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668 lines
13 KiB
668 lines
13 KiB
---
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title: Template functions
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weight: 30
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---
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# Template functions
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The [text template](https://golang.org/pkg/text/template) format used in `| line_format` and `| label_format` support the usage of functions.
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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:
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```template
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{{ .path }}
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```
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Additionally you can also access the log line using the [`__line__`](#__line__) function.
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You can take advantage of [pipeline](https://golang.org/pkg/text/template/#hdr-Pipelines) to join together multiple functions.
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In a chained pipeline, the result of each command is passed as the last argument of the following command.
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Example:
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```template
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{{ .path | replace " " "_" | trunc 5 | upper }}
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```
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## __line__
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This function returns the current log line.
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Signature:
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`line() string`
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Examples:
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```template
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"{{ __line__ | lower }}"
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`{{ __line__ }}`
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```
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## ToLower and ToUpper
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This function converts the entire string to lowercase or uppercase.
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Signatures:
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- `ToLower(string) string`
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- `ToUpper(string) string`
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Examples:
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```template
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"{{.request_method | ToLower}}"
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"{{.request_method | ToUpper}}"
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`{{ToUpper "This is a string" | ToLower}}`
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```
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> **Note:** In Grafana Loki 2.1 you can also use respectively [`lower`](#lower) and [`upper`](#upper) shortcut, e.g `{{.request_method | lower }}`.
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## Replace string
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> **Note:** In Loki 2.1 [`replace`](#replace) (as opposed to `Replace`) is available with a different signature but easier to chain within pipeline.
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Use this function to perform a simple string replacement.
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Signature:
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`Replace(s, old, new string, n int) string`
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It takes four arguments:
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- `s` source string
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- `old` string to replace
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- `new` string to replace with
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- `n` the maximun amount of replacement (-1 for all)
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Example:
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```template
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`{{ Replace "This is a string" " " "-" -1 }}`
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```
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The results in `This-is-a-string`.
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## Trim, TrimLeft, TrimRight, and TrimSpace
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> **Note:** In Loki 2.1 [trim](#trim), [trimAll](#trimall), [trimSuffix](#trimsuffix) and [trimPrefix](#trimprefix) have been added with a different signature for better pipeline chaining.
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`Trim` returns a slice of the string s with all leading and
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trailing Unicode code points contained in cutset removed.
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Signature: `Trim(value, cutset string) string`
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`TrimLeft` and `TrimRight` are the same as `Trim` except that it trims only leading and trailing characters respectively.
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```template
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`{{ Trim .query ",. " }}`
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`{{ TrimLeft .uri ":" }}`
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`{{ TrimRight .path "/" }}`
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```
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`TrimSpace` TrimSpace returns string s with all leading
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and trailing white space removed, as defined by Unicode.
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Signature: `TrimSpace(value string) string`
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```template
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{{ TrimSpace .latency }}
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```
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`TrimPrefix` and `TrimSuffix` will trim respectively the prefix or suffix supplied.
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Signature:
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- `TrimPrefix(value string, prefix string) string`
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- `TrimSuffix(value string, suffix string) string`
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```template
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{{ TrimPrefix .path "/" }}
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```
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## regexReplaceAll and regexReplaceAllLiteral
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`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 $1 represents the text of the first sub-match. See the golang [Regexp.replaceAll documentation](https://golang.org/pkg/regexp/#Regexp.ReplaceAll) for more examples.
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```template
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`{{ regexReplaceAll "(a*)bc" .some_label "${1}a" }}`
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```
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`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.
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```template
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`{{ regexReplaceAllLiteral "(ts=)" .timestamp "timestamp=" }}`
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```
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You can combine multiple functions using pipe. For example, to strip out spaces and make the request method in capital, you would write the following template: `{{ .request_method | TrimSpace | ToUpper }}`.
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## lower
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> Added in Loki 2.1
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Use this function to convert to lower case.
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Signature:
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`lower(string) string`
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Examples:
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```template
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"{{ .request_method | lower }}"
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`{{ lower "HELLO"}}`
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```
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The last example will return `hello`.
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## upper
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> Added in Loki 2.1
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Use this function to convert to upper case.
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Signature:
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`upper(string) string`
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Examples:
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```template
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"{{ .request_method | upper }}"
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`{{ upper "hello"}}`
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```
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This results in `HELLO`.
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## title
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> **Note:** Added in Loki 2.1.
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Convert to title case.
