This document presumes you already have containerd
with the cri
plugin installed and running.
This document is for developers who wish to debug, inspect, and manage their pods, containers, and container images.
Before generating issues against this document, containerd
, containerd/cri
,
or crictl
please make sure the issue has not already been submitted.
If you have not already installed crictl please install the version compatible
with the cri
plugin you are using. If you are a user, your deployment
should have installed crictl for you. If not, get it from your release tarball.
If you are a developer the current version of crictl is specified here.
A helper command has been included to install the dependencies at the right version:
$ make install.deps
- Note: The file named
/etc/crictl.yaml
is used to configure crictl so you don't have to repeatedly specify the runtime sock used to connect crictl to the container runtime:
$ cat /etc/crictl.yaml
runtime-endpoint: /run/containerd/containerd.sock
image-endpoint: /run/containerd/containerd.sock
timeout: 10
debug: true
The pull command tells the container runtime to download a container image from a container registry.
$ crictl pull busybox
...
$ crictl inspecti busybox
... displays information about the image.
Another way to load an image into the container runtime is with the load command. With the load command you inject a container image into the container runtime from a file. First you need to create a container image tarball. For example to create an image tarball for a pause container using Docker:
$ docker pull k8s.gcr.io/pause-amd64:3.1
3.1: Pulling from pause-amd64
67ddbfb20a22: Pull complete
Digest: sha256:59eec8837a4d942cc19a52b8c09ea75121acc38114a2c68b98983ce9356b8610
Status: Downloaded newer image for k8s.gcr.io/pause-amd64:3.1
$ docker save k8s.gcr.io/pause-amd64:3.1 -o pause.tar
Then use ctr
to load the container image into the container runtime:
$ sudo ctr cri load pause.tar
Loaded image: k8s.gcr.io/pause-amd64:3.1
List images and inspect the pause image:
$ sudo crictl images
IMAGE TAG IMAGE ID SIZE
docker.io/library/busybox latest f6e427c148a76 728kB
k8s.gcr.io/pause-amd64 3.1 da86e6ba6ca19 746kB
$ sudo crictl inspecti da86e6ba6ca19
... displays information about the pause image.
$ sudo crictl inspecti k8s.gcr.io/pause-amd64:3.1
... displays information about the pause image.
$ cat sandbox-config.json
{
"metadata": {
"name": "nginx-sandbox",
"namespace": "default",
"attempt": 1,
"uid": "hdishd83djaidwnduwk28bcsb"
},
"linux": {
}
}
$ crictl runp sandbox-config.json
e1c83b0b8d481d4af8ba98d5f7812577fc175a37b10dc824335951f52addbb4e
$ crictl pods
PODSANDBOX ID CREATED STATE NAME NAMESPACE ATTEMPT
e1c83b0b8d481 2 hours ago SANDBOX_READY nginx-sandbox default 1
$ crictl inspectp e1c8
... displays information about the pod and the pod sandbox pause container.
- Note: As shown above, you may use truncated IDs if they are unique.
- Other commands to manage the pod include
stops ID
to stop a running pod andrmp ID
to remove a pod sandbox.
$ cat container-config.json
{
"metadata": {
"name": "busybox"
},
"image":{
"image": "busybox"
},
"command": [
"top"
],
"linux": {
}
}
$ crictl create e1c83 container-config.json sandbox-config.json
0a2c761303163f2acaaeaee07d2ba143ee4cea7e3bde3d32190e2a36525c8a05
$ crictl ps -a
CONTAINER ID IMAGE CREATED STATE NAME ATTEMPT
0a2c761303163 docker.io/busybox 2 hours ago CONTAINER_CREATED busybox 0
$ crictl start 0a2c
0a2c761303163f2acaaeaee07d2ba143ee4cea7e3bde3d32190e2a36525c8a05
$ crictl ps
CONTAINER ID IMAGE CREATED STATE NAME ATTEMPT
0a2c761303163 docker.io/busybox 2 hours ago CONTAINER_RUNNING busybox 0
$ crictl inspect 0a2c7
... show detailed information about the container
$ crictl exec -i -t 0a2c ls
bin dev etc home proc root sys tmp usr var
$ crictl stats
CONTAINER CPU % MEM DISK INODES
0a2c761303163f 0.00 983kB 16.38kB 6
- Other commands to manage the container include
stop ID
to stop a running container andrm ID
to remove a container.
$ crictl version
Version: 0.1.0
RuntimeName: containerd
RuntimeVersion: 1.0.0-beta.1-186-gdd47a72-TEST
RuntimeApiVersion: v1alpha2
$ crictl info
{
"status": {
"conditions": [
{
"type": "RuntimeReady",
"status": true,
"reason": "",
"message": ""
},
{
"type": "NetworkReady",
"status": true,
"reason": "",
"message": ""
}
]
},
"config": {
"containerd": {
"snapshotter": "overlayfs",
"runtime": "io.containerd.runtime.v1.linux"
},
"cni": {
"binDir": "/opt/cni/bin",
"confDir": "/etc/cni/net.d"
},
"registry": {
"mirrors": {
"docker.io": {
"endpoint": [
"https://registry-1.docker.io"
]
}
}
},
"streamServerPort": "10010",
"sandboxImage": "k8s.gcr.io/pause:3.1",
"statsCollectPeriod": 10,
"containerdRootDir": "/var/lib/containerd",
"containerdEndpoint": "/run/containerd/containerd.sock",
"rootDir": "/var/lib/containerd/io.containerd.grpc.v1.cri",
"stateDir": "/run/containerd/io.containerd.grpc.v1.cri",
},
"golang": "go1.10"
}
See here for information about crictl.