cri-o

module
Version: v1.25.1 Latest Latest
Warning

This package is not in the latest version of its module.

Go to latest
Published: Oct 7, 2022 License: Apache-2.0

README

CRI-O logo

CRI-O - OCI-based implementation of Kubernetes Container Runtime Interface

Stable Status codecov Release Notes Dependencies GoDoc CII Best Practices Go Report Card FOSSA Status Mentioned in Awesome CRI-O Gitpod ready-to-code

Compatibility matrix: CRI-O ⬄ Kubernetes

CRI-O follows the Kubernetes release cycles with respect to its minor versions (1.x.0). Patch releases (1.x.y) for CRI-O are not in sync with those from Kubernetes, because those are scheduled for each month, whereas CRI-O provides them only if necessary. If a Kubernetes release goes End of Life, then the corresponding CRI-O version can be considered in the same way.

This means that CRI-O also follows the Kubernetes n-2 release version skew policy when it comes to feature graduation, deprecation or removal. This also applies to features which are independent from Kubernetes.

For more information visit the Kubernetes Version Skew Policy.

Version - Branch Kubernetes branch/version Maintenance status
CRI-O HEAD - main Kubernetes master branch
CRI-O 1.24.x - release-1.24 Kubernetes 1.24 branch, v1.24.x =
CRI-O 1.23.x - release-1.23 Kubernetes 1.23 branch, v1.23.x =
CRI-O 1.22.x - release-1.22 Kubernetes 1.22 branch, v1.22.x =
CRI-O 1.21.x - release-1.21 Kubernetes 1.21 branch, v1.21.x =

Key:

  • Changes in the main Kubernetes repo about CRI are actively implemented in CRI-O
  • = Maintenance is manual, only bugs will be patched.

The release notes for CRI-O are hand-crafted and can be continuously retrieved from our GitHub pages website.

What is the scope of this project?

CRI-O is meant to provide an integration path between OCI conformant runtimes and the Kubelet. Specifically, it implements the Kubelet Container Runtime Interface (CRI) using OCI conformant runtimes. The scope of CRI-O is tied to the scope of the CRI.

At a high level, we expect the scope of CRI-O to be restricted to the following functionalities:

  • Support multiple image formats including the existing Docker image format
  • Support for multiple means to download images including trust & image verification
  • Container image management (managing image layers, overlay filesystems, etc)
  • Container process lifecycle management
  • Monitoring and logging required to satisfy the CRI
  • Resource isolation as required by the CRI

What is not in the scope of this project?

  • Building, signing and pushing images to various image storages
  • A CLI utility for interacting with CRI-O. Any CLIs built as part of this project are only meant for testing this project and there will be no guarantees on the backward compatibility with it.

This is an implementation of the Kubernetes Container Runtime Interface (CRI) that will allow Kubernetes to directly launch and manage Open Container Initiative (OCI) containers.

The plan is to use OCI projects and best of breed libraries for different aspects:

It is currently in active development in the Kubernetes community through the design proposal. Questions and issues should be raised in the Kubernetes sig-node Slack channel.

Commands

Command Description
crio(8) OCI Kubernetes Container Runtime daemon

Note that kpod and its container management and debugging commands have moved to a separate repository, located here.

Configuration

File Description
crio.conf(5) CRI-O Configuration file
policy.json(5) Signature Verification Policy File(s)
registries.conf(5) Registries Configuration file
storage.conf(5) Storage Configuration file

OCI Hooks Support

You can configure CRI-O to inject OCI Hooks when creating containers.

CRI-O Usage Transfer

We provide useful information for operations and development transfer as it relates to infrastructure that utilizes CRI-O.

Communication

For async communication and long running discussions please use issues and pull requests on the GitHub repo. This will be the best place to discuss design and implementation.

For chat communication, we have a channel on the Kubernetes slack that everyone is welcome to join and chat about development.

Awesome CRI-O

We maintain a curated list of links related to CRI-O. Did you find something interesting on the web about the project? Awesome, feel free to open up a PR and add it to the list.

Getting started

Installing CRI-O

To install CRI-O, you can follow our installation guide. Alternatively, if you'd rather build CRI-O from source, checkout our setup guide. We also provide a way in building static binaries of CRI-O via nix. Those binaries are available for every successfully built commit on our Google Cloud Storage Bucket. This means that the latest commit can be installed via our convenience script:

> curl https://raw.githubusercontent.com/cri-o/cri-o/main/scripts/get | bash

The script automatically verifies the uploaded sigstore signatures as well, if the local system has cosign available in its $PATH. The same applies to the SPDX based bill of materials (SBOM), which gets automatically verified if the bom tool is in $PATH.

Beside amd64 we also support the arm64 bit architecture. This can be selected via the script, too:

> curl https://raw.githubusercontent.com/cri-o/cri-o/main/scripts/get | bash -s -- -a arm64

It is also possible to select a specific git SHA or tag by:

> curl https://raw.githubusercontent.com/cri-o/cri-o/main/scripts/get | bash -s -- -t v1.21.0

The above script resolves to the download URL of the static binary bundle tarball matching the format:

https://storage.googleapis.com/cri-o/artifacts/cri-o.$ARCH.$REV.tar.gz

where $ARCH can be amd64 or arm64 and $REV can be any git SHA or tag. Please be aware that using the latest main SHA might cause a race, because the CI has not finished publishing the artifacts yet or failed.

