196 lines
6.1 KiB
Markdown
196 lines
6.1 KiB
Markdown
# cri-o - OCI-based implementation of Kubernetes Container Runtime Interface
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[](https://travis-ci.org/kubernetes-incubator/cri-o)
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[](https://goreportcard.com/report/github.com/kubernetes-incubator/cri-o)
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### Status: pre-alpha
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## What is the scope of this project?
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cri-o is meant to provide an integration path between OCI conformant runtimes and the kubelet.
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Specifically, it implements the Kubelet Container Runtime Interface (CRI) using OCI conformant runtimes.
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The scope of cri-o is tied to the scope of the CRI.
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At a high level, we expect the scope of cri-o to be restricted to the following functionalities:
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* Support multiple image formats including the existing Docker image format
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* Support for multiple means to download images including trust & image verification
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* Container image management (managing image layers, overlay filesystems, etc)
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* Container process lifecycle management
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* Monitoring and logging required to satisfy the CRI
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* Resource isolation as required by the CRI
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## What is not in scope for this project?
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* Building, signing and pushing images to various image storages
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* 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 backwards compatibility with it.
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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.
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The plan is to use OCI projects and best of breed libraries for different aspects:
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- Runtime: [runc](https://github.com/opencontainers/runc) (or any OCI runtime-spec implementation) and [oci runtime tools](https://github.com/opencontainers/runtime-tools)
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- Images: Image management using [containers/image](https://github.com/containers/image)
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- Storage: Storage and management of image layers using [containers/storage](https://github.com/containers/storage)
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- Networking: Networking support through use of [CNI](https://github.com/containernetworking/cni)
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It is currently in active development in the Kubernetes community through the [design proposal](https://github.com/kubernetes/kubernetes/pull/26788). Questions and issues should be raised in the Kubernetes [sig-node Slack channel](https://kubernetes.slack.com/archives/sig-node).
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## Getting started
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### Prerequisites
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`runc` version 1.0.0.rc1 or greater is expected to be installed on the system. It is picked up as the default runtime by ocid.
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### Build
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`glib2-devel` and `glibc-static` packages on Fedora or ` libglib2.0-dev` on Ubuntu or equivalent is required.
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In order to enable seccomp support you will need to install `libseccomp` on your platform.
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> e.g. `libseccomp-devel` for CentOS/Fedora, or `libseccomp-dev` for Ubuntu
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```bash
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$ GOPATH=/path/to/gopath
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$ mkdir $GOPATH
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$ go get -d github.com/kubernetes-incubator/cri-o
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$ cd $GOPATH/src/github.com/kubernetes-incubator/cri-o
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$ make install.tools
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$ make
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$ sudo make install
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```
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Otherwise, if you do not want to build `cri-o` with seccomp support you can add `BUILDTAGS=""` when running make.
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```bash
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# create a 'github.com/kubernetes-incubator' in your $GOPATH/src
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cd github.com/kubernetes-incubator
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git clone https://github.com/kubernetes-incubator/cri-o
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cd cri-o
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make BUILDTAGS=""
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sudo make install
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```
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#### Build Tags
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`cri-o` supports optional build tags for compiling support of various features.
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To add build tags to the make option the `BUILDTAGS` variable must be set.
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```bash
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make BUILDTAGS='seccomp apparmor'
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```
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| Build Tag | Feature | Dependency |
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|-----------|------------------------------------|-------------|
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| seccomp | syscall filtering | libseccomp |
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| selinux | selinux process and mount labeling | <none> |
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| apparmor | apparmor profile support | libapparmor |
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### Running pods and containers
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#### Start the server
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```
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# ocid --debug
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```
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If the default `--runtime` value does not point to your runtime:
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```
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# ocid --runtime $(which runc)
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```
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#### Create a pod
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```
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$ ocic pod run --config test/testdata/sandbox_config.json
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```
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#### Get pod status
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```
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# ocic pod status --id <pod_id>
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```
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#### Run a container inside a pod
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```
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# ocic ctr create --pod <pod_id> --config test/testdata/container_redis.json
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```
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#### Start a container
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```
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# ocic ctr start --id <ctr_id>
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```
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#### Get container status
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```
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# ocic ctr status --id <ctr_id>
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```
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#### Stop a container
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```
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# ocic ctr stop --id <ctr_id>
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```
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#### Remove a container
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```
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# ocic ctr remove --id <ctr_id>
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```
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#### Stop a pod
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```
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# ocic pod stop --id <pod_id>
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```
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#### Remove a pod
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```
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# ocic pod remove --id <pod_id>
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```
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#### List pods
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```
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# ocic pod list
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```
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#### List containers
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```
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# ocic ctr list
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```
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### Setup CNI networking
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Follow the steps below in order to setup networking in your pods using the CNI
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bridge plugin. Nothing else is required after this since `CRI-O` automatically
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setup networking if it finds any CNI plugin.
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```sh
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$ go get -d github.com/containernetworking/cni
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$ cd $GOPATH/src/github.com/containernetworking/cni
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$ sudo mkdir -p /etc/cni/net.d
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$ sudo sh -c 'cat >/etc/cni/net.d/10-mynet.conf <<-EOF
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{
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"cniVersion": "0.2.0",
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"name": "mynet",
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"type": "bridge",
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"bridge": "cni0",
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"isGateway": true,
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"ipMasq": true,
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"ipam": {
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"type": "host-local",
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"subnet": "10.88.0.0/16",
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"routes": [
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{ "dst": "0.0.0.0/0" }
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]
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}
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}
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EOF'
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$ sudo sh -c 'cat >/etc/cni/net.d/99-loopback.conf <<-EOF
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{
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"cniVersion": "0.2.0",
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"type": "loopback"
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}
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EOF'
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$ ./build
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$ sudo mkdir -p /opt/cni/bin
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$ sudo cp bin/* /opt/cni/bin/
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```
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### Current Roadmap
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1. Basic pod/container lifecycle, basic image pull (already works)
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1. Support for tty handling and state management
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1. Basic integration with kubelet once client side changes are ready
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1. Support for log management, networking integration using CNI, pluggable image/storage management
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1. Support for exec/attach
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1. Target fully automated kubernetes testing without failures
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