loki/docs/sources/query/template_functions.md

---
title: Template functions
menuTItle:  
description: Describes functions that are supported by the text template.
aliases: 
- /docs/loki/latest/logql
- /docs/loki/latest/query
weight: 30
---

# Template functions

The [text template](https://golang.org/pkg/text/template) format used in `| line_format` and `| label_format` support the usage of functions.

All labels are added as variables in the template engine. They can be referenced using they label name prefixed by a `.`(e.g `.label_name`). For example the following template will output the value of the path label:

```template
{{ .path }}
```

Additionally you can also access the log line using the [`__line__`](#__line__) function and the timestamp using the [`__timestamp__`](#__timestamp__) function.

You can take advantage of [pipeline](https://golang.org/pkg/text/template/#hdr-Pipelines) to join together multiple functions.
In a chained pipeline, the result of each command is passed as the last argument of the following command.

Example:

```template
{{ .path | replace " " "_" | trunc 5 | upper }}
```

For function that returns a `bool` such as `contains`, `eq`, `hasPrefix` and `hasSuffix`, you can apply `AND` / `OR` and nested `if` logic.

Example:

```template
{{ if and (contains "he" "hello") (contains "llo" "hello") }} yes {{end}}
{{ if or (contains "he" "hello") (contains("llo" "hello") }} yes {{end}}
{{ if contains .err "ErrTimeout" }} timeout {{else if contains "he" "hello"}} yes {{else}} no {{end}}
```

## __line__

This function returns the current log line.

Signature: `line() string`

Examples:

```template
"{{ __line__ | lower }}"
`{{ __line__ }}`
```

## __timestamp__

This function returns the current log lines timestamp.

Signature: `timestamp() time.Time`

```template
"{{ __timestamp__ }}"
`{{ __timestamp__ | date "2006-01-02T15:04:05.00Z-07:00" }}`
`{{ __timestamp__ | unixEpoch }}`
```

See the blog: [Parsing and formatting date/time in Go](https://www.pauladamsmith.com/blog/2011/05/go_time.html) for more information.

## regexReplaceAll and regexReplaceAllLiteral

`regexReplaceAll` returns a copy of the input string, replacing matches of the Regexp with the replacement string replacement. Inside string replacement, $ signs are interpreted as in Expand, so for instance $1 represents the text of the first sub-match. See the golang [Regexp.replaceAll documentation](https://golang.org/pkg/regexp/#Regexp.ReplaceAll) for more examples.

Example:

```template
`{{ regexReplaceAll "(a*)bc" .some_label "${1}a" }}`
```

`regexReplaceAllLiteral` function returns a copy of the input string and replaces matches of the Regexp with the replacement string replacement. The replacement string is substituted directly, without using Expand.

Example:

```template
`{{ regexReplaceAllLiteral "(ts=)" .timestamp "timestamp=" }}`
```

## lower

Use this function to convert to lower case.

Signature: `lower(string) string`

Examples:

```template
"{{ .request_method | lower }}"
`{{ lower  "HELLO"}}`
```

The last example will return `hello`.

## upper

Use this function to convert to upper case.

Signature: `upper(string) string`

Examples:

```template
"{{ .request_method | upper }}"
`{{ upper  "hello"}}`
```

This results in `HELLO`.

## title

Convert to title case.

Signature: `title(string) string`

Examples:

```template
"{{.request_method | title}}"
`{{ title "hello world"}}`
```

The last example will return `Hello World`.

## trunc

Truncate a string and add no suffix.

Signature: `trunc(count int,value string) string`

Examples:

```template
"{{ .path | trunc 2 }}"
`{{ trunc 5 "hello world"}}`   // output: hello
`{{ trunc -5 "hello world"}}`  // output: world
```

## substr

Get a substring from a string.

Signature: `substr(start int,end int,value string) string`

If start is < 0, this calls value[:end].
If start is >= 0 and end < 0 or end bigger than s length, this calls value[start:]
Otherwise, this calls value[start, end].

Examples:

```template
"{{ .path | substr 2 5 }}"
`{{ substr 0 5 "hello world"}}`  // output: hello
`{{ substr 6 11 "hello world"}}` // output: world
```

## replace

This function performs simple string replacement.