We also provide a Software Bill of Materials (SBOM) in the SPDX format for each bundle. The SBOM is available at the same URL like the bundle itself, but suffixed with .spdx:

https://storage.googleapis.com/cri-o/artifacts/cri-o.$ARCH.$REV.tar.gz.spdx
Running Kubernetes with CRI-O

Before you begin, you'll need to start CRI-O

You can run a local version of Kubernetes with CRI-O using local-up-cluster.sh:

  1. Clone the Kubernetes repository
  2. From the Kubernetes project directory, run:
CGROUP_DRIVER=systemd \
CONTAINER_RUNTIME=remote \
CONTAINER_RUNTIME_ENDPOINT='unix:///var/run/crio/crio.sock' \
./hack/local-up-cluster.sh

For more guidance in running CRI-O, visit our tutorial page

The HTTP status API

CRI-O exposes per default the gRPC API to fulfill the Container Runtime Interface (CRI) of Kubernetes. Besides this, there exists an additional HTTP API to retrieve further runtime status information about CRI-O. Please be aware that this API is not considered to be stable and production use-cases should not rely on it.

On a running CRI-O instance, we can access the API via an HTTP transfer tool like curl:

$ sudo curl -v --unix-socket /var/run/crio/crio.sock http://localhost/info | jq
{
  "storage_driver": "btrfs",
  "storage_root": "/var/lib/containers/storage",
  "cgroup_driver": "systemd",
  "default_id_mappings": { ... }
}

The following API entry points are currently supported:

Path Content-Type Description
/info application/json General information about the runtime, like storage_driver and storage_root.
/containers/:id application/json Dedicated container information, like name, pid and image.
/config application/toml The complete TOML configuration (defaults to /etc/crio/crio.conf) used by CRI-O.
/pause/:id application/json Pause a running container.
/unpause/:id application/json Unpause a paused container.

The tool crio-status can be used to access the API with a dedicated command line tool. It supports all API endpoints via the dedicated subcommands config, info and containers, for example:

$ sudo go run cmd/crio-status/main.go info
cgroup driver: systemd
storage driver: btrfs
storage root: /var/lib/containers/storage
default GID mappings (format <container>:<host>:<size>):
  0:0:4294967295
default UID mappings (format <container>:<host>:<size>):
  0:0:4294967295
Metrics

Please refer to the CRI-O Metrics guide.

Container Runtime Interface special cases

Some aspects of the Container Runtime are worth some additional explanation. These details are summarized in a dedicated guide.

Debugging tips

Having an issue? There are some tips and tricks for debugging located in our debugging guide

Adopters

An incomplete list of adopters of CRI-O in production environments can be found here. If you're a user, please help us complete it by submitting a pull-request!

Weekly Meeting

A weekly meeting is held to discuss CRI-O development. It is open to everyone. The details to join the meeting are on the wiki.

Governance

For more information on how CRI-O is goverened, take a look at the governance file

License Scan

FOSSA Status

Directories

Path Synopsis
cmd
contrib
pkg
scripts
release-branch-forward
This tools automatically finds the latest CRI-O release branch and merges the latest main branch into it.
This tools automatically finds the latest CRI-O release branch and merges the latest main branch into it.
useragent
Package useragent provides helper functions to pack version information into a single User-Agent header.
Package useragent provides helper functions to pack version information into a single User-Agent header.
test
mocks/cmdrunner
Package cmdrunnermock is a generated GoMock package.
Package cmdrunnermock is a generated GoMock package.
mocks/containers/image/v5
Package imagetypesmock is a generated GoMock package.
Package imagetypesmock is a generated GoMock package.
mocks/containerstorage
Package containerstoragemock is a generated GoMock package.
Package containerstoragemock is a generated GoMock package.
mocks/criostorage
Package criostoragemock is a generated GoMock package.
Package criostoragemock is a generated GoMock package.
mocks/lib
Package libconfigmock is a generated GoMock package.
Package libconfigmock is a generated GoMock package.
mocks/oci
Package ocimock is a generated GoMock package.
Package ocimock is a generated GoMock package.
mocks/ocicni
Package ocicnitypesmock is a generated GoMock package.
Package ocicnitypesmock is a generated GoMock package.
errdefs
Package errdefs defines the common errors used throughout containerd packages.
Package errdefs defines the common errors used throughout containerd packages.
internal
dbusmgr
Code in this package is heavily adapted from https://github.com/opencontainers/runc/blob/7362fa2d282feffb9b19911150e01e390a23899d/libcontainer/cgroups/systemd Credit goes to the runc authors.
Code in this package is heavily adapted from https://github.com/opencontainers/runc/blob/7362fa2d282feffb9b19911150e01e390a23899d/libcontainer/cgroups/systemd Credit goes to the runc authors.
lib
log
Package log provides a global interface to logging functionality
Package log provides a global interface to logging functionality
oci
registrar
Package registrar provides name registration.
Package registrar provides name registration.
storage
Package storage provides helper functions for creating and managing CRI pod sandboxes and containers and metadata associated with them in the format that crio understands.
Package storage provides helper functions for creating and managing CRI pod sandboxes and containers and metadata associated with them in the format that crio understands.

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
y or Y : Canonical URL