Kubectl JsonPath
Kubectl JsonPath
Let us display the result of kubectl get nodes in the JSON format.
First, in plain text
lab@k8s1:~$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8s1 Ready control-plane,master 2d12h v1.22.8
k8s2 Ready <none> 2d11h v1.22.8
k8s3 Ready <none> 2d9h v1.22.8
lab@k8s1:~$
lab@k8s1:~$ kubectl get nodes -o json
{
"apiVersion": "v1",
"items": [
{
"apiVersion": "v1",
"kind": "Node",
"metadata": {
"annotations": {
"flannel.alpha.coreos.com/backend-data": "{\"VNI\":1,\"VtepMAC\":\"52:1d:12:10:50:8f\"}",
"flannel.alpha.coreos.com/backend-type": "vxlan",
"flannel.alpha.coreos.com/kube-subnet-manager": "true",
"flannel.alpha.coreos.com/public-ip": "10.210.40.172",
"kubeadm.alpha.kubernetes.io/cri-socket": "/var/run/dockershim.sock",
"node.alpha.kubernetes.io/ttl": "0",
"volumes.kubernetes.io/controller-managed-attach-detach": "true"
},
"creationTimestamp": "2022-03-29T14:16:22Z",
"labels": {
"beta.kubernetes.io/arch": "amd64",
"beta.kubernetes.io/os": "linux",
"kubernetes.io/arch": "amd64",
"kubernetes.io/hostname": "k8s1",
"kubernetes.io/os": "linux",
"node-role.kubernetes.io/control-plane": "",
"node-role.kubernetes.io/master": "",
"node.kubernetes.io/exclude-from-external-load-balancers": ""
},
"name": "k8s1",
"resourceVersion": "221514",
"uid": "97295130-f079-420c-a18a-1782471530ea"
},
"spec": {
"podCIDR": "10.244.0.0/24",
"podCIDRs": [
"10.244.0.0/24"
],
"taints": [
{
"effect": "NoSchedule",
"key": "node-role.kubernetes.io/master"
}
]
},
"status": {
"addresses": [
{
"address": "10.210.40.172",
"type": "InternalIP"
},
{
"address": "k8s1",
"type": "Hostname"
}
],
"allocatable": {
"cpu": "2",
"ephemeral-storage": "59278082360",
"hugepages-2Mi": "0",
"memory": "1922804Ki",
"pods": "110"
},
"capacity": {
"cpu": "2",
"ephemeral-storage": "64320836Ki",
"hugepages-2Mi": "0",
"memory": "2025204Ki",
"pods": "110"
},
"conditions": [
{
"lastHeartbeatTime": "2022-03-29T14:20:58Z",
"lastTransitionTime": "2022-03-29T14:20:58Z",
"message": "Flannel is running on this node",
"reason": "FlannelIsUp",
"status": "False",
"type": "NetworkUnavailable"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T14:16:19Z",
"message": "kubelet has sufficient memory available",
"reason": "KubeletHasSufficientMemory",
"status": "False",
"type": "MemoryPressure"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T14:16:19Z",
"message": "kubelet has no disk pressure",
"reason": "KubeletHasNoDiskPressure",
"status": "False",
"type": "DiskPressure"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T14:16:19Z",
"message": "kubelet has sufficient PID available",
"reason": "KubeletHasSufficientPID",
"status": "False",
"type": "PIDPressure"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T18:14:07Z",
"message": "kubelet is posting ready status. AppArmor enabled",
"reason": "KubeletReady",
"status": "True",
"type": "Ready"
}
],
"daemonEndpoints": {
"kubeletEndpoint": {
"Port": 10250
}
},
"images": [
{
"names": [
"k8s.gcr.io/etcd@sha256:9ce33ba33d8e738a5b85ed50b5080ac746deceed4a7496c550927a7a19ca3b6d",
"k8s.gcr.io/etcd:3.5.0-0"
],
"sizeBytes": 294536887
},
{
"names": [