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Signature:
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`title(string) string`
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Examples:
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```template
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"{{.request_method | title}}"
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`{{ title "hello world"}}`
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```
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The last example will return `Hello World`.
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## trunc
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> **Note:** Added in Loki 2.1.
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Truncate a string and add no suffix.
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Signature:
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`trunc(count int,value string) string`
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Examples:
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```template
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"{{ .path | trunc 2 }}"
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`{{ trunc 5 "hello world"}}` // output: hello
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`{{ trunc -5 "hello world"}}` // output: world
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```
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## substr
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> **Note:** Added in Loki 2.1.
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Get a substring from a string.
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Signature:
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`trunc(start int,end int,value string) string`
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If start is < 0, this calls value[:end].
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If start is >= 0 and end < 0 or end bigger than s length, this calls value[start:]
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Otherwise, this calls value[start, end].
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Examples:
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```template
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"{{ .path | substr 2 5 }}"
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`{{ substr 0 5 "hello world"}}` // output: hello
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`{{ substr 6 11 "hello world"}}` // output: world
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```
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## replace
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> **Note:** Added in Loki 2.1.
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This function performs simple string replacement.
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Signature: `replace(old string, new string, src string) string`
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It takes three arguments:
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- `old` string to replace
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- `new` string to replace with
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- `src` source string
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Examples:
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```template
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{{ .cluster | replace "-cluster" "" }}
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{{ replace "hello" "world" "hello world" }}
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```
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The last example will return `world world`.
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## trim
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> **Note:** Added in Loki 2.1.
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The trim function removes space from either side of a string.
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Signature: `trim(string) string`
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Examples:
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```template
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{{ .ip | trim }}
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{{ trim " hello " }} // output: hello
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```
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## trimAll
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> **Note:** Added in Loki 2.1.
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Use this function to remove given characters from the front or back of a string.
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Signature: `trimAll(chars string,src string) string`
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Examples:
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```template
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{{ .path | trimAll "/" }}
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{{ trimAll "$" "$5.00" }} // output: 5.00
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```
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## trimSuffix
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> **Note:** Added in Loki 2.1.
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Use this function to trim just the suffix from a string.
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Signature: `trimSuffix(suffix string, src string) string`
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Examples:
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```template
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{{ .path | trimSuffix "/" }}
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{{ trimSuffix "-" "hello-" }} // output: hello
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```
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## trimPrefix
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> **Note:** Added in Loki 2.1.
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Use this function to trim just the prefix from a string.
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Signature: `trimPrefix(suffix string, src string) string`
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Examples:
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```template
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{{ .path | trimPrefix "/" }}
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{{ trimPrefix "-" "-hello" }} // output: hello
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```
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## indent
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> **Note:** Added in Loki 2.1.
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The indent function indents every line in a given string to the specified indent width. This is useful when aligning multi-line strings.
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Signature: `indent(spaces int,src string) string`
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```template
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{{ indent 4 .query }}
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```
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This indents each line contained in the `.query` by four (4) spaces.
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## nindent
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> **Note:** Added in Loki 2.1.
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The nindent function is the same as the indent function, but prepends a new line to the beginning of the string.
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Signature: `nindent(spaces int,src string) string`
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```template
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{{ nindent 4 .query }}
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```
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This will indent every line of text by 4 space characters and add a new line to the beginning.
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## repeat
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> **Note:** Added in Loki 2.1.
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Use this function to repeat a string multiple times.
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Signature: `repeat(c int,value string) string`
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```template
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{{ repeat 3 "hello" }} // output: hellohellohello
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```
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## contains
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> **Note:** Added in Loki 2.1.
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Use this function to test to see if one string is contained inside of another.
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Signature: `contains(s string, src string) bool`
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Examples:
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```template
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{{ if .err contains "ErrTimeout" }} timeout {{end}}
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{{ if contains "he" "hello" }} yes {{end}}
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```
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## hasPrefix and hasSuffix
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> **Note:** Added in Loki 2.1.
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The `hasPrefix` and `hasSuffix` functions test whether a string has a given prefix or suffix.
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Signatures:
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- `hasPrefix(prefix string, src string) bool`
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- `hasSuffix(suffix string, src string) bool`
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Examples:
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```template
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{{ if .err hasSuffix "Timeout" }} timeout {{end}}
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{{ if hasPrefix "he" "hello" }} yes {{end}}
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```
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## add
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> **Note:** Added in Loki 2.3.
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Sum numbers. Supports multiple numbers
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Signature: `func(i ...interface{}) int64`
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```template
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{{ add 3 2 5 }} // output: 10
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```
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## sub
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> **Note:** Added in Loki 2.3.
