Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Amazon Linux

Amazon Linux is provided by Amazon Web Services (Amazon). It is designed to provide a stable, secure, and high-performance execution environment for applications running on Amazon EC2. It also includes packages that enable easy integration with Amazon, including launch configuration tools and many popular Amazon libraries and tools. Amazon provides ongoing security and maintenance updates for all instances running Amazon Linux. Many applications developed on CentOS (and similar distributions) run on Amazon Linux.

Amazon Linux availability

Amazon provides Amazon Linux 2 and the Amazon Linux AMI. If you are migrating from another Linux distribution to Amazon Linux, we recommend that you migrate to Amazon Linux 2.

The last version of the Amazon Linux AMI, 2018.03, ended standard support on December 31, 2020. For more information, see the following blog post: Amazon Linux AMI end of life. If you are currently using the Amazon Linux AMI, we recommend that you migrate to Amazon Linux 2. To migrate to Amazon Linux 2, launch an instance or create a virtual machine using the current Amazon Linux 2 image. Install your applications, plus any required packages. Test your application, and make any changes required for it to run on Amazon Linux 2.

For more information, see Amazon Linux 2 and Amazon Linux AMI. For Amazon Linux Docker container images, see amazonlinux on Docker Hub.

Connect to an Amazon Linux instance

Amazon Linux does not allow remote root secure shell (SSH) by default. Also, password authentication is disabled to prevent brute-force password attacks. To enable SSH logins to an Amazon Linux instance, you must provide your key pair to the instance at launch. You must also set the security group used to launch your instance to allow SSH access. By default, the only account that can log in remotely using SSH is ec2-user; this account also has sudo privileges. If you enable remote root login, be aware that it is less secure than relying on key pairs and a secondary user.

Identify Amazon Linux images

Each image contains a unique /etc/image-id file that identifies it. This file contains the following information about the image:

Amazon Linux contains an /etc/system-release file that specifies the current release that is installed. This file is updated using yum and is part of the system-release RPM Package Manager (RPM).

Amazon Linux also contains a machine-readable version of /etc/system-release that follows the Common Platform Enumeration (CPE) specification; see /etc/system-release-cpe.

Amazon Linux 2

The following is an example of /etc/image-id for the current version of Amazon Linux 2.

[ec2-user ~]$ cat /etc/image-id
image_name="amzn2-ami-hvm"
image_version="2"
image_arch="x86_64"
image_file="amzn2-ami-hvm-2.0.20180810-x86_64.xfs.gpt"
image_stamp="8008-2abd"
image_date="20180811020321"
recipe_name="amzn2 ami"
recipe_id="c652686a-2415-9819-65fb-4dee-9792-289d-1e2846bd"

The following is an example of /etc/system-release for the current version of Amazon Linux 2.

[ec2-user ~]$ cat /etc/system-release
Amazon Linux 2

The following is an example of /etc/os-release for Amazon Linux 2.

[ec2-user ~]$ cat /etc/os-release
NAME="Amazon Linux"
VERSION="2"
ID="amzn"
ID_LIKE="centos rhel fedora"
VERSION_ID="2"
PRETTY_NAME="Amazon Linux 2"
ANSI_COLOR="0;33"
CPE_NAME="cpe:2.3:o:amazon:amazon_linux:2"
HOME_URL="https://amazonlinux.com/"

Amazon Linux AMI

The following is an example of /etc/image-id for the current Amazon Linux AMI.

[ec2-user ~]$ cat /etc/image-id
image_name="amzn-ami-hvm"
image_version="2018.03"
image_arch="x86_64"
image_file="amzn-ami-hvm-2018.03.0.20180811-x86_64.ext4.gpt"
image_stamp="cc81-f2f3"
image_date="20180811012746"
recipe_name="amzn ami"
recipe_id="5b283820-dc60-a7ea-d436-39fa-439f-02ea-5c802dbd"

The following is an example of /etc/system-release for the current Amazon Linux AMI.

[ec2-user ~]$ cat /etc/system-release
Amazon Linux AMI release 2018.03

Amazon command line tools

The following command line tools for Amazon integration and usage are included in the Amazon Linux AMI, or in the default repositories for Amazon Linux 2. For the complete list of packages in the Amazon Linux AMI, see Amazon Linux AMI 2017.09 Packages.

Amazon Linux 2 and the minimal versions of Amazon Linux (amzn-ami-minimal-* and amzn2-ami-minimal-*) do not always contain all of these packages; however, you can install them from the default repositories using the following command:

[ec2-user ~]$ sudo yum install -y package_name

For instances launched using IAM roles, a simple script has been included to prepare AWS_CREDENTIAL_FILE, JAVA_HOME, AWS_PATH, PATH, and product-specific environment variables after a credential file has been installed to simplify the configuration of these tools.

