Kubectl get JSONPath Support

External

• https://kubernetes.io/docs/reference/kubectl/jsonpath/

Internal

• kubectl
• JSONPath

Overview

kubectl get -o jsonpath='{<jsonpath-expression>}' ...

supports a JSONPath template, which consists in JSONPath expressions enclosed by curly braces.

kubectl get pod some-pod -o jsonpath='{.status.phase}'

The JSONPath expression are mainly used to:

• Filter the JSON content to only display specific fields in the JSON object, using filter expressions.

Note that when the result of the kubectl query contains more than one item, it is returned as a "List" top-level JSON Object, where individual results are element of an ".items" array:

{
  "apiVersion": "v1",
  "kind": "List",
  "metadata": {
    "resourceVersion": "..."
    ...
  }
  "items": [ 
    {
      "apiVersion": "v1",
      "kind": "Namespace", 
      ...
    },
    ...
  ]
}

The result should be processed as such:

kubectl get pods -o jsonpath="{.items[*]...}"

Syntax

$

• JSONPath $

Element Selection

Object Fields Selection

Individual Fields

JSONPath .field

The value of a specified field can be obtained with:

kubectl get pod <pod-name> -o jsonpath="{.status.phase}"

When more than one resource is returned as result, the result is a JSON "List" Object with an .items field, which can be queried as such:

kubectl get pods -o jsonpath="{.items[*].status.phase}"

Field Recursive Descent

All values for a specific field can be obtained recursively with:

JSONPath ..field (field recursive descent)

Array Element Selection

• JSONPath [0-based-index]
• JSONPath [index1, index2, ...]
• JSONPath [start:end], [start:]
• JSONPath [:n]
• JSONPath [-n:]

Wildcard

• JSONPath * (wildcard)

@

JSONPath @

Filter Expressions

[?(expression)]

JSONPath Filter Expressions

Organizatorium

Removing Leading and Trailing Single Quotes

... | sed -e 's/^'\''//' > ...

Get an Individual Attribute Only

TODO: https://gist.github.com/so0k/42313dbb3b547a0f51a547bb968696ba

kubectl ... -o jsonpath="{.items[?(@.spec.unschedulable)].metadata.name}"

Alternative, to explore and document:

kubectl get pods  --no-headers -o custom-columns=\":metadata.name\" ...

Filter Elements of an Array based on a Key Value

We assume that the elements of the array are maps, which contain the specified key:

kubectl ... -o jsonpath="{.users[?(@.name=="blue")].user.password}"
kubectl get pod ... -o jsonpath='{.items[0].spec.volumes[?(@.name=="vault")].hostPath.path}' 2>/dev/null

Select and Combine Two or More Elements

kubectl get pod \
-o jsonpath='{.items[0].spec.volumes[?(@.name=="A")].hostPath.path}'+'{.items[0].spec.volumes[?(@.name=="B")].hostPath.path}'

returns "/some/path/a+/some/path/b"

Same Element from Multiple Resources

kubectl get pod -o jsonpath='{.items[*].metadata.name}'

Array Length

jq Array Length

TODO

kubectl get pods -o=jsonpath='{.items[?(@.metadata.labels.name=="web")].metadata.name}'

Iterate over the Elements of an Array

kubectl get nodes -o jsonpath='{.items[*]}'

Iterate over the Elements of an Array and Select a Specific Key

kubectl get nodes -o jsonpath='{.items[*].status}'

Filter by an element:

kubectl get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="InternalIP")]}'

Print the element "address"

kubectl get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="InternalIP")].address}'