Comparing Amazon Linux 2 and Amazon Linux 2023

The following topics outline key differences between Amazon Linux 2 (AL2) and Amazon Linux 2023 (AL2023).

Added, upgraded, and removed packages

AL2023 contains thousands of software packages available for use. For a full list of all packages added, upgraded, or removed in AL2023 when compared to prior Amazon Linux versions, see Package changes in AL2023.

To request a package to be added or changed in AL2023, you can do so by filing an issue in the amazon-linux-2023 repo on GitHub.

Support for each release

For AL2023, we offer five years of support.

For more information, see Release cadence.

Naming and versioning changes

AL2023 supports the same mechanisms that AL2 supports for platform identification. AL2023 also introduces new files for platform identification.

For more information, see Naming and versioning.

Optimizations

AL2023 optimizes boot time to reduce the time from instance launch to running the customer workload. These optimizations span the Amazon EC2 instance kernel configuration, cloud-init configurations, and features that are built into packages in the OS such askmod and systemd.

For more information about optimizations, see Performance and operational optimizations.

Python 2.7 has been replaced with Python 3

AL2 provides support and security patches for Python 2.7 until June 2025, as part of our long-term support (LTS) commitment for AL2 core packages. This support extends beyond the upstream Python community declaration of Python 2.7 end-of-life of January 2020.

Amazon Linux 2 uses the yum package manager, which has a hard dependency on Python 2.7. In AL2023 the dnf package manager has migrated to Python 3, and no longer requires Python 2.7. AL2023 has completely moved to Python 3.

For more information on Python on Amazon Linux, see Python in AL2023.

Security updates

SELinux

By default, Security Enhanced Linux (SELinux) for AL2023 is enabled and set to permissive mode. In permissive mode, permission denials are logged but not enforced.

SELinux is a security feature of the Amazon Linux kernel, which was disabled in AL2. SELinux is a collection of kernel features and utilities that provides mandatory access control (MAC) architecture into the major subsystems of the kernel.

For more information, see Setting SELinux modes.

For more information about SELinux repositories, tools, and policies, see SELinux Notebook, Types of SELinux policy, and SELinux Project .

OpenSSL 3

AL2023 features the Open Secure Sockets Layer version 3 (OpenSSL 3) cryptography toolkit. AL2023 supports TLS 1.3 and TLS 1.2 network protocols.

By default, AL2 comes with OpenSSL 1.0.2. You can build applications against OpenSSL 1.1.1.

For more information about OpenSSL, see the OpenSSL migration guide.

For more information about security, see Security updates and features.

IMDSv2

By default, any instances launched with the AL2023 AMI will require the use of IMDSv2-only and your default hop limit will be set to 2 to allow for containerized workload support. This is done by setting the imds-support parameter to v2.0. For more information, see Configure the AMI in the Amazon EC2 User Guide for Linux Instances.

You can still manually override these settings and enable IMDSv1 using Instance Metadata option launch properties. You can also still use IAM controls to enforce different IMDS settings. For more information about setting up and using the Instance Metadata Service, see Use IMDSv2, Configure instance metadata options for new instances, and Modify instance metadata options for existing instances, in the Amazon EC2 User Guide for Linux Instances.

Removal of log4j hotpatch (log4j-cve-2021-44228-hotpatch)

In response to CVE-2021-44228, Amazon Linux released an RPM packaged version of the Hotpatch for Apache Log4j for Amazon Linux 1 (AL1) and AL2. In the announcement of the addition of the hotpatch to Amazon Linux we noted that "Installing the hotpatch is not a replacement for updating to a log4j version that mitigates CVE-2021-44228 or CVE-2021-45046.".

The hotpatch was a mitigation to allow time to patch log4j. The first General Availability (GA) release of AL2023 was 15 months after CVE-2021-44228, thus AL2023 doesn't ship with the hotpatch (enabled or not).

Customers running their own log4j versions on Amazon Linux are advised to ensure they have updated to versions not affected by CVE-2021-44228 or CVE-2021-45046.

AL2023 provides guidance on Updating Amazon Linux 2023 so that you can keep up to date with security patches. Security advisories are published on the Amazon Linux Security Center.

Deterministic upgrades for stability

With the deterministic upgrades through versioned repositories feature, every AL2023 Amazon Machine Image (AMI) by default is locked to a specific repository version. You can use deterministic upgrades to achieve greater consistency among package versions and updates. Each release, major or minor, includes a specific repository version.

