Container-Optimized OS from Google is an operating system image for your Compute Engine VMs that is optimized for running Docker containers. Container-Optimized OS is maintained by Google and based on the open source Chromium OS project. With Container-Optimized OS, you can bring up your Docker containers on Google Cloud Platform quickly, efficiently, and securely.
Features and Benefits
Container-Optimized OS provides the following benefits:
- Run Containers Out of the Box: Container-Optimized OS instances come
pre-installed with the Docker runtime and
cloud-init. With a Container-Optimized OS instance, you can bring up your Docker container at the same time you create your VM, with no on-host setup required. - Smaller attack surface: Container-Optimized OS has a smaller footprint, reducing your instance's potential attack surface.
- Locked-down by default: Container-Optimized OS instances include a locked-down firewall and other security settings by default.
- Automatic Updates: Container-Optimized OS instances are configured to automatically download weekly updates in the background; only a reboot is necessary to use the latest updates.
Limitations
Container-Optimized OS has limited or no support for some of the common features you may be familiar with on other operating systems:
- Container-Optimized OS does not include a package manager; as such, you'll be unable to install software packages directly on an instance. However, you can use CoreOS toolbox to install and run debugging and admin tools in an isolated container.
- Container-Optimized OS does not support execution of non-containerized applications.
- The Container-Optimized OS kernel is locked down; you'll be unable to install third-party kernel modules or drivers.
- Container-Optimized OS is not supported outside of the Google Cloud Platform environment.
Using Container-Optimized OS
Container-Optimized OS is the default node OS Image in Kubernetes Engine and other Kubernetes deployments on Google Cloud Platform. See the Kubernetes Engine Quickstart for more information on using Container-Optimized OS with Kubernetes Engine.
You can also use Container-Optimized OS to quickly bring up a Docker container on a Compute Engine instance with minimal setup. For more information, see Creating and Configuring Instances.
You can run tools like ping, the gcloud command-line tool, pstree, htop,
emacs and more using the CoreOS toolbox utility, which is pre-installed in
Container-Optimized OS at /usr/bin/toolbox. See Debugging with toolbox for
more information.
Use cases for Container-Optimized OS
Container-Optimized OS can be used to run most Docker containers. You should consider using Container-Optimized OS as the operating system for your Compute Engine instance if you have the following needs:
- You need support for Docker containers or Kubernetes with minimal setup.
- You need an operating system that has a small footprint and is security hardened for containers.
- You need an operating system that is tested and verified for running Kubernetes on your Compute Engine instances.
Container-Optimized OS may not be the right choice for you in the following cases:
- Your application is not containerized or your containerized application depends on kernel modules, drivers and other additional packages that are not available in Container-Optimized OS.
- You need professional customer support from a Linux provider (Canonical, Core OS, Redhat, SUSE, etc).
- You want your image and OS application to be fully supported outside Google Cloud Platform.
See Containers on GCP to learn about other operating systems you can use to run containerized applications on Google Cloud Platform. Compute Engine provides images for other popular operating systems, including images that are optimized for containers.