"k8s.gcr.io/kube-apiserver@sha256:c2235616f1fbb21e13876cffb72d94241c560b1829fc3820d9a9e5ffb2cfa8e8",
"k8s.gcr.io/kube-apiserver:v1.22.8"
],
"sizeBytes": 128364093
},
{
"names": [
"k8s.gcr.io/kube-controller-manager@sha256:7be1045265f305ce7c827af613411986eb1c437ed370939800f29ed6d6b1c941",
"k8s.gcr.io/kube-controller-manager:v1.22.8"
],
"sizeBytes": 122052768
},
{
"names": [
"k8s.gcr.io/kube-proxy@sha256:46c852ee61a7ea0cdc020ccb46028a6783336548074f86ab22e26945ffe31f98",
"k8s.gcr.io/kube-proxy:v1.22.8"
],
"sizeBytes": 103669604
},
{
"names": [
"rancher/mirrored-flannelcni-flannel@sha256:4bf659e449be809763b04f894f53a3d8610e00cf2cd979bb4fffc9470eb40d1b",
"rancher/mirrored-flannelcni-flannel:v0.17.0"
],
"sizeBytes": 59803434
},
{
"names": [
"k8s.gcr.io/kube-scheduler@sha256:ae27af87fe15a0cb36c10409eef35363d68243ab3c6e888fc9adf7a0ed858f1e",
"k8s.gcr.io/kube-scheduler:v1.22.8"
],
"sizeBytes": 52707184
},
{
"names": [
"k8s.gcr.io/coredns/coredns@sha256:6e5a02c21641597998b4be7cb5eb1e7b02c0d8d23cce4dd09f4682d463798890",
"k8s.gcr.io/coredns/coredns:v1.8.4"
],
"sizeBytes": 47554275
},
{
"names": [
"rancher/mirrored-flannelcni-flannel-cni-plugin@sha256:5dd61f95e28fa7ef897ff2fa402ce283e5078d334401d2f62d00a568f779f2d5",
"rancher/mirrored-flannelcni-flannel-cni-plugin:v1.0.1"
],
"sizeBytes": 8098691
},
{
"names": [
"k8s.gcr.io/pause@sha256:1ff6c18fbef2045af6b9c16bf034cc421a29027b800e4f9b68ae9b1cb3e9ae07",
"k8s.gcr.io/pause:3.5"
],
"sizeBytes": 682696
},
{
"names": [
"hello-world@sha256:bfea6278a0a267fad2634554f4f0c6f31981eea41c553fdf5a83e95a41d40c38",
"hello-world:latest"
],
"sizeBytes": 13256
}
],
"nodeInfo": {
"architecture": "amd64",
"bootID": "79681989-c2a6-478c-bb51-7c46b1596fba",
"containerRuntimeVersion": "docker://20.10.14",
"kernelVersion": "5.13.0-37-generic",
"kubeProxyVersion": "v1.22.8",
"kubeletVersion": "v1.22.8",
"machineID": "596c7f47034440028cd05f4d0fa9c753",
"operatingSystem": "linux",
"osImage": "Ubuntu 20.04.4 LTS",
"systemUUID": "18962942-410c-c225-65ca-e0a7de38d7cd"
}
}
},
{
"apiVersion": "v1",
"kind": "Node",
"metadata": {
"annotations": {
"flannel.alpha.coreos.com/backend-data": "{\"VNI\":1,\"VtepMAC\":\"92:01:5e:01:fe:01\"}",
"flannel.alpha.coreos.com/backend-type": "vxlan",
"flannel.alpha.coreos.com/kube-subnet-manager": "true",
"flannel.alpha.coreos.com/public-ip": "10.210.40.173",
"kubeadm.alpha.kubernetes.io/cri-socket": "/var/run/dockershim.sock",
"node.alpha.kubernetes.io/ttl": "0",
"volumes.kubernetes.io/controller-managed-attach-detach": "true"
},
"creationTimestamp": "2022-03-29T15:29:34Z",
"labels": {
"beta.kubernetes.io/arch": "amd64",
"beta.kubernetes.io/os": "linux",
"kubernetes.io/arch": "amd64",
"kubernetes.io/hostname": "k8s2",
"kubernetes.io/os": "linux"
},
"name": "k8s2",
"resourceVersion": "221513",
"uid": "f5c6831f-f3a5-4a67-b472-5f1dc70f017e"
},
"spec": {
"podCIDR": "10.244.2.0/24",
"podCIDRs": [
"10.244.2.0/24"
]
},
"status": {
"addresses": [
{
"address": "10.210.40.173",
"type": "InternalIP"
},
{
"address": "k8s2",
"type": "Hostname"
}
],
"allocatable": {
"cpu": "2",
"ephemeral-storage": "59278082360",
"hugepages-2Mi": "0",
"memory": "1922804Ki",
"pods": "110"
},