New with AL2023, deterministic upgrading by default is enabled. This is an improvement over the manual, incremental method of locking that's used in AL2 and other earlier versions.

For more information, see Using Deterministic upgrades through versioned repository.

Sourced from multiple upstreams

AL2023 is RPM-based and includes components sourced from multiple versions of Fedora and other distributions, such as CentOS 9 Stream. The Amazon Linux kernel is sourced from the long-term support (LTS) releases directly from kernel.org, chosen independently from other distributions.

For more information, see Relationship to Fedora.

AMI root file system and default Amazon EBS volume type

The AL2023 AMI and AL2 both use the XFS file system on the root file system. For AL2023, the mkfsoptions for the root device file system are further optimized for Amazon EC2. AL2023 also supports a number of other file systems that you can use on other volumes to meet your specific requirements.

AL2023 AMIs use Amazon EBS gp3 volumes by default, whereas AL2 AMIs use Amazon EBS gp2 volumes by default. You can change the volume type when you launch an instance. For more information about Amazon EBS volume types, see Amazon EBS General Purpose Volumes. For more information about launching an Amazon EC2 instance, see Launch an instance in the Amazon EC2 User Guide for Linux Instances.

Networking system service

The systemd-networkd system service manages the network interfaces in AL2023. This is a change from AL2, which uses ISC dhclient or dhclient.

For more information, see Networking service.

Unified Control Group hierarchy (cgroup v2)

A Control Group (cgroup) is a Linux kernel feature to hierarchically organize processes and distribute system resources between them. Control Groups are used extensively to implement a container runtime, and by systemd.

Amazon Linux 2 supports cgroupv1, and Amazon Linux 2023 supports cgroupv2. This is notable if running containerized workloads, such as when Using Amazon Linux 2023 based Linux instances for Amazon ECS capacity.

While AL2023 still includes code that can make the system run using cgroupv1, this is not a recommended or supported configuration, and will be completely removed in a future major release of Amazon Linux.

There is extensive documentation regarding the low-level Linux Kernel interfaces, as well as systemd cgroup delegation documentation.

A common use case outside of containers is for creating systemd units which have limits placed on the system resources they can use. See the systemd.resource-control documentation for details.

Task scheduling

The cronie package was installed by default on the AL2 AMI, providing support for the traditional crontab way of scheduling periodic tasks. In AL2023, cronie is not included by default. Therefore, support for crontab is no longer provided by default.

You can optionally install the cronie package to use classic cron jobs. We recommend that you migrate to systemd timers due to the added functionality provided by systemd.

Packages for glibc, gcc, and binutils

AL2023 includes many of the same core packages as AL2.

We updated the following three core toolchain packages for AL2023.

For more information, see Core toolchain packages glibc, gcc, binutils.

Package manager

The default software package management tool on AL2023 is DNF. DNF is the successor to YUM, the package management tool in AL2.

For more information, see Package management tool.

Logging system

In AL2023 the logging system package has changed from AL2. AL2023 doesn't install rsyslog by default, so the text based log files such as /var/log/messages that were available in AL2 aren't available by default. The default configuration for AL2023 is systemd-journal, which can be examined using journalctl. Although rsyslog is an optional package in AL2023, we recommend the new systemd based journalctl interface and related packages. For more information, see the journalctl manual page.

Package changes for curl and libcurl

AL2023 separates out the common protocols and functionality of the curl and libcurl packages into curl-minimal and libcurl-minimal. This reduces the disk, memory, and dependency footprint for most users, and is the default package for AL2023 AMIs and containers.

If the full functionality of curl is required, for example for gopher:// support, run the following commands to install the curl-full and libcurl-full packages.

$ dnf swap libcurl-minimal libcurl-full

$ dnf swap curl-minimal curl-full

GNU Privacy Guard (GNUPG)

AL2023 separates out minimal and complete functionality for the gnupg2 package into gnupg2-minimal and gnupg2-full packages. By default, only the gnupg2-minimal package is installed. This provides the minimal functionality required to verify the digital signatures on rpm packages.

For more functionality from gnupg2, such as the ability to download keys from a key server, ensure that the gnupg2-full package is installed. Run the following command to swap gnupg2-minimal for gnupg2-full.

$ dnf swap gnupg2-minimal gnupg2-full

Amazon Corretto as the default JVM

AL2023 ships with Amazon Corretto as the default (and only) Java Development Kit (JDK). For Java based packages in AL2023, these are all built with Amazon Corretto 17.