Also, to allow the installation of multiple versions of the API and AMI tools, we have placed symbolic links to the desired versions of these tools in /opt/aws, as described here:

Package repository

Amazon Linux 2 and the Amazon Linux AMI are designed to be used with online package repositories hosted in each Amazon EC2 Amazon Region. These repositories provide ongoing updates to packages in Amazon Linux 2 and the Amazon Linux AMI, as well as access to hundreds of additional common open-source server applications. The repositories are available in all Regions and are accessed using yum update tools. Hosting repositories in each Region enables us to deploy updates quickly and without any data transfer charges.

Amazon Linux 2 and the Amazon Linux AMI are updated regularly with security and feature enhancements. If you do not need to preserve data or customizations for your instances, you can simply launch new instances using the current AMI. If you need to preserve data or customizations for your instances, you can maintain those instances through the Amazon Linux package repositories. These repositories contain all the updated packages. You can choose to apply these updates to your running instances. Older versions of the AMI and update packages continue to be available for use, even as new versions are released.

To install packages, use the following command:

[ec2-user ~]$ sudo yum install package

For the Amazon Linux AMI, access to the Extra Packages for Enterprise Linux (EPEL) repository is configured, but it is not enabled by default. Amazon Linux 2 is not configured to use the EPEL repository. EPEL provides third-party packages in addition to those that are in the repositories. The third-party packages are not supported by Amazon. You can enable the EPEL repository with the following commands:

If you find that Amazon Linux does not contain an application you need, you can simply install the application directly on your Amazon Linux instance. Amazon Linux uses RPMs and yum for package management, and that is likely the simplest way to install new applications. You should always check to see if an application is available in our central Amazon Linux repository first, because many applications are available there. These applications can easily be added to your Amazon Linux instance.

To upload your applications onto a running Amazon Linux instance, use scp or sftp and then configure the application by logging on to your instance. Your applications can also be uploaded during the instance launch by using the PACKAGE_SETUP action from the built-in cloud-init package. For more information, see cloud-init.

Security updates

Security updates are provided using the package repositories as well as updated AMI security alerts are published in the Amazon Linux Security Center. For more information about Amazon security policies or to report a security problem, see Amazon Cloud Security.

Amazon Linux is configured to download and install critical or important security updates at launch time. We recommend that you make the necessary updates for your use case after launch. For example, you may want to apply all updates (not just security updates) at launch, or evaluate each update and apply only the ones applicable to your system. This is controlled using the following cloud-init setting: repo_upgrade. The following snippet of cloud-init configuration shows how you can change the settings in the user data text you pass to your instance initialization:

#cloud-config
repo_upgrade: security

The possible values for repo_upgrade are as follows:

The default setting for repo_upgrade is security. That is, if you don't specify a different value in your user data, by default, Amazon Linux performs the security upgrades at launch for any packages installed at that time. Amazon Linux also notifies you of any updates to the installed packages by listing the number of available updates upon login using the /etc/motd file. To install these updates, you need to run sudo yum upgrade on the instance.

Repository configuration

With Amazon Linux, AMIs are treated as snapshots in time, with a repository and update structure that always gives you the latest packages when you run yum update -y.

The repository structure is configured to deliver a continuous flow of updates that enable you to roll from one version of Amazon Linux to the next. For example, if you launch an instance from an older version of the Amazon Linux AMI (such as 2017.09 or earlier) and run yum update -y, you end up with the latest packages.

You can disable rolling updates by enabling the lock-on-launch feature. The lock-on-launch feature locks your instance to receive updates only from the specified release of the AMI. For example, you can launch a 2017.09 AMI and have it receive only the updates that were released prior to the 2018.03 AMI, until you are ready to migrate to the 2018.03 AMI.

To enable lock-on-launch in new instances, launch it with the following user data passed to cloud-init:

#cloud-config
repo_releasever: 2017.09

Extras library (Amazon Linux 2)

With Amazon Linux 2, you can use the Extras Library to install application and software updates on your instances. These software updates are known as topics. You can install a specific version of a topic or omit the version information to use the most recent version.