"capacity": {
"cpu": "2",
"ephemeral-storage": "64320836Ki",
"hugepages-2Mi": "0",
"memory": "2025204Ki",
"pods": "110"
},
"conditions": [
{
"lastHeartbeatTime": "2022-03-29T15:29:40Z",
"lastTransitionTime": "2022-03-29T15:29:40Z",
"message": "Flannel is running on this node",
"reason": "FlannelIsUp",
"status": "False",
"type": "NetworkUnavailable"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T15:29:34Z",
"message": "kubelet has sufficient memory available",
"reason": "KubeletHasSufficientMemory",
"status": "False",
"type": "MemoryPressure"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T15:29:34Z",
"message": "kubelet has no disk pressure",
"reason": "KubeletHasNoDiskPressure",
"status": "False",
"type": "DiskPressure"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T15:29:34Z",
"message": "kubelet has sufficient PID available",
"reason": "KubeletHasSufficientPID",
"status": "False",
"type": "PIDPressure"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T18:22:47Z",
"message": "kubelet is posting ready status. AppArmor enabled",
"reason": "KubeletReady",
"status": "True",
"type": "Ready"
}
],
"daemonEndpoints": {
"kubeletEndpoint": {
"Port": 10250
}
},
"images": [
{
"names": [
"k8s.gcr.io/kube-proxy@sha256:46c852ee61a7ea0cdc020ccb46028a6783336548074f86ab22e26945ffe31f98",
"k8s.gcr.io/kube-proxy:v1.22.8"
],
"sizeBytes": 103669604
},
{
"names": [
"rancher/mirrored-flannelcni-flannel@sha256:4bf659e449be809763b04f894f53a3d8610e00cf2cd979bb4fffc9470eb40d1b",
"rancher/mirrored-flannelcni-flannel:v0.17.0"
],
"sizeBytes": 59803434
},
{
"names": [
"k8s.gcr.io/coredns/coredns@sha256:6e5a02c21641597998b4be7cb5eb1e7b02c0d8d23cce4dd09f4682d463798890",
"k8s.gcr.io/coredns/coredns:v1.8.4"
],
"sizeBytes": 47554275
},
{
"names": [
"gcr.io/google-samples/hello-app@sha256:88b205d7995332e10e836514fbfd59ecaf8976fc15060cd66e85cdcebe7fb356",
"gcr.io/google-samples/hello-app:1.0"
],
"sizeBytes": 11480274
},
{
"names": [
"rancher/mirrored-flannelcni-flannel-cni-plugin@sha256:5dd61f95e28fa7ef897ff2fa402ce283e5078d334401d2f62d00a568f779f2d5",
"rancher/mirrored-flannelcni-flannel-cni-plugin:v1.0.1"
],
"sizeBytes": 8098691
},
{
"names": [
"k8s.gcr.io/pause@sha256:1ff6c18fbef2045af6b9c16bf034cc421a29027b800e4f9b68ae9b1cb3e9ae07",
"k8s.gcr.io/pause:3.5"
],
"sizeBytes": 682696
},
{
"names": [
"hello-world@sha256:bfea6278a0a267fad2634554f4f0c6f31981eea41c553fdf5a83e95a41d40c38",
"hello-world:latest"
],
"sizeBytes": 13256
}
],
"nodeInfo": {
"architecture": "amd64",
"bootID": "ed911925-bdd7-4d98-aa4e-eaa3a689bad2",
"containerRuntimeVersion": "docker://20.10.14",
"kernelVersion": "5.13.0-37-generic",
"kubeProxyVersion": "v1.22.8",
"kubeletVersion": "v1.22.8",
"machineID": "596c7f47034440028cd05f4d0fa9c753",
"operatingSystem": "linux",
"osImage": "Ubuntu 20.04.4 LTS",
"systemUUID": "02cd2942-ef22-71c9-90d0-54187982487f"
}
}
},
{
"apiVersion": "v1",
"kind": "Node",
"metadata": {
"annotations": {
"flannel.alpha.coreos.com/backend-data": "{\"VNI\":1,\"VtepMAC\":\"46:57:f7:c6:05:51\"}",
"flannel.alpha.coreos.com/backend-type": "vxlan",
"flannel.alpha.coreos.com/kube-subnet-manager": "true",