Signature: `replace(old string, new string, src string) string`

It takes three arguments:

- `old` string to replace
- `new` string to replace with
- `src` source string

Examples:

```template
{{ .cluster | replace "-cluster" "" }}
{{ replace "hello" "world" "hello world" }}
```

The last example will return `world world`.

## trim

The trim function removes space from either side of a string.

Signature: `trim(string) string`

Examples:

```template
{{ .ip | trim }}
{{ trim "   hello    " }} // output: hello
```

## trimAll

Use this function to remove given characters from the front or back of a string.

Signature: `trimAll(chars string,src string) string`

Examples:

```template
{{ .path | trimAll "/" }}
{{ trimAll "$" "$5.00" }} // output: 5.00
```

## trimSuffix

Use this function to trim just the suffix from a string.

Signature: `trimSuffix(suffix string, src string) string`

Examples:

```template
{{  .path | trimSuffix "/" }}
{{ trimSuffix "-" "hello-" }} // output: hello
```

## trimPrefix

Use this function to trim just the prefix from a string.

Signature: `trimPrefix(prefix string, src string) string`

Examples:

```template
{{  .path | trimPrefix "/" }}
{{ trimPrefix "-" "-hello" }} // output: hello
```

## alignLeft

Use this function to format a string to a fixed with, aligning the content to the left.

Signature: `alignLeft(count int, src string) string`

Examples:

```template
`{{ alignLeft 5 "hello world"}}` // output: "hello"
`{{ alignLeft 5 "hi"}}`          // output: "hi   "
```

## alignRight

Use this function to format a string to a fixed with, aligning the content to the right.

Signature: `alignRight(count int, src string) string`

Examples:

```template
`{{ alignRight 5 "hello world"}}` // output: "world"
`{{ alignRight 5 "hi"}}`          // output: "   hi"
```

## indent

The indent function indents every line in a given string to the specified indent width. This is useful when aligning multi-line strings.

Signature: `indent(spaces int,src string) string`

Example:

```template
{{ indent 4 .query }}
```

This indents each line contained in the `.query` by four (4) spaces.

## nindent

The nindent function is the same as the indent function, but prepends a new line to the beginning of the string.

Signature: `nindent(spaces int,src string) string`

Example:

```template
{{ nindent 4 .query }}
```

This will indent every line of text by 4 space characters and add a new line to the beginning.

## repeat

Use this function to repeat a string multiple times.

Signature: `repeat(c int,value string) string`

Example:

```template
{{ repeat 3 "hello" }} // output: hellohellohello
```

## contains

Use this function to test to see if one string is contained inside of another.

Signature: `contains(s string, src string) bool`

Examples:

```template
{{ if contains .err "ErrTimeout" }} timeout {{end}}
{{ if contains "he" "hello" }} yes {{end}}
```

## eq

Use this function to test to see if one string has exact matching inside of another.

Signature: `eq(s string, src string) bool`

Examples:

```template
{{ if eq .err "ErrTimeout" }} timeout {{end}}
{{ if eq "he" "hello" }} yes {{end}}
```

## hasPrefix and hasSuffix

The `hasPrefix` and `hasSuffix` functions test whether a string has a given prefix or suffix.

Signatures:

- `hasPrefix(prefix string, src string) bool`
- `hasSuffix(suffix string, src string) bool`

Examples:

```template
{{ if hasSuffix .err "Timeout" }} timeout {{end}}
{{ if hasPrefix "he" "hello" }} yes {{end}}
```

## add

Sum numbers. Supports multiple numbers

Signature: `func(i ...interface{}) int64`

Example:

```template
{{ add 3 2 5 }} // output: 10
```

## sub

Subtract numbers.

Signature: `func(a, b interface{}) int64`

Example:

```template
{{ sub 5 2 }} // output: 3
```

## mul

Mulitply numbers. Supports multiple numbers.

Signature: `func(a interface{}, v ...interface{}) int64`

Example:

```template
{{ mul 5 2 3}} // output: 30
```

## div

Integer divide numbers.

Signature: `func(a, b interface{}) int64`

Example:

```template
{{ div 10 2}} // output: 5
```

## addf

Sum numbers. Supports multiple numbers.

Signature: `func(i ...interface{}) float64`

Example:

```template
{{ addf 3.5 2 5 }} // output: 10.5
```

## subf

Subtract numbers. Supports multiple numbers.

