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Container Runtime Interface (CRI) CLI

crictl provides a CLI for CRI-compatible container runtimes. This allows the CRI runtime developers to debug their runtime without needing to set up Kubernetes components.

crictl is currently in Beta and still under quick iterations. It is hosted at the cri-tools repository. We encourage the CRI developers to report bugs or help extend the coverage by adding more functionalities.

Install crictl

crictl can be downloaded from cri-tools release page:

  • using wget:
VERSION="v1.17.0"
wget https://github.com/kubernetes-sigs/cri-tools/releases/download/$VERSION/crictl-$VERSION-linux-amd64.tar.gz
sudo tar zxvf crictl-$VERSION-linux-amd64.tar.gz -C /usr/local/bin
rm -f crictl-$VERSION-linux-amd64.tar.gz
  • using curl:
VERSION="v1.17.0"
curl -L https://github.com/kubernetes-sigs/cri-tools/releases/download/$VERSION/crictl-${VERSION}-linux-amd64.tar.gz --output crictl-${VERSION}-linux-amd64.tar.gz
sudo tar zxvf crictl-$VERSION-linux-amd64.tar.gz -C /usr/local/bin
rm -f crictl-$VERSION-linux-amd64.tar.gz

Usage

crictl  [global options] command [command options] [arguments...]

COMMANDS:

  • attach: Attach to a running container
  • create: Create a new container
  • exec: Run a command in a running container
  • version: Display runtime version information
  • images, image, img: List images
  • inspect: Display the status of one or more containers
  • inspecti: Return the status of one or more images
  • imagefsinfo: Return image filesystem info
  • inspectp: Display the status of one or more pods
  • logs: Fetch the logs of a container
  • port-forward: Forward local port to a pod
  • ps: List containers
  • pull: Pull an image from a registry
  • run: Run a new container inside a sandbox
  • runp: Run a new pod
  • rm: Remove one or more containers
  • rmi: Remove one or more images
  • rmp: Remove one or more pods
  • pods: List pods
  • start: Start one or more created containers
  • info: Display information of the container runtime
  • stop: Stop one or more running containers
  • stopp: Stop one or more running pods
  • update: Update one or more running containers
  • config: Get and set crictl client configuration options
  • stats: List container(s) resource usage statistics
  • completion: Output bash shell completion code
  • help, h: Shows a list of commands or help for one command

crictl by default connects to Unix: unix:///var/run/dockershim.sock or Windows: tcp://localhost:3735. For other runtimes, use:

  • containerd: unix:///run/containerd/containerd.sock
  • cri-o: unix:///var/run/crio/crio.sock
  • frakti: unix:///var/run/frakti.sock

The endpoint can be set in three ways:

  • By setting global option flags --runtime-endpoint (-r) and --image-endpoint (-i)
  • By setting environment variables CONTAINER_RUNTIME_ENDPOINT and IMAGE_SERVICE_ENDPOINT
  • By setting the endpoint in the config file --config=/etc/crictl.yaml

If the endpoint is not set then it works as follows:

  • If the runtime endpoint is not set crictl will, by default, try to connect using:
    • dockershim
    • containerd
    • cri-o
  • If the image endpoint is not set crictl will, by default, use the runtime endpoint setting

Note: The default endpoints are now deprecated and the runtime endpoint should always be set instead. The performance maybe affected as each default connection attempt takes n-seconds to complete before timing out and going to the next in sequence.

Unix:

$ cat /etc/crictl.yaml
runtime-endpoint: unix:///var/run/dockershim.sock
image-endpoint: unix:///var/run/dockershim.sock
timeout: 2
debug: true
pull-image-on-create: false

Windows:

C:\> type %USERPROFILE%\.crictl\crictl.yaml
runtime-endpoint: tcp://localhost:3735
image-endpoint: tcp://localhost:3735
timeout: 2
debug: true
pull-image-on-create: false

Connection troubleshooting

Some runtimes might use cmux for connection multiplexing, which can cause issues during the initial gRPC connection setup. If it does not seem to be possible to connect to the runtime *.sock, then exporting the environment variable GRPC_GO_REQUIRE_HANDSHAKE=off might solve the issue. Please take into account that the environment has to be preserved when running via sudo (sudo -E crictl ...).

Additional options

  • --timeout, -t: Timeout of connecting to server in seconds (default: 2s). 0 or less is interpreted as unset and converted to the default. There is no option for no timeout value set and the smallest supported timeout is 1s
  • --debug, -D: Enable debug output
  • --help, -h: show help
  • --version, -v: print the version information of crictl
  • --config, -c: Location of the client config file. If not specified and the default does not exist, the program's directory is searched as well (default: "/etc/crictl.yaml") [$CRI_CONFIG_FILE]

Client Configuration Options

Use the crictl config command to get and set the crictl client configuration options.

USAGE:
   crictl config [command options] [<crictl options>]

For example crictl config --set debug=true will enable debug mode when giving subsequent crictl commands.

CRICTL OPTIONS:

   runtime-endpoint:       Container runtime endpoint
   image-endpoint:         Image endpoint
   timeout:                Timeout of connecting to server (default: 2s)
   debug:                  Enable debug output (default: false)
   pull-image-on-create:   Enable pulling image on create requests (default: false)
   disable-pull-on-run:    Disable pulling image on run requests (default: false)

OPTIONS:

   --get value  show the option value
   --set value  set option (can specify multiple or separate values with commas: opt1=val1,opt2=val2)
   --help, -h   show help (default: false)

When enabled pull-image-on-create modifies the create container command to first pull the container's image. This feature is used as a helper to make creating containers easier and faster. Some users of crictl may desire to not pull the image necessary to create the container. For example, the image may have already been pulled or otherwise loaded into the container runtime, or the user may be running without a network. For this reason the default for pull-image-on-create is false.

