JSONPath Support
JSONPath template is composed of JSONPath expressions enclosed by {}. And we add three functions in addition to the original JSONPath syntax:
- The
$operator is optional since the expression always starts from the root object by default. - We can use
""to quote text inside JSONPath expressions. - We can use
rangeoperator to iterate lists. - We can use negative slice indices to step backwards through a list. Negative indices do not “wrap around” a list. They are valid as long as
-index + listLength >= 0.
The result object is printed as its String() function.
Given the input:
{
"kind": "List",
"items":[
{
"kind":"None",
"metadata":{"name":"127.0.0.1"},
"status":{
"capacity":{"cpu":"4"},
"addresses":[{"type": "LegacyHostIP", "address":"127.0.0.1"}]
}
},
{
"kind":"None",
"metadata":{"name":"127.0.0.2"},
"status":{
"capacity":{"cpu":"8"},
"addresses":[
{"type": "LegacyHostIP", "address":"127.0.0.2"},
{"type": "another", "address":"127.0.0.3"}
]
}
}
],
"users":[
{
"name": "myself",
"user": {}
},
{
"name": "e2e",
"user": {"username": "admin", "password": "secret"}
}
]
}| Function | Description | Example | Result |
|---|---|---|---|
| text | the plain text | kind is {.kind} | kind is List |
| @ | the current object | {@} | the same as input |
| . or [] | child operator | {.kind} or {[‘kind’]} | List |
| .. | recursive descent | {..name} | 127.0.0.1 127.0.0.2 myself e2e |
| * | wildcard. Get all objects | {.items[*].metadata.name} | [127.0.0.1 127.0.0.2] |
| [start:end :step] | subscript operator | {.users[0].name} | myself |
| [,] | union operator | {.items[*][‘metadata.name’, ‘status.capacity’]} | 127.0.0.1 127.0.0.2 map[cpu:4] map[cpu:8] |
| ?() | filter | {.users[?(@.name==“e2e”)].user.password} | secret |
| range, end | iterate list | {range .items[*]}[{.metadata.name}, {.status.capacity}] {end} | [127.0.0.1, map[cpu:4]] [127.0.0.2, map[cpu:8]] |
| “ | quote interpreted string | {range .items[*]}{.metadata.name}{’\t’}{end} | 127.0.0.1 127.0.0.2 |
Below are some examples using jsonpath:
$ kubectl get pods -o json
$ kubectl get pods -o=jsonpath='{@}'
$ kubectl get pods -o=jsonpath='{.items[0]}'
$ kubectl get pods -o=jsonpath='{.items[0].metadata.name}'
$ kubectl get pods -o=jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.status.startTime}{"\n"}{end}'