Signature: `func(a interface{}, v ...interface{}) float64`

Example:

```template
{{ subf  5.5 2 1.5 }} // output: 2
```

## mulf

Mulitply numbers. Supports multiple numbers

Signature: `func(a interface{}, v ...interface{}) float64`

Example:

```template
{{ mulf 5.5 2 2.5 }} // output: 27.5
```

## divf

Divide numbers. Supports multiple numbers.

Signature: `func(a interface{}, v ...interface{}) float64`

Example:

```template
{{ divf 10 2 4}} // output: 1.25
```

## mod

Modulo wit mod.

Signature: `func(a, b interface{}) int64`

Example:

```template
{{ mod 10 3}} // output: 1
```

## max

Return the largest of a series of integers:

Signature: `max(a interface{}, i ...interface{}) int64`

Example:

```template
{{ max 1 2 3 }} //output 3
```

## min

Return the smallest of a series of integers.

Signature: `min(a interface{}, i ...interface{}) int64`

Example:

```template
{{ max 1 2 3 }} //output 1
```

## maxf

Return the largest of a series of floats:

Signature: `maxf(a interface{}, i ...interface{}) float64`

Example:

```template
{{ maxf 1 2.5 3 }} //output 3
```

## minf

Return the smallest of a series of floats.

Signature: `minf(a interface{}, i ...interface{}) float64`

Example:

```template
{{ minf 1 2.5 3 }} //output 1.5
```

## ceil

Returns the greatest float value greater than or equal to input value

Signature: `ceil(a interface{}) float64`

Example:

```template
{{ ceil 123.001 }} //output 124.0
```

## floor

Returns the greatest float value less than or equal to input value

Signature: `floor(a interface{}) float64`

Example:

```template
{{ floor 123.9999 }} //output 123.0
```

## round

Returns a float value with the remainder rounded to the given number of digits after the decimal point.

Signature: `round(a interface{}, p int, rOpt ...float64) float64`

Example:

```template
{{ round 123.555555 3 }} //output 123.556
```

We can also provide a `roundOn` number as third parameter

Example:

```template
{{ round 123.88571428571 5 .2 }} //output 123.88572
```

With default `roundOn` of `.5` the above value would be `123.88571`

## int

Convert value to an int.

Signature: `toInt(v interface{}) int`

Example:

```template
{{ "3" | int }} //output 3
```

## float64

Convert to a float64.

Signature: `toFloat64(v interface{}) float64`

Example:

```template
{{ "3.5" | float64 }} //output 3.5
```

## fromJson

Decodes a JSON document into a structure. If the input cannot be decoded as JSON the function will return an empty string.

Signature: `fromJson(v string) interface{}`

Example:

```template
fromJson "{\"foo\": 55}"
```

Example of a query to print a newline per queries stored as a json array in the log line:

```logql
{job="loki/querier"} |= "finish in prometheus" | logfmt | line_format "{{ range $q := fromJson .queries }} {{ $q.query }} {{ end }}"
```

## now

Returns the current time in the local timezone of the Loki server.

Signature: `Now() time.Time`

Example:

```template
{{ now }}
```

## toDate

Parses a formatted string and returns the time value it represents using the local timezone of the server running Loki.

For more consistency between Loki installations, it's recommended to use `toDateInZone`

The format string must use the exact date as defined in the [golang datetime layout](https://pkg.go.dev/time#pkg-constants)

Signature: `toDate(fmt, str string) time.Time`

Examples: 

```template
{{ toDate "2006-01-02" "2021-11-02" }}
{{ .foo | toDate "2006-01-02T15:04:05.999999999Z" }}
```

## toDateInZone

Parses a formatted string and returns the time value it represents in the provided timezone.

The format string must use the exact date as defined in the [golang datetime layout](https://pkg.go.dev/time#pkg-constants)

The timezone value can be `Local`, `UTC`, or any of the IANA Time Zone database values

Signature: `toDateInZone(fmt, zone, str string) time.Time`

Examples:

```template
{{ toDateInZone "2006-01-02" "UTC" "2021-11-02" }}
{{ .foo | toDateInZone "2006-01-02T15:04:05.999999999Z" "UTC" }}
```

## date

Returns a textual representation of the time value formatted according to the provided [golang datetime layout](https://pkg.go.dev/time#pkg-constants).

