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
Release support duration
A major version on Container-Optimized OS corresponds to a new
as explained in
After becoming stable, most Release Milestones (or major versions) are actively
supported for approximately 6 weeks. During these 6 weeks, the release
milestone will get critical bug fixes and security updates.
Roughly twice each year, the Container-Optimized OS team will release a long
term support (LTS) milestone. After becoming stable, LTS milestones are actively
supported for approximately 15 months. LTS milestones follow the usual
development cycle that is described in Release channels,
meaning that they still go through the
channels. However, once a LTS milestone becomes
stable, it will continue to
receive security updates and critical bug fixes for approximately 15 months,
as opposed to 6 weeks for a typical milestone.
At the end of a milestone's support window, the release milestone is deprecated.
Specifically, we set the
DEPRECATED flag on images in
that milestone and those images stop showing in the active list of images in
Images in a deprecated milestone are still usable, but issues with those images
will only be fixed in newer milestones. Users may see a warning if they are
gcloud command-line tool while accessing deprecated images.
Users must upgrade to one of the newer active milestones to continue to have easy access to bug fixes and security patches.
Every major release milestone goes through
(also described in detail in
These correspond to
cos-stable image families in the
You can identify the stage a release is at by looking at the image name
cos-stable-54-8743-71-0) or by looking at the image family it
belongs to (example:
cos-stable) as listed by
gcloud compute images list
--project=cos-cloud --no-standard-images command.
Once a LTS milestone becomes stable, a corresponding image family is added to
cos-cloud project (example:
cos-69-lts). This family can be used
to identify the latest image on a specific LTS milestone.
Users can always expect to see at least 1 image in the
Release milestone progression
Progression for normal milestones is visualized in the following diagram.
LTS milestones follow a similar schedule. LTS milestones are only different in that they are stable for a much longer period of time.
Please refer to
for a detailed explanation of each of the
Each stage receives varying degrees of attention with respect to our support
policy. This is explained below.
|Image Family||Duration (Soak Period)||Release Frequency||Properties|