"flannel.alpha.coreos.com/public-ip": "10.210.40.175",
"kubeadm.alpha.kubernetes.io/cri-socket": "/var/run/dockershim.sock",
"node.alpha.kubernetes.io/ttl": "0",
"volumes.kubernetes.io/controller-managed-attach-detach": "true"
},
"creationTimestamp": "2022-03-29T17:00:06Z",
"labels": {
"beta.kubernetes.io/arch": "amd64",
"beta.kubernetes.io/os": "linux",
"kubernetes.io/arch": "amd64",
"kubernetes.io/hostname": "k8s3",
"kubernetes.io/os": "linux"
},
"name": "k8s3",
"resourceVersion": "221512",
"uid": "9e27cee3-6769-4bbc-bfd3-d3d5d2067ab7"
},
"spec": {
"podCIDR": "10.244.3.0/24",
"podCIDRs": [
"10.244.3.0/24"
]
},
"status": {
"addresses": [
{
"address": "10.210.40.175",
"type": "InternalIP"
},
{
"address": "k8s3",
"type": "Hostname"
}
],
"allocatable": {
"cpu": "2",
"ephemeral-storage": "59278082360",
"hugepages-2Mi": "0",
"memory": "1922804Ki",
"pods": "110"
},
"capacity": {
"cpu": "2",
"ephemeral-storage": "64320836Ki",
"hugepages-2Mi": "0",
"memory": "2025204Ki",
"pods": "110"
},
"conditions": [
{
"lastHeartbeatTime": "2022-03-29T17:00:29Z",
"lastTransitionTime": "2022-03-29T17:00:29Z",
"message": "Flannel is running on this node",
"reason": "FlannelIsUp",
"status": "False",
"type": "NetworkUnavailable"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T17:00:06Z",
"message": "kubelet has sufficient memory available",
"reason": "KubeletHasSufficientMemory",
"status": "False",
"type": "MemoryPressure"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T17:00:06Z",
"message": "kubelet has no disk pressure",
"reason": "KubeletHasNoDiskPressure",
"status": "False",
"type": "DiskPressure"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T17:00:06Z",
"message": "kubelet has sufficient PID available",
"reason": "KubeletHasSufficientPID",
"status": "False",
"type": "PIDPressure"
},
{
"lastHeartbeatTime": "2022-04-01T02:29:11Z",
"lastTransitionTime": "2022-03-29T18:32:13Z",
"message": "kubelet is posting ready status. AppArmor enabled",
"reason": "KubeletReady",
"status": "True",
"type": "Ready"
}
],
"daemonEndpoints": {
"kubeletEndpoint": {
"Port": 10250
}
},
"images": [
{
"names": [
"k8s.gcr.io/kube-proxy@sha256:46c852ee61a7ea0cdc020ccb46028a6783336548074f86ab22e26945ffe31f98",
"k8s.gcr.io/kube-proxy:v1.22.8"
],
"sizeBytes": 103669604
},
{
"names": [
"rancher/mirrored-flannelcni-flannel@sha256:4bf659e449be809763b04f894f53a3d8610e00cf2cd979bb4fffc9470eb40d1b",
"rancher/mirrored-flannelcni-flannel:v0.17.0"
],
"sizeBytes": 59803434
},
{
"names": [
"k8s.gcr.io/coredns/coredns@sha256:6e5a02c21641597998b4be7cb5eb1e7b02c0d8d23cce4dd09f4682d463798890",
"k8s.gcr.io/coredns/coredns:v1.8.4"
],
"sizeBytes": 47554275
},
{
"names": [
"gcr.io/google-samples/hello-app@sha256:88b205d7995332e10e836514fbfd59ecaf8976fc15060cd66e85cdcebe7fb356",
"gcr.io/google-samples/hello-app:1.0"
],
"sizeBytes": 11480274
},
{
"names": [
"rancher/mirrored-flannelcni-flannel-cni-plugin@sha256:5dd61f95e28fa7ef897ff2fa402ce283e5078d334401d2f62d00a568f779f2d5",
"rancher/mirrored-flannelcni-flannel-cni-plugin:v1.0.1"
],
"sizeBytes": 8098691
},
{
"names": [
"k8s.gcr.io/pause@sha256:1ff6c18fbef2045af6b9c16bf034cc421a29027b800e4f9b68ae9b1cb3e9ae07",
