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docs :: querying :: functions :: label_replace

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Clarify documentation for label_replace() because of ambiguities
between label keys and label values.

Signed-off-by: Matthew Smedberg <matthew.smedberg@gmail.com>
This commit is contained in:
Matthew Smedberg 2021-04-27 10:15:45 -06:00 committed by berg
parent e36e5fa833
commit 8490273bac
1 changed files with 8 additions and 10 deletions
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18
docs/querying/functions.md
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@ -272,7 +272,7 @@ For each timeseries in `v`, `label_join(v instant-vector, dst_label string, sepa
using `separator` and returns the timeseries with the label `dst_label` containing the joined value.
There can be any number of `src_labels` in this function.
This example will return a vector with each time series having a `foo` label with the value `a,b,c` added to it:
This example will return a vector with each time series having a `foo` label added to it, with the value `a,b,c`:
```
label_join(up{job="api-server",src1="a",src2="b",src3="c"}, "foo", ",", "src1", "src2", "src3")
@ -280,16 +280,14 @@ label_join(up{job="api-server",src1="a",src2="b",src3="c"}, "foo", ",", "src1",
## `label_replace()`
For each timeseries in `v`, `label_replace(v instant-vector, dst_label string,
replacement string, src_label string, regex string)` matches the regular
expression `regex` against the label `src_label`. If it matches, then the
timeseries is returned with the label `dst_label` replaced by the expansion of
`replacement`. `$1` is replaced with the first matching subgroup, `$2` with the
second etc. If the regular expression doesn't match then the timeseries is
returned unchanged.
For each timeseries in `v`, `label_replace(v instant-vector, dst_label string, replacement string, src_label string, regex string)`
matches the regular expression `regex` against the value of the label `src_label`. If it
matches, the value of the label `dst_label` in the returned timeseries will be the expansion
of `replacement`, together with the original labels in the input. Capturing groups in the
regular expression can be referenced with `$1`, `$2`, etc. If the regular expression doesn't
match then the timeseries is returned unchanged.
This example will return a vector with each time series having a `foo`
label with the value `a` added to it:
This example will return timeseries with the values `a:c` at label `service` and `a` at label `foo`:
```
label_replace(up{job="api-server",service="a:c"}, "foo", "$1", "service", "(.*):.*")