Transform functions :: Kloudfuse Docs

Transform functions

label_join

Writes a new label whose value is the values of several source labels joined with a separator. Use it to build a single display or matching key from multiple dimensions.

Syntax

label_join(<expr>, "<dst>", "<separator>", "<src1>", "<src2>", ...)

Parameters

Parameter	Required	Description
`<expr>`	Required	The expression to transform.
`<dst>`	Required	The label to write.
`<separator>`	Required	String placed between values.
`<srcN>`	Required	One or more source labels to join.

Example

Build an instance_zone key from the service name and availability zone of Kloudfuse query-service pods.

label_join(
  sum by (app_kubernetes_io_name, availability_zone) (go_goroutines{app_kubernetes_io_name="query-service"}),
  "instance_zone", "/", "app_kubernetes_io_name", "availability_zone"
)

instance_zone	Value
query-service/canadacentral-1	22
query-service/us-central1-a	2,473
query-service/ap-south-1a	1,029
query-service/us-gov-west-1a	22
query-service/us-west1-a	5,483

Expected output


	Missing source labels contribute an empty string.

label_replace

Adds or overwrites a label on every series by matching a regular expression against an existing label and expanding a replacement template with the capture groups. Series whose source label does not match pass through unchanged.

Syntax

label_replace(<expr>, "<dst>", "<replacement>", "<src>", "<regex>")

Parameters

Parameter	Required	Description
`<expr>`	Required	The expression to transform.
`<dst>`	Required	The label to write.
`<replacement>`	Required	Template for the new value; `$1`, `$2` reference capture groups.
`<src>`	Required	The label to match against.
`<regex>`	Required	An anchored RE2 expression.

Example

Derive a short service label from app_kubernetes_io_name by stripping the -service suffix.

label_replace(
  sum by (app_kubernetes_io_name) (go_goroutines{app_kubernetes_io_name=~".*query-service"}),
  "service", "$1", "app_kubernetes_io_name", "(.*)-service"
)

service	Value
rum-query	1,316
query	64,523
trace-query	3,058
logs-query	19,486
events-query	3,019

Expected output


	The source label is left untouched; drop it from view with a surrounding aggregation if needed.

sort_desc

Orders the series of an instant query by value, largest first — the natural order for leaderboard-style panels.

Syntax

sort_desc(<expr>)

Example

List Kloudfuse query services from most to fewest goroutines.

sort_desc(sum by (app_kubernetes_io_name) (go_goroutines{app_kubernetes_io_name=~".*query-service"}))

app_kubernetes_io_name	Value
query-service	64,589
logs-query-service	19,522
trace-query-service	3,060
events-query-service	3,018
rum-query-service	1,315

Expected output


	In range queries, sorting has no effect — each step is evaluated independently.

sort

Orders the series of an instant query by value, smallest first. Sorting affects presentation only — labels and values are unchanged — and applies to instant queries, where the result is a flat list.

Syntax

sort(<expr>)

Example

List Kloudfuse query services from fewest to most goroutines.

sort(sum by (app_kubernetes_io_name) (go_goroutines{app_kubernetes_io_name=~".*query-service"}))

app_kubernetes_io_name	Value
rum-query-service	1,319
events-query-service	3,019
trace-query-service	3,057
logs-query-service	19,524
query-service	64,559

Expected output


	To limit as well as order, use `topk`/`bottomk`.