By default the run command first pulls the container image, and disable-pull-on-run is false. Some users of crictl may desire to set disable-pull-on-run to true to not pull the image by default when using the run command.

To override these default pull configuration settings, --no-pull and --with-pull options are provided for the create and run commands.

Examples

Run pod sandbox with config file

$ cat pod-config.json
{
    "metadata": {
        "name": "nginx-sandbox",
        "namespace": "default",
        "attempt": 1,
        "uid": "hdishd83djaidwnduwk28bcsb"
    },
    "log_directory": "/tmp",
    "linux": {
    }
}

$ crictl runp pod-config.json
f84dd361f8dc51518ed291fbadd6db537b0496536c1d2d6c05ff943ce8c9a54f

List pod sandboxes and check the sandbox is in Ready state:

$ crictl pods
POD ID              CREATED             STATE               NAME                NAMESPACE           ATTEMPT
f84dd361f8dc5       17 seconds ago      Ready               busybox-sandbox     default             1

Run pod sandbox with runtime handler

Runtime handler requires runtime support. The following example shows running a pod sandbox with runsc handler on containerd runtime.

$ cat pod-config.json
{
    "metadata": {
        "name": "nginx-runsc-sandbox",
        "namespace": "default",
        "attempt": 1,
        "uid": "hdishd83djaidwnduwk28bcsb"
    },
    "log_directory": "/tmp",
    "linux": {
    }
}

$ crictl runp --runtime=runsc pod-config.json
c112976cb6caa43a967293e2c62a2e0d9d8191d5109afef230f403411147548c

$ crictl inspectp c112976cb6caa43a967293e2c62a2e0d9d8191d5109afef230f403411147548c
...
    "runtime": {
      "runtimeType": "io.containerd.runtime.v1.linux",
      "runtimeEngine": "/usr/local/sbin/runsc",
      "runtimeRoot": "/run/containerd/runsc"
    },
...

Pull a busybox image

$ crictl pull busybox
Image is up to date for busybox@sha256:141c253bc4c3fd0a201d32dc1f493bcf3fff003b6df416dea4f41046e0f37d47

List images and check the busybox image has been pulled:

$ crictl images
IMAGE               TAG                 IMAGE ID            SIZE
busybox             latest              8c811b4aec35f       1.15MB
k8s.gcr.io/pause    3.1                 da86e6ba6ca19       742kB

Create container in the pod sandbox with config file

$ cat pod-config.json
{
    "metadata": {
        "name": "nginx-sandbox",
        "namespace": "default",
        "attempt": 1,
        "uid": "hdishd83djaidwnduwk28bcsb"
    },
    "log_directory": "/tmp",
    "linux": {
    }
}

$ cat container-config.json
{
  "metadata": {
      "name": "busybox"
  },
  "image":{
      "image": "busybox"
  },
  "command": [
      "top"
  ],
  "log_path":"busybox.0.log",
  "linux": {
  }
}

$ crictl create f84dd361f8dc51518ed291fbadd6db537b0496536c1d2d6c05ff943ce8c9a54f container-config.json pod-config.json
3e025dd50a72d956c4f14881fbb5b1080c9275674e95fb67f965f6478a957d60

List containers and check the container is in Created state:

$ crictl ps -a
CONTAINER ID        IMAGE               CREATED             STATE               NAME                ATTEMPT
3e025dd50a72d       busybox             32 seconds ago      Created             busybox             0

Start container

$ crictl start 3e025dd50a72d956c4f14881fbb5b1080c9275674e95fb67f965f6478a957d60
3e025dd50a72d956c4f14881fbb5b1080c9275674e95fb67f965f6478a957d60

$ crictl ps
CONTAINER ID        IMAGE               CREATED              STATE               NAME                ATTEMPT
3e025dd50a72d       busybox             About a minute ago   Running             busybox             0

Exec a command in container

crictl exec -i -t 3e025dd50a72d956c4f14881fbb5b1080c9275674e95fb67f965f6478a957d60 ls
bin   dev   etc   home  proc  root  sys   tmp   usr   var

Create and start a container within one command

It is possible to start a container within a single command, whereas the image will be pulled automatically, too:

$ cat pod-config.json
{
    "metadata": {
        "name": "nginx-sandbox",
        "namespace": "default",
        "attempt": 1,
        "uid": "hdishd83djaidwnduwk28bcsb"
    },
    "log_directory": "/tmp",
    "linux": {
    }
}

$ cat container-config.json
{
  "metadata": {
      "name": "busybox"
  },
  "image":{
      "image": "busybox"
  },
  "command": [
      "top"
  ],
  "log_path":"busybox.0.log",
  "linux": {
  }
}

$ crictl run container-config.json pod-config.json
b25b4f26e342969eb40d05e98130eee0846557d667e93deac992471a3b8f1cf4

List containers and check the container is in Running state:

$ crictl ps
CONTAINER           IMAGE               CREATED             STATE               NAME                ATTEMPT             POD ID
b25b4f26e3429       busybox:latest      14 seconds ago      Running             busybox             0                   158d7a6665ff3

More information

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Summary | 1 Annotation
runtime handler
2020/07/29 10:23