Kubernetes CRI containerd integration by Lantao Liu (Google)
19
Kubernetes Container Integration - CRI-Container 14 Sept, 2017 Lantao Liu <Random-Liu@github> Google Kubernetes Abhinandan Prativadi <abhinandanpb@github> Docker
-
Upload
docker-inc -
Category
Technology
-
view
19.320 -
download
0
Transcript of Kubernetes CRI containerd integration by Lantao Liu (Google)
Kubernetes Container Integration - CRI-Container14 Sept, 2017
Lantao Liu <Random-Liu@github> Google Kubernetes
Abhinandan Prativadi <abhinandanpb@github> Docker
Contents
● Container Runtime Interface (CRI)
● CRI & Containerd
● CRI-Containerd
● Q & A
Contents
● Container Runtime Interface (CRI)
● CRI & Containerd
● CRI-Containerd
● Q & A
Container Runtime Interface
● What is Container Runtime Interface (CRI) ?
○ A gRPC interface and a group of libraries
○ Enables Kubernetes to use a wide variety of container runtimes
○ Introduced in Kubernetes 1.5
Kubelet
CRIgRPCclient
CRI shim
CRIgRPC
server
container runtime
containercontainer
containercontainer
container
Container Runtime Interface
● CRI Runtimes
○ cri-containerd: https://github.com/kubernetes-incubator/cri-containerd
○ cri-o: https://github.com/kubernetes-incubator/cri-o
○ Docker (Upstream):
https://github.com/kubernetes/kubernetes/tree/master/pkg/kubelet/dockershim
○ frakti: https://github.com/kubernetes/frakti
○ rktlet: https://github.com/kubernetes-incubator/rktlet
○ virtlet: https://github.com/Mirantis/virtlet
● CRI Tools https://github.com/kubernetes-incubator/cri-tools○ critest: CRI Validation Test Suite
○ crictl: CRI Command Line Tool
Contents
● Container Runtime Interface (CRI)
● CRI & Containerd
● CRI-Containerd
● Q & A
CRI & Containerd
● The scope of containerd 1.0 aligns with the requirement of CRI.
Name CRI Requirement Containerd 1.0 Scope
Container Lifecycle
Management
Create/Start/Stop/Delete/Lis
t/InspectIn
Image Management Pull/List/Inspect In
Networking
K8s handles pod and
service network, container
runtime SHOULD NOT
provide extra network
solution.
OutNo concrete network solution.
User can setup network
namespace, and put container
into it.
CRI & Containerd
● Continued
Name CRI Requirement Containerd Scope
Volumes
K8s manages volumes.
Container runtime SHOULD
NOT provide extra volume
support.
OutNo volume management. User
can setup host path, and
mount into container.
Persistent Container
Logging
K8s has specific
requirements for persistent
container logging, namely
format and path. Container
runtime SHOULD NOT
persist an unmanageable
log.
OutNo persistent container
logging. Container stdio is
provided as FIFOs, which can
be redirected/decorated as is
required.
CRI & Containerd
● Continued
Name CRI Requirement Containerd Scope
Metrics
K8s expects container
runtime to provide container
metrics (CPU, Memory,
Writable Layer Size etc.)
and image filesystem usage.
InContainerd provides these
metrics as part of the API.
CRI & Containerd
● Other alignments with Kubernetes:
○ Decentralized container management - containerd-shim.
■ Live restore.
■ Charge container management overhead to corresponding pod.
○ Decoupled image and container management.
■ Support other image formats (e.g. tarball)
○ Extensible image management:
■ Client-driven Image Download
■ Snapshotter
○ Support OCI image/runtime spec.
○ CNCF project.
○ ...
Contents
● Container Runtime Interface (CRI)
● CRI & Containerd
● CRI-Containerd
● Q & A
CRI-Containerd
● cri-containerd: A containerd based implementation of CRI.
○ https://github.com/kubernetes-incubator/cri-containerd
○ Kubernetes incubator project.
○ Started in April 2017.
containercontainerKubelet dockershim dockercontainer
d containercontainer
CRI
containercontainerKubelet cri-containerd
containerd
containercontainer
CRI
dockershim
cri-containerd
CRI-Containerd Architecture
Pod B
Pod A Cgroups
Pod A Namespaces
cri-containerd
sandbox container
containerd shim
image service
runtime service
Kubelet
gRPCClient
containerd shim
container A
ocicni
CRI-Containerd Status
● Dependencies:
○ Kubernetes: >= v1.7
○ containerd: v1.0.0-beta.0 (daily/weekly update)
○ CNI: v0.6.0 (Spec Version: 0.3.1)
● All features in CRI (K8s 1.8) supported other than 3 missing features being added soon:
○ Seccomp. Under review.
○ Metrics. Kubelet and containerd changes merged, cri-containerd support in 1-2 weeks.○ Mount Propagation (K8s 1.8): Under review.
● 37/37 CRI validation tests passing (Per-PR test)
● 180/182 node e2e tests passing (Per-PR test)○ Running the same set of K8s PR node e2e test.
○ 2 test failures:
CRI-Containerd Plan for 2017
● 1.0.0-alpha.0 by the end of September.○ Feature Complete.
○ All Kubernetes PR node e2e tests passing.
○ Use kubeadm to bring up Kubernetes cri-containerd cluster.
○ Release tarball for distribution and installation.
● Q4: Additional testing, bug fixes and documentation.○ Test: Setup FULL SET of node/cluster e2e test in Kubernetes test infra.
■ Suites: Slow, Serial, Reboot, Performance etc.
■ OS: Ubuntu, COS (Container-Optimized OS) etc.
○ Ease of use:
■ Documentation.
■ Polish kubeadm integration.
■ kube-up.sh integration.
○ 1.0.0-beta.0 by the end of 2017.
Demo
● Demo Focus:
○ Installation
○ Cluster lifecycle
○ Networking
○ Namespace management
○ Mount Propagation
○ Pod operations
○ Sample Demo App
Recap
● CRI is the standard way to integrate Container Runtime with
Kubernetes.
● New containerd matches CRI and Kubernetes’ requirement very well.
● CRI-Containerd 1.0.0-alpha.0 is releasing by the end of September. It
will be feature complete.
Links
● Github: https://github.com/kubernetes-incubator/cri-containerd
● Slack: https://kubernetes.slack.com/messages/sig-node
● Mailing List: https://groups.google.com/forum/#!forum/kubernetes-
sig-node
● Maintainers:
○ Lantao Liu <[email protected]>
○ Abhi Prativadi <[email protected]>
○ Mike Brown <[email protected]>
Q & A