Users coming from AL2 will be able to smoothly transition from the equivalent OpenJDK version on AL2 over to Amazon Corretto.

AWS CLI v2

AL2023 ships with AWS CLI version 2, while AL2 continues to ship with version 1 of the AWS CLI.

UEFI Preferred

By default, any instances launched with the AL2023 AMI on instance types that support UEFI firmware will launch in UEFI mode. This is done by setting the Boot Mode AMI parameter to uefi-preferred. For more information, see Boot Modes in the Amazon EC2 User Guide for Linux Instances.

SSH server default configuration changes

For the AL2023 AMI, we changed the types of sshd host keys that we generate with the release. We also dropped some legacy key types to avoid generating them at launch time. Clients must support the rsa-sha2-256 and rsa-sha2-512 protocols or ssh-ed25519 with use of an ed25519 key. By default, ssh-rsa signatures are disabled.

Additionally, AL2023 configuration settings in the default sshd_config file contain UseDNS=no. This new setting means that DNS impairments are less likely to block your ability to establish ssh sessions with your instances. The tradeoff is that the "from=hostname.domain,hostname.domain" line entries in your authorized_keys files won't be resolved. Because sshd no longer attempts to resolve the DNS names, each comma separated hostname.domain value must be translated to a corresponding IP address.

For more information, see Default SSH server configuration.

Extra Packages for Enterprise Linux (EPEL)

Extra Packages for Enterprise Linux (EPEL) is a project in the Fedora community with the objective of creating a large array of packages for enterprise-level Linux operating systems. The project has primarily produced RHEL and CentOS packages. AL2 features a high level of compatibility with CentOS 7. As a result, many EPEL7 packages work on AL2. However, AL2023 doesn't support EPEL or EPEL-like repositories.

Using cloud-init

In AL2023, cloud-init manages the package repository. By default, in earlier versions of Amazon Linux, cloud-init installed security updates. This isn't the default for AL2023. The new deterministic upgrading features for updating releasever at launch describe the AL2023 way to enable package updates at launch. For more information, see Managing packages and operating system updates and Deterministic upgrades for stability.

With AL2023, you can use cloud-init with SELinux. For more information, see Use cloud-init to enable enforcing mode.

Cloud-init loads configuration content with cloud-init from remote locations using HTTP(S). In earlier versions, Amazon Linux doesn't alert you when remote resources are unavailable. In AL2023, unavailable remote resources creates a fatal error and fails the cloud-init execution. This change in behavior from AL2, provides a safer "fail closed" default behavior.

For more information, see Customized cloud-init and the cloud-init Documentation.

Graphical desktop support

AL2023 is cloud-centered and optimized for Amazon EC2 usage and currently does not include a graphical or desktop environment. To provide feedback on GitHub, see https://github.com/ .

Compiler Triplet

AL2023 sets the compiler triplet for GCC and LLVM to indicate that amazon is the vendor.

Thus, the AL2 aarch64-redhat-linux-gcc becomes aarch64-amazon-linux-gcc on AL2023.

This should be completely transparent for users, and only possibly affects those who are building compilers on AL2023.

32bit x86 (i686) Packages

As part of the 2014.09 release of Amazon Linux 1 (AL1) it was announced that it would be the last release to produce 32-bit AMIs. Thus, from the 2015.03 release of AL1, Amazon Linux no longer supported running the system in 32-bit mode. AL2 offered limited runtime support for 32bit binaries on x86-64 hosts, and did not provide development packages to enable the building of new 32-bit binaries. AL2023 no longer includes any 32bit userspace packages. Customers are advised that they need to complete their transition to 64-bit code.

If you need to run 32-bit binaries on AL2023, it is possible to use the 32-bit user-space from AL2 inside an AL2 container running on top of AL2023.

lsb_release and the system-lsb-core package

Historically, some software invoked the lsb_release command (provided in AL2 by the system-lsb-core package) to get information about the Linux distribution that it was being run on. The Linux Standards Base (LSB) introduced this command and Linux distributions adopted it. Linux distributions have evolved to use the simpler standard of holding this information in /etc/os-release and other related files.

The os-release standard comes out of systemd. For more information, see systemd os-release documentation.

AL2023 doesn't ship with the lsb_release command, and doesn't include the system-lsb-core package. Software should complete the transition to the os-release standard to maintain compatibility with Amazon Linux and other major Linux distributions.