Signature: `date(fmt string, date interface{}) string`

Example:

```template
{{ date "2006-01-02" now }}
```

## unixEpoch

Returns the number of seconds elapsed since January 1, 1970 UTC.

Signature: `unixEpoch(date time.Time) string`

Examples:

```template
{{ unixEpoch now }}
{{ .foo | toDateInZone "2006-01-02T15:04:05.999999999Z" "UTC" | unixEpoch }}
```

Example of a query to filter Loki querier jobs which create time is 1 day before:
```logql
{job="loki/querier"} | label_format nowEpoch=`{{(unixEpoch now)}}`,createDateEpoch=`{{unixEpoch (toDate "2006-01-02" .createDate)}}` | label_format dateTimeDiff="{{sub .nowEpoch .createDateEpoch}}" | dateTimeDiff > 86400
```

## unixEpochMillis

Returns the number of milliseconds elapsed since January 1, 1970 UTC.

Signature: `unixEpochMillis(date time.Time) string`

Examples:

```template
{{ unixEpochMillis now }}
{{ .foo | toDateInZone "2006-01-02T15:04:05.999999999Z" "UTC" | unixEpochMillis }}
```

## unixEpochNanos

Returns the number of nanoseconds elapsed since January 1, 1970 UTC.

Signature: `unixEpochNanos(date time.Time) string`

Examples:

```template
{{ unixEpochNanos now }}
{{ .foo | toDateInZone "2006-01-02T15:04:05.999999999Z" "UTC" | unixEpochNanos }}
```

## unixToTime

Converts the string epoch to the time value it represents. Epoch times in days, seconds, milliseconds, microseconds and nanoseconds are supported.

Signature: `unixToTime(epoch string) time.Time`

Examples:

Consider the following log line `{"from": "1679577215","to":"1679587215","message":"some message"}`. To print the `from` field as human readable add the following at the end of the LogQL query:
```logql
... | json | line_format `from="{{date "2006-01-02" (unixToTime .from)}}"`
```

## default

Checks whether the string(`src`) is set, and returns default(`d`) if not set.

Signature: `default(d string, src string) string`

Examples:

```template
{{ default "-" "" }} // output: -
{{ default "" "foo" }} // output: foo
```

Example of a query to print a `-` if the `http_request_headers_x_forwarded_for` label is empty:
```logql
{job="access_log"} | json | line_format `{{.http_request_headers_x_forwarded_for | default "-"}}`
```

## count

Counts occurrences of the regex (`regex`) in (`src`).

Signature: `count(regex string, src string) int`

Examples:

```template
{{ count "a|b" "abab" }} // output: 4
{{ count "o" "foo" }}    // output: 2
```

Example of a query to print how many times XYZ occurs in a line:
```logql
{job="xyzlog"} | line_format `{{ __line__ | count "XYZ"}}`
```

## urlencode

Use this function to [urlencode](https://en.wikipedia.org/wiki/URL_encoding) a string.

Signature: `urlencode(string) string`

Examples:

```template
"{{ .request_url | urlencode }}"
`{{ urlencode  .request_url}}`
```

## urldecode

Use this function to [urldecode](https://en.wikipedia.org/wiki/URL_encoding) a string.

Signature: `urldecode(string) string`

Examples:

```template
"{{ .request_url | urldecode }}"
`{{ urldecode  .request_url}}`
```

## b64enc

Base64 encode a string.

Signature: `b64enc(string) string`

Examples:

```template
"{{ .foo | b64enc }}"
`{{ b64enc  .foo }}`
```

## b64dec

Base64 decode a string.

Signature: `b64dec(string) string`

Examples:

```template
"{{ .foo | b64dec }}"
`{{ b64dec  .foo }}`
```

## bytes

Convert a humanized byte string to bytes using [go-humanize](https://pkg.go.dev/github.com/dustin/go-humanize#ParseBytes)

Signature: `bytes(string) string`

Examples:

```template
"{{ .foo | bytes }}"
`{{ bytes .foo }}`
```

## duration

An alias for `duration_seconds`

Examples:

```template
"{{ .foo | duration }}"
`{{ duration .foo }}`
```

## duration_seconds

Convert a humanized time duration to seconds using [time.ParseDuration](https://pkg.go.dev/time#ParseDuration)

Signature: `duration_seconds(string) float64`

Examples:

```template
"{{ .foo | duration_seconds }}"
`{{ duration_seconds .foo }}`
```