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This page provides details on Container-Optimized OS source code, including
how to access Container-Optimized OS image source, source for related
container tools, and how to build from source.
Container-Optimized OS image source
Container-Optimized OS from Google is a fork of theChromium OSopen-source project. You can
find the majority of the source code for Container-Optimized OS
in the COS repositorieshttps://cos.googlesource.com.
Some of the useful resources that can help you determine the
source code used to build the image include:
Inside the OS image, the/opt/google/chrome/resources/about_os_credits.htmlfile contains version and license information for all the packages used
to build that image.
Additional image artifacts, including archivedkernel sourcesandkernel headers,
are also available in a public Google Cloud Storage bucket undergs://cos-tools/<build-number>/.
For example, artifacts forcos-dev-105-17228-0-0are undergs://cos-tools/17228.0.0/.
Image artifacts for Arm-based images are available in the public
Cloud Storage bucket undergs://cos-tools/<build-number>/lakitu-arm64/.
For example, artifacts forcos-arm64-dev-105-17228-0-0are undergs://cos-tools/17228.0.0/lakitu-arm64/.
Actual source code archives for individual packages can also be found under
one of the package mirrors maintained by Chromium OS build system. You can
access them by appending the correct tarball name to one of the following URLs:
For example, to download kubernetes version 1.19.2, usehttps://storage.googleapis.com/chromeos-localmirror/distfiles/kubernetes-server-linux-amd64-1.19.2.tar.gz.
Container-Optimized OS from Google ships with some tools that download containers at runtime.
Those containers are also open sourced. The following table lists the
containers, their source location and release location.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eContainer-Optimized OS is a fork of the Chromium OS project, with its primary source code located in the COS repositories at \u003ccode\u003ehttps://cos.googlesource.com\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eDetailed version and license information for all packages used in a specific OS image can be found in the \u003ccode\u003e/opt/google/chrome/resources/about_os_credits.html\u003c/code\u003e file within that image.\u003c/p\u003e\n"],["\u003cp\u003eKernel source code, along with archived kernel sources and headers, is accessible via \u003ccode\u003ehttps://cos.googlesource.com/third_party/kernel/+/cos-5.15\u003c/code\u003e and in a public Google Cloud Storage bucket under \u003ccode\u003egs://cos-tools/<build-number>/\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eSeveral container tools that run on Container-Optimized OS are open-sourced, such as Toolbox and Cos-gpu-installer, with their source and release locations documented on this page.\u003c/p\u003e\n"],["\u003cp\u003eInstructions on how to build a Container-Optimized OS disk image from source are provided in the "Building from Open Source" documentation, linked on this page.\u003c/p\u003e\n"]]],[],null,["# Access source code\n\nThis page provides details on Container-Optimized OS source code, including\nhow to access Container-Optimized OS image source, source for related\ncontainer tools, and how to build from source.\n\nContainer-Optimized OS image source\n-----------------------------------\n\nContainer-Optimized OS from Google is a fork of the\n[Chromium OS](https://www.chromium.org/chromium-os) open-source project. You can\nfind the majority of the source code for Container-Optimized OS\nin the COS repositories\n\u003chttps://cos.googlesource.com\u003e.\n\nSome of the useful resources that can help you determine the\nsource code used to build the image include:\n\n- Inside the OS image, the `/opt/google/chrome/resources/about_os_credits.html`\n file contains version and license information for all the packages used\n to build that image.\n\n- Kernel source: \u003chttps://cos.googlesource.com/third_party/kernel/+/cos-5.15\u003e. \n\n Kernel config (x86): \u003chttps://cos.googlesource.com/third_party/kernel/+/refs/heads/cos-5.15/arch/x86/configs/lakitu_defconfig\u003e. \n\n Kernel config (Arm): \u003chttps://cos.googlesource.com/third_party/kernel/+/refs/heads/cos-5.15/arch/arm64/configs/lakitu_defconfig\u003e. \n\n The commit SHA1 of the kernel source used to build a particular version is\n also provided in the [release-notes](/container-optimized-os/docs/resources/release-notes) for that version.\n\n- Additional image artifacts, including archived **kernel sources** and **kernel headers** ,\n are also available in a public Google Cloud Storage bucket under\n `gs://cos-tools/\u003cbuild-number\u003e/`.\n For example, artifacts for `cos-dev-105-17228-0-0` are under `gs://cos-tools/17228.0.0/`.