Debugging Kubernetes nodes with crictl
Kubernetes v1.11 [stable]crictl is a command-line interface for CRI-compatible container runtimes.
You can use it to inspect and debug container runtimes and applications on a
Kubernetes node. crictl and its source are hosted in the
cri-tools repository.
Before you begin
crictl requires a Linux operating system with a CRI runtime.
Installing crictl
You can download a compressed archive crictl from the cri-tools
release page, for several
different architectures. Download the version that corresponds to your version
of Kubernetes. Extract it and move it to a location on your system path, such as
/usr/local/bin/.
General usage
The crictl command has several subcommands and runtime flags. Use
crictl help or crictl <subcommand> help for more details.
You can set the endpoint for crictl by doing one of the following:
- Set the
--runtime-endpointand--image-endpointflags. - Set the
CONTAINER_RUNTIME_ENDPOINTandIMAGE_SERVICE_ENDPOINTenvironment variables. - Set the endpoint in the configuration file
/etc/crictl.yaml. To specify a different file, use the--config=PATH_TO_FILEflag when you runcrictl.
Note:
If you don't set an endpoint,crictl attempts to connect to a list of known
endpoints, which might result in an impact to performance.You can also specify timeout values when connecting to the server and enable or
disable debugging, by specifying timeout or debug values in the configuration
file or using the --timeout and --debug command-line flags.
To view or edit the current configuration, view or edit the contents of
/etc/crictl.yaml. For example, the configuration when using the containerd
container runtime would be similar to this:
runtime-endpoint: unix:///var/run/containerd/containerd.sock
image-endpoint: unix:///var/run/containerd/containerd.sock
timeout: 10
debug: true
To learn more about crictl, refer to the crictl
documentation.
Example crictl commands
The following examples show some crictl commands and example output.
List pods
List all pods:
crictl pods
The output is similar to this:
POD ID CREATED STATE NAME NAMESPACE ATTEMPT
926f1b5a1d33a About a minute ago Ready sh-84d7dcf559-4r2gq default 0
4dccb216c4adb About a minute ago Ready nginx-65899c769f-wv2gp default 0
a86316e96fa89 17 hours ago Ready kube-proxy-gblk4 kube-system 0
919630b8f81f1 17 hours ago Ready nvidia-device-plugin-zgbbv kube-system 0
List pods by name:
crictl pods --name nginx-65899c769f-wv2gp
The output is similar to this:
POD ID CREATED STATE NAME NAMESPACE ATTEMPT
4dccb216c4adb 2 minutes ago Ready nginx-65899c769f-wv2gp default 0
List pods by label:
crictl pods --label run=nginx
The output is similar to this:
POD ID CREATED STATE NAME NAMESPACE ATTEMPT
4dccb216c4adb 2 minutes ago Ready nginx-65899c769f-wv2gp default 0
List images
List all images:
crictl images
The output is similar to this:
IMAGE TAG IMAGE ID SIZE
busybox latest 8c811b4aec35f 1.15MB
k8s-gcrio.azureedge.net/hyperkube-amd64 v1.10.3 e179bbfe5d238 665MB
k8s-gcrio.azureedge.net/pause-amd64 3.1 da86e6ba6ca19 742kB
nginx latest cd5239a0906a6 109MB
List images by repository:
crictl images nginx
The output is similar to this:
IMAGE TAG IMAGE ID SIZE
nginx latest cd5239a0906a6 109MB
Only list image IDs:
crictl images -q
The output is similar to this:
sha256:8c811b4aec35f259572d0f79207bc0678df4c736eeec50bc9fec37ed936a472a
sha256:e179bbfe5d238de6069f3b03fccbecc3fb4f2019af741bfff1233c4d7b2970c5
sha256:da86e6ba6ca197bf6bc5e9d900febd906b133eaa4750e6bed647b0fbe50ed43e
sha256:cd5239a0906a6ccf0562354852fae04bc5b52d72a2aff9a871ddb6bd57553569
List containers
List all containers:
crictl ps -a
The output is similar to this:
CONTAINER ID IMAGE CREATED STATE NAME ATTEMPT
1f73f2d81bf98 busybox@sha256:141c253bc4c3fd0a201d32dc1f493bcf3fff003b6df416dea4f41046e0f37d47 7 minutes ago Running sh 1
9c5951df22c78 busybox@sha256:141c253bc4c3fd0a201d32dc1f493bcf3fff003b6df416dea4f41046e0f37d47 8 minutes ago Exited sh 0
87d3992f84f74 nginx@sha256:d0a8828cccb73397acb0073bf34f4d7d8aa315263f1e7806bf8c55d8ac139d5f 8 minutes ago Running nginx 0
1941fb4da154f k8s-gcrio.azureedge.net/hyperkube-amd64@sha256:00d814b1f7763f4ab5be80c58e98140dfc69df107f253d7fdd714b30a714260a 18 hours ago Running kube-proxy 0
List running containers:
crictl ps
The output is similar to this:
CONTAINER ID IMAGE CREATED STATE NAME ATTEMPT
1f73f2d81bf98 busybox@sha256:141c253bc4c3fd0a201d32dc1f493bcf3fff003b6df416dea4f41046e0f37d47 6 minutes ago Running sh 1
87d3992f84f74 nginx@sha256:d0a8828cccb73397acb0073bf34f4d7d8aa315263f1e7806bf8c55d8ac139d5f 7 minutes ago Running nginx 0
1941fb4da154f k8s-gcrio.azureedge.net/hyperkube-amd64@sha256:00d814b1f7763f4ab5be80c58e98140dfc69df107f253d7fdd714b30a714260a 17 hours ago Running kube-proxy 0
Execute a command in a running container
crictl exec -i -t 1f73f2d81bf98 ls
The output is similar to this:
bin dev etc home proc root sys tmp usr var
Get a container's logs
Get all container logs:
crictl logs 87d3992f84f74
The output is similar to this:
10.240.0.96 - - [06/Jun/2018:02:45:49 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.47.0" "-"
10.240.0.96 - - [06/Jun/2018:02:45:50 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.47.0" "-"
10.240.0.96 - - [06/Jun/2018:02:45:51 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.47.0" "-"
Get only the latest N lines of logs:
crictl logs --tail=1 87d3992f84f74
The output is similar to this:
10.240.0.96 - - [06/Jun/2018:02:45:51 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.47.0" "-"