Support policy

Container-Optimized OS is tested and qualified for running various container workloads on Google Cloud. It is actively patched with security updates (CVEs) and bug-fixes to address issues that impact Google Cloud users. Users get access to these fixes via our image releases in the cos-cloud project.

Container-Optimized OS image support is available for our Long Term Supported (LTS) family of images in the cos-cloud project. For a description of available image families, see Versioning scheme. The following support commitment applies only to our LTS family of images.

Support duration

Approximately twice each year, the Container-Optimized OS team releases a Long Term Supported (LTS) milestone on its cos-[MILESTONE]-lts and cos-arm64-[MILESTONE]-lts image families. Once a milestone is introduced on the LTS families, it is supported for 2 years.

During this support window:

  • The milestone is actively patched for any critical bugs.
  • The milestone is actively scanned for security vulnerabilities, and security fixes are applied on regular basis.
  • New releases containing high priority bug and security fixes are released on-demand.
  • New releases containing medium and low priority bug and security fixes are released every 3 months.
  • To maintain stability, no new breaking features are introduced.
  • All changes in the image are documented on a dedicated release notes page.


At the end of a milestone's support window, the corresponding cos-[MILESTONE]-lts and cos-arm64-[MILESTONE]-lts families are deprecated. Specifically, we set the DEPRECATED flag on images in that milestone and those images stop appearing in the active list of images in the cos-cloud project.

Deprecated images are still accessible and usable when accessed directly by name using the images get API. However, any issues with those images might not be fixed or will only be fixed in newer milestones. Issues reported against deprecated images may be fixed only in newer image milestones. To continue having access to bug fixes and security patches, upgrade to one of the newer active milestones.

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