As you may be aware, SQL Server container images are published and available on the Microsoft Artifact Registry (aka MCR or Microsoft Container Registry). To know more, please see Overview of SQL Server on Linux - SQL Server | Microsoft Docs. When you look at the complete tag listing for both RHEL-based and Ubuntu-based container images, you'll notice that SQL Server container images are published for all supported distributions for both RHEL (Red Hat Enterprise Linux) and Ubuntu.
To make this approach scalable & manageable, we will publish SQL Server container images to MCR based on the distribution's most recent version, rather than publishing it for all versions of both RHEL and Ubuntu. Here's an example to help you understand:
SQL Server 2017 supports Ubuntu 18.04 as the most recent distribution; thus, going forward SQL Server 2017 container images based on the Ubuntu 18.04 image will only be published to MCR and we will not publish the SQL Server 2017 container images for Ubuntu 16.04.
This policy will apply for all versions of SQL Server container images. Example:
SQL Server container images for 2019 and later will be available only for the most recent distribution, which is currently RHEL 8 and Ubuntu 20.04. When SQL Server supports RHEL 9 and Ubuntu 22.04, we'll start publishing SQL Server container images for those distributions and stop publishing images for older distributions to MCR.
On a side note, Ubuntu 16.04 has already transitioned to Extended Security Maintenance (ESM) support phase at the end of April 2021. Thus, the support for SQL Server on Ubuntu 16.04 is also limited as documented here Release notes for SQL Server 2019 on Linux - SQL Server | Microsoft Docs. You can also read more about ESM here: Ubuntu 16.04 LTS transitions to Extended Security Maintenance (ESM) | Ubuntu.
While we only publish SQL Server container images to MCR for the most recent versions of RHEL and Ubuntu distributions, SQL Server container images will be supported on all distributions listed here for SQL Server 2017, SQL Server 2019 & SQL Server 2022 (Preview), which means you can create your own custom SQL Server container image if you want to create a SQL Server container image for an older supported distribution. One such example is provided for reference here: mssql-docker/linux/preview/SLES at master · microsoft/mssql-docker (github.com). The already published SQL Server container images available on MCR will remain unchanged and will continue to exist. This change is only applicable to the upcoming SQL Server container images.
To know more about supportability aspect for custom SQL Server container images please refer: Support policy for SQL Server - SQL Server | Microsoft Docs.
