gallery include a variety of popular open-source applications and tools, such as WordPress, Drupal, PostgreSQL, and MongoDB. These images are pre-configured and optimized for use with AWS, and are maintained by AWS.

You can browse the ECR public gallery to see the available images and use the docker pull command to pull an image from the gallery. You can also use the aws ecr describe-images command to list the images in the gallery, and the aws ecr batch-get-image command to download multiple images at once.

20. Does Amazon ECR support Federated Access?

Yes, Amazon Elastic Container Registry (ECR) supports federated access, which allows you to use your existing identity provider (IdP) to access your Amazon ECR repositories.

To use federated access with Amazon ECR, you will need to set up a trust relationship between your IdP and AWS, and then use the AWS Management Console or the AWS CLI to assign IAM roles to your IdP users or groups. You can then use your IdP credentials to access your Amazon ECR repositories.

You can use a variety of IdPs with Amazon ECR, including Active Directory, Okta, and other SAML 2.0-compliant IdPs.

21. What version of the Docker Image Manifest specification does Amazon ECR support?

Amazon Elastic Container Registry (ECR) supports version 2 of the Docker Image Manifest specification. The Docker Image Manifest is a JSON document that describes the contents and layout of a Docker image. It includes information about the layers that make up the image, the image configuration, and the metadata for the image.

You can use the Docker Image Manifest to manage the contents of your Docker images and to share information about your images with others. The Docker CLI and other tools use the Docker Image Manifest to interact with Docker images and registries.

22. Does Amazon ECR support the Open Container Initiative (OCI) format?

Yes, Amazon Elastic Container Registry (ECR) supports the Open Container Initiative (OCI) format. The OCI is an open-source project that provides a set of standards for container image formats and runtime execution. The OCI defines the OCI Image Format, which is a specification for storing and distributing container images.

You can use the OCI Image Format with Amazon ECR to store and distribute your container images. Amazon ECR supports the OCI Image Format through the Docker CLI, which can push and pull images in OCI format to and from Amazon ECR.

23. Will Amazon ECR automatically build images from a Dockerfile?

No, Amazon Elastic Container Registry (ECR) does not provide a built-in capability to automatically build images from a Dockerfile. Instead, you will need to use a separate tool or service to build your images from a Dockerfile, and then push the resulting images to Amazon ECR.

There are several tools and services that you can use to build images from a Dockerfile, including the Docker CLI, AWS CodeBuild, and Jenkins. You can use these tools to build your images locally or in the cloud, and then push the resulting images to Amazon ECR.

Here are the steps to build and push an image to Amazon ECR using the Docker CLI:

1. Install the Docker daemon: You will need to install the Docker daemon on your local machine or in the cloud. You can find instructions for installing the Docker daemon in the Docker documentation.
2. Set up your environment: You will need to set up your environment by installing and configuring the AWS CLI and the Amazon ECR credential helper. You can find instructions for setting up your environment in the Amazon ECR documentation.
3. Build your image: Use the docker build command and a Dockerfile to build your image. The docker build command will create an image from the instructions in the Dockerfile.
4. Tag your image: Use the docker tag command to add a tag to your image. The tag will be used to identify the image in Amazon ECR.
5. Push your image: Use the docker push command to push your image to Amazon ECR. The docker push command will upload your image to the specified repository in Amazon ECR.

Questions on Amazon ECR Security

24. Can I share my images across AWS accounts?

Yes, you can share your images across AWS accounts by using Amazon Elastic Container Registry (ECR) cross-account image sharing. ECR cross-account image sharing allows you to share your images with other AWS accounts by creating a resource policy that grants permissions to the other accounts.

To share your images across AWS accounts, you will need to perform the following steps:

1. Create a resource policy: You can use the aws ecr set-repository-policy command to create a resource policy for your repository that grants permissions to other AWS accounts. The resource policy is a JSON document that specifies the permissions to grant and the accounts to grant them to.
2. Share the repository URI: You will need to share the repository URI with the other AWS accounts if you want to grant access. The repository URI is the unique identifier for your repository, and it is used to access the repository.
3. Authenticate the Docker daemon: The other AWS accounts will need to authenticate their Docker daemons to access your repository. They can use the aws ecr get-login command to retrieve an authentication token that allows their Docker daemons to access your repository.
4. Pull the image: The other AWS accounts can use the docker pull command and the repository URI to pull the image from your repository.

25. Does Amazon ECR Scan Container Images for Vulnerabilities?

Yes, Amazon Elastic Container Registry (ECR) provides a capability called Amazon ECR Image Scanning that allows you to scan your container images for vulnerabilities. Amazon ECR Image Scanning uses the open-source vulnerability scanner, Clair, to scan your images and identify known vulnerabilities in the packages and libraries that are included in your images.

To use Amazon ECR Image Scanning, you will need to perform the following steps:

1. Enable image scanning: You can enable image scanning for your repository through the AWS Management Console, the AWS CLI, or the Amazon ECR API.
2. Push your image: Use the Docker CLI to push your image to your repository. Amazon ECR will automatically scan your image for vulnerabilities when it is pushed to the repository.
3. View the scan results: You can view the scan results through the AWS Management Console, the AWS CLI, or the Amazon ECR API. The scan results will include a list of the vulnerabilities that were identified in your image, along with information about the severity of each vulnerability.

Amazon ECR Image Scanning is a useful tool for ensuring the security and compliance of your container images.

26. How does Amazon ECR help ensure that container images are secure?

There are several ways in which Amazon Elastic Container Registry (ECR) helps ensure that container images are secure:

1. Image scanning: Amazon ECR provides a capability called Amazon ECR Image Scanning, which allows you to scan your container images for vulnerabilities. Amazon ECR Image Scanning uses the open-source vulnerability scanner, Clair, to scan your images and identify known vulnerabilities in the packages and libraries that are included in your images.
2. Image signing: Amazon ECR supports Docker Content Trust, which allows you to sign your images to ensure their authenticity and integrity. Docker Content Trust uses cryptographic signatures to verify that an image has not been tampered with and that it was built from trusted source code.
3. Image deletion protection: Amazon ECR provides a capability called image deletion protection, which allows you to prevent the accidental deletion of your images. Image deletion protection prevents images from being deleted, even if the repository is deleted or the image is untagged.
4. IAM policies: Amazon ECR supports IAM policies, which allow you to control access to your repositories and images. You can use IAM policies to grant or deny access to specific AWS accounts or users, and to specify the actions that are allowed or denied on your repositories and images.

27. How can I use AWS Identity and Access Management (IAM) for permissions?

You can use AWS Identity and Access Management (IAM) to manage permissions for your Amazon Elastic Container Registry (ECR) repositories and images. IAM is a web service that allows you to create and manage users and groups, and to apply permissions to AWS resources.

To use IAM for permissions with Amazon ECR, you will need to perform the following steps:

1. Create IAM users and groups: You can use the AWS Management Console, the AWS CLI, or the IAM API to create IAM users and groups. You can then add users to groups to manage permissions for multiple users at once.
2. Create IAM policies: You can use IAM policies to specify the permissions that you want to grant or deny for your Amazon ECR repositories and images. An IAM policy is a JSON document that specifies the actions that are allowed or denied, and the resources that the policy applies.
3. Attach policies to users or groups: You can attach IAM policies to users or groups to grant or deny permissions to specific users or groups. You can attach policies through the AWS Management Console, the AWS CLI, or the IAM API.
4. Use IAM to authenticate: You can use IAM to authenticate your users when they access your Amazon ECR repositories and images. You can use the AWS Management Console, the AWS CLI, or the IAM API to authenticate your users.

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