"k8s.gcr.io/pause:3.5"
],
"sizeBytes": 682696
},
{
"names": [
"hello-world@sha256:bfea6278a0a267fad2634554f4f0c6f31981eea41c553fdf5a83e95a41d40c38",
"hello-world:latest"
],
"sizeBytes": 13256
}
],
"nodeInfo": {
"architecture": "amd64",
"bootID": "3c77369e-54ee-471e-979c-7c730ee356d8",
"containerRuntimeVersion": "docker://20.10.14",
"kernelVersion": "5.13.0-37-generic",
"kubeProxyVersion": "v1.22.8",
"kubeletVersion": "v1.22.8",
"machineID": "596c7f47034440028cd05f4d0fa9c753",
"operatingSystem": "linux",
"osImage": "Ubuntu 20.04.4 LTS",
"systemUUID": "e6ee2942-fc1b-488a-6add-25e5744a15ee"
}
}
}
],
"kind": "List",
"metadata": {
"resourceVersion": "",
"selfLink": ""
}
}
lab@k8s1:~$
lab@k8s1:~$ kubectl get nodes -o jsonpath="{$.items[*].metadata.name}"
k8s1 k8s2 k8s3lab@k8s1:~$
lab@k8s1:~$ kubectl get nodes -o jsonpath="{$.items[0].metadata.name}"
k8s1lab@k8s1:~$ kubectl get nodes -o jsonpath="{$.items[1].metadata.name}"
k8s2lab@k8s1:~$ kubectl get nodes -o jsonpath="{$.items[2].metadata.name}"
k8s3lab@k8s1:~$
Another example
lab@k8s1:~$ kubectl get nodes -o jsonpath="{$.items[*].spec.podCIDR}"
10.244.0.0/24 10.244.2.0/24 10.244.3.0/24lab@k8s1:~$
Let us format it a bit, so that we get each of them in a new line,
lab@k8s1:~$ kubectl get nodes -o jsonpath='{range.items[*]} {.spec.podCIDR} {"\n"}'
10.244.0.0/24
10.244.2.0/24
10.244.3.0/24
lab@k8s1:~$
Looping through all items showing multiple columns
lab@k8s1:~$ kubectl get nodes -o jsonpath'{range.items[*]} {.metadata.name} {"\t"} {.status.capacity.cpu} {"\n"} {end}'
k8s1 2
k8s2 2
k8s3 2
Custom-Columns
Make use of the -o=custom-columns option to change the default output of kubectl commands.
Here is a simple example
b@k8s1:~$ kubectl get nodes -o=custom-columns=PodCIDR:.spec.podCIDR
PodCIDR
10.244.0.0/24
10.244.2.0/24
10.244.3.0/24
Another one, with two columns
lab@k8s1:~$ kubectl get nodes -o=custom-columns=PodCIDR:.spec.podCIDR,CPU:.status.capacity.cpu
PodCIDR CPU
10.244.0.0/24 2
10.244.2.0/24 2
10.244.3.0/24 2
One more,
lab@k8s1:~$ kubectl get nodes -o=custom-columns=PodCIDR:.spec.podCIDR,CPU:.status.capacity.cpu,NAME:.metadata.name
PodCIDR CPU NAME
10.244.0.0/24 2 k8s1
10.244.2.0/24 2 k8s2
10.244.3.0/24 2 k8s3
lab@k8s1:~$
One thing to note, is that , with multiple columns, ensure that there is no extra space after each column followed by a comma
(,).
lab@k8s1:~$ kubectl get nodes -o=custom-columns=PodCIDR:.spec.podCIDR, CPU:.status.capacity.cpu,NAME:.metadata.name
Error from server (NotFound): nodes "CPU:.status.capacity.cpu,NAME:.metadata.name" not found
lab@k8s1:~$
We have an extra space before CPU column name, hence the error.
Let us conclude with one more example, by modifying the kubectl get pods output, by just showing the name of the Pod and namespace.
lab@k8s1:~$ kubectl get pods -o=custom-columns=NAME:.metadata.name,NS:.metadata.namespace
NAME NS
web-79d88c97d6-4w4nl default
web-79d88c97d6-7ktck default
web-79d88c97d6-8tvsk default
web-79d88c97d6-96sd9 default
web-79d88c97d6-9tzlh default
web-79d88c97d6-brtgx default
web-79d88c97d6-kngc4 default
web-79d88c97d6-p5vfg default
web-79d88c97d6-rbhpr default
lab@k8s1:~$