\n\n gcloud storage ls gs://cos-tools/17228.0.0/\n gs://cos-tools/17228.0.0/about_os_credits.html\n gs://cos-tools/17228.0.0/about_os_credits.html.md5\n gs://cos-tools/17228.0.0/cos-package-info.json\n gs://cos-tools/17228.0.0/cos-package-info.json.md5\n gs://cos-tools/17228.0.0/cos_full_payload_dev.bin\n gs://cos-tools/17228.0.0/gpu_R470_version\n gs://cos-tools/17228.0.0/gpu_R470_version.md5\n gs://cos-tools/17228.0.0/gpu_default_version\n gs://cos-tools/17228.0.0/gpu_default_version.md5\n gs://cos-tools/17228.0.0/gpu_latest_version\n gs://cos-tools/17228.0.0/gpu_latest_version.md5\n gs://cos-tools/17228.0.0/kernel-headers.tgz\n gs://cos-tools/17228.0.0/kernel-headers.tgz.md5\n gs://cos-tools/17228.0.0/kernel-src.tar.gz\n gs://cos-tools/17228.0.0/kernel-src.tar.gz.md5\n gs://cos-tools/17228.0.0/kernel_commit\n gs://cos-tools/17228.0.0/kernel_commit.md5\n gs://cos-tools/17228.0.0/kernel_info\n gs://cos-tools/17228.0.0/kernel_info.md5\n gs://cos-tools/17228.0.0/manifest.xml\n gs://cos-tools/17228.0.0/manifest.xml.md5\n gs://cos-tools/17228.0.0/toolchain.tar.xz\n gs://cos-tools/17228.0.0/toolchain.tar.xz.gcs\n gs://cos-tools/17228.0.0/toolchain.tar.xz.md5\n gs://cos-tools/17228.0.0/toolchain_env\n gs://cos-tools/17228.0.0/toolchain_env.md5\n gs://cos-tools/17228.0.0/vmlinux\n gs://cos-tools/17228.0.0/vmlinux.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/\n gs://cos-tools/17228.0.0/lakitu/\n\n- Image artifacts for Arm-based images are available in the public Cloud Storage bucket under `gs://cos-tools/\u003cbuild-number\u003e/lakitu-arm64/`. For example, artifacts for `cos-arm64-dev-105-17228-0-0` are under `gs://cos-tools/17228.0.0/lakitu-arm64/`.\n\n gcloud storage ls gs://cos-tools/17228.0.0/lakitu-arm64/\n gs://cos-tools/17228.0.0/lakitu-arm64/about_os_credits.html\n gs://cos-tools/17228.0.0/lakitu-arm64/about_os_credits.html.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/cos-package-info.json\n gs://cos-tools/17228.0.0/lakitu-arm64/cos-package-info.json.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/gpu_R470_version\n gs://cos-tools/17228.0.0/lakitu-arm64/gpu_R470_version.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/gpu_default_version\n gs://cos-tools/17228.0.0/lakitu-arm64/gpu_default_version.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/gpu_latest_version\n gs://cos-tools/17228.0.0/lakitu-arm64/gpu_latest_version.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/kernel-headers.tgz\n gs://cos-tools/17228.0.0/lakitu-arm64/kernel-headers.tgz.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/kernel-src.tar.gz\n gs://cos-tools/17228.0.0/lakitu-arm64/kernel-src.tar.gz.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/kernel_commit\n gs://cos-tools/17228.0.0/lakitu-arm64/kernel_commit.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/kernel_info\n gs://cos-tools/17228.0.0/lakitu-arm64/kernel_info.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/manifest.xml\n gs://cos-tools/17228.0.0/lakitu-arm64/manifest.xml.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/toolchain.tar.xz\n gs://cos-tools/17228.0.0/lakitu-arm64/toolchain.tar.xz.gcs\n gs://cos-tools/17228.0.0/lakitu-arm64/toolchain.tar.xz.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/toolchain_env\n gs://cos-tools/17228.0.0/lakitu-arm64/toolchain_env.md5\n gs://cos-tools/17228.0.0/lakitu-arm64/vmlinux\n gs://cos-tools/17228.0.0/lakitu-arm64/vmlinux.md5\n\n- Those familiar with Chromium OS build system may also find the build recipes under\n \u003chttps://cos.googlesource.com/cos/overlays/board-overlays/+/master/project-lakitu/\u003e\n useful.\n\n- Actual source code archives for individual packages can also be found under\n one of the package mirrors maintained by Chromium OS build system. You can\n access them by appending the correct tarball name to one of the following URLs:\n\n - `https://storage.googleapis.com/chromeos-mirror/gentoo/distfiles/`\n - `https://storage.googleapis.com/chromeos-localmirror/distfiles/`\n\n For example, to download kubernetes version 1.19.2, use\n `https://storage.googleapis.com/chromeos-localmirror/distfiles/kubernetes-server-linux-amd64-1.19.2.tar.gz`.\n\nThe\n[Chromium OS Build FAQ](http://www.chromium.org/chromium-os/how-tos-and-troubleshooting/portage-build-faq)\nand other [Chromium OS Build](http://www.chromium.org/chromium-os/build) documentation\nexplains how the build system and package mirrors work.\n\nContainer source\n----------------\n\nContainer-Optimized OS from Google ships with some tools that download containers at runtime.\nThose containers are also open sourced. The following table lists the\ncontainers, their source location and release location.\n\nBuilding from source\n--------------------\n\nFollow the instructions on [Building from Open Source](/container-optimized-os/docs/how-to/building-from-open-source)\nto build a Container-Optimized OS disk image from the source.\n\nSource code contributions\n-------------------------\n\nContainer-Optimized OS does not accept direct contributions from the public."]]