To list the available topics, use the following command:

[ec2-user ~]$ amazon-linux-extras list

To enable a topic and install the latest version of its package to ensure freshness, use the following command:

[ec2-user ~]$ sudo amazon-linux-extras install topic

To enable topics and install specific versions of their packages to ensure stability, use the following command:

[ec2-user ~]$ sudo amazon-linux-extras install topic=version topic=version

To remove a package installed from a topic, use the following command:

[ec2-user ~]$ sudo yum remove $(yum list installed | grep amzn2extra-topic | awk '{ print $1 }')

To disable a topic and make the packages inaccessible to the yum package manager, use the following command:

[ec2-user ~]$ sudo amazon-linux-extras disable topic

Amazon Linux 2 supported kernels

Supported kernel versions

Currently, Amazon Linux 2 (AL2) AMIs are available with kernel versions 4.14 and 5.10, with version 5.10 being a default. You also have an option of upgrading the kernel on AL2 to version 5.15 by using the extras repository. Note that an upgrade to 5.15 requires a reboot for the new kernel to take effect. Review new features and limitations of the kernel version 5.15 on AL2 before deciding whether an upgrade is required for your use case. If you require live patching support, we recommend you use AL2 AMI with kernel 5.10.

New features in kernel 5.15

Limitations for kernel 5.15

Instructions for installing kernel 5.15

You can upgrade to kernel 5.15 from both Amazon Linux 2 AMI with kernel 4.14 and AL2 AMI with kernel 5.10 using the following commands:

Support Timeframe

All Linux kernels available on Amazon Linux 2 (4.14, 5.10, and 5.15) will be supported until Amazon Linux 2 AMI reaches the end of standard support.

Live patching support

Access source packages for reference

You can view the source of packages you have installed on your instance for reference purposes by using tools provided in Amazon Linux. Source packages are available for all of the packages included in Amazon Linux and the online package repository. Simply determine the package name for the source package you want to install and use the yumdownloader --source command to view source within your running instance. For example:

[ec2-user ~]$ yumdownloader --source bash

The source RPM can be unpacked, and, for reference, you can view the source tree using standard RPM tools. After you finish debugging, the package is available for use.

cloud-init

The cloud-init package is an open-source application built by Canonical that is used to bootstrap Linux images in a cloud computing environment, such as Amazon EC2. Amazon Linux contains a customized version of cloud-init. It enables you to specify actions that should happen to your instance at boot time. You can pass desired actions to cloud-init through the user data fields when launching an instance. This means you can use common AMIs for many use cases and configure them dynamically at startup. Amazon Linux also uses cloud-init to perform initial configuration of the ec2-user account.

For more information, see the cloud-init documentation.

Amazon Linux uses the cloud-init actions found in /etc/cloud/cloud.cfg.d and /etc/cloud/cloud.cfg. You can create your own cloud-init action files in /etc/cloud/cloud.cfg.d. All files in this directory are read by cloud-init. They are read in lexical order, and later files overwrite values in earlier files.

The cloud-init package performs these (and other) common configuration tasks for instances at boot:

Supported user-data formats

The cloud-init package supports user-data handling of a variety of formats:

Subscribe to Amazon Linux notifications

To be notified when new AMIs are released, you can subscribe using Amazon SNS.

Whenever AMIs are released, we send notifications to the subscribers of the corresponding topic. To stop receiving these notifications, use the following procedure to unsubscribe.

Amazon Linux AMI SNS message format

The schema for the SNS message is as follows.

{
    "description": "Validates output from AMI Release SNS message",
    "type": "object",
    "properties": {
        "v1": {
            "type": "object",
            "properties": {
                "ReleaseVersion": {
                    "description": "Major release (ex. 2018.03)",
                    "type": "string"
                },
                "ImageVersion": {
                    "description": "Full release (ex. 2018.03.0.20180412)",
                    "type": "string"
                },
                "ReleaseNotes": {
                    "description": "Human-readable string with extra information",
                    "type": "string"
                },
                "Regions": {
                    "type": "object",
                    "description": "Each key will be a region name (ex. us-east-1)",
                    "additionalProperties": {
                        "type": "array",
                        "items": {
                            "type": "object",
                            "properties": {
                                "Name": {
                                    "description": "AMI Name (ex. amzn-ami-hvm-2018.03.0.20180412-x86_64-gp2)",
                                    "type": "string"
                                },
                                "ImageId": {
                                    "description": "AMI Name (ex.ami-467ca739)",
                                    "type": "string"
                                }
                            },
                            "required": [
                                "Name",
                                "ImageId"
                            ]
                        }
                    }
                }
            },
            "required": [
                "ReleaseVersion",
                "ImageVersion",
                "ReleaseNotes",
                "Regions"
            ]
        }
    },
    "required": [
        "v1"
    ]
}