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Subtract numbers.
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Signature: `func(a, b interface{}) int64`
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```template
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{{ sub 5 2 }} // output: 3
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```
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## mul
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> **Note:** Added in Loki 2.3.
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Mulitply numbers. Supports multiple numbers.
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Signature: `func(a interface{}, v ...interface{}) int64`
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```template
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{{ mul 5 2 3}} // output: 30
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```
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## div
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> **Note:** Added in Loki 2.3.
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Integer divide numbers.
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Signature: `func(a, b interface{}) int64`
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```template
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{{ div 10 2}} // output: 5
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```
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## addf
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> **Note:** Added in Loki 2.3.
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Sum numbers. Supports multiple numbers.
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Signature: `func(i ...interface{}) float64`
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```template
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{{ addf 3.5 2 5 }} // output: 10.5
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```
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## subf
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> **Note:** Added in Loki 2.3.
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Subtract numbers. Supports multiple numbers.
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Signature: `func(a interface{}, v ...interface{}) float64`
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```template
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{{ subf 5.5 2 1.5 }} // output: 2
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```
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## mulf
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> **Note:** Added in Loki 2.3.
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Mulitply numbers. Supports multiple numbers
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Signature: `func(a interface{}, v ...interface{}) float64`
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```template
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{{ mulf 5.5 2 2.5 }} // output: 27.5
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```
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## divf
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> **Note:** Added in Loki 2.3.
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Divide numbers. Supports multiple numbers.
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Signature: `func(a interface{}, v ...interface{}) float64`
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```template
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{{ divf 10 2 4}} // output: 1.25
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```
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## mod
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> **Note:** Added in Loki 2.3.
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Modulo wit mod.
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Signature: `func(a, b interface{}) int64`
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```template
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{{ mod 10 3}} // output: 1
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```
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## max
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> **Note:** Added in Loki 2.3.
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Return the largest of a series of integers:
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Signature: `max(a interface{}, i ...interface{}) int64`
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```template
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{{ max 1 2 3 }} //output 3
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```
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## min
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> **Note:** Added in Loki 2.3.
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Return the smallest of a series of integers.
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Signature: `min(a interface{}, i ...interface{}) int64`
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```template
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{{ max 1 2 3 }} //output 1
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```
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## maxf
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> **Note:** Added in Loki 2.3.
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Return the largest of a series of floats:
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Signature: `maxf(a interface{}, i ...interface{}) float64`
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```template
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{{ maxf 1 2.5 3 }} //output 3
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```
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## minf
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> **Note:** Added in Loki 2.3.
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Return the smallest of a series of floats.
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Signature: `minf(a interface{}, i ...interface{}) float64`
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```template
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{{ minf 1 2.5 3 }} //output 1.5
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```
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## ceil
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> **Note:** Added in Loki 2.3.
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Returns the greatest float value greater than or equal to input value
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Signature: `ceil(a interface{}) float64`
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```template
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{{ ceil 123.001 }} //output 124.0
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```
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## floor
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> **Note:** Added in Loki 2.3.
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Returns the greatest float value less than or equal to input value
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Signature: `floor(a interface{}) float64`
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```template
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{{ floor 123.9999 }} //output 123.0
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```
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## round
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> **Note:** Added in Loki 2.3.
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Returns a float value with the remainder rounded to the given number of digits after the decimal point.
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Signature: `round(a interface{}, p int, rOpt ...float64) float64`
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```template
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{{ round 123.555555 3 }} //output 123.556
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```
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We can also provide a `roundOn` number as third parameter
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```template
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{{ round 123.88571428571 5 .2 }} //output 123.88572
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```
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With default `roundOn` of `.5` the above value would be `123.88571`
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## int
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> **Note:** Added in Loki 2.3.
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Convert value to an int.
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Signature: `toInt(v interface{}) int`
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```template
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{{ "3" | int }} //output 3
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```
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## float64
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> **Note:** Added in Loki 2.3.
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Convert to a float64.
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Signature: `toFloat64(v interface{}) float64`
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```template
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{{ "3.5" | float64 }} //output 3.5
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```
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## fromJson
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> **Note:** Added in Loki 2.3.
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fromJson decodes a JSON document into a structure. If the input cannot be decoded as JSON the function will return an empty string.
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```template
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fromJson "{\"foo\": 55}"
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```
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Example of a query to print a newline per queries stored as a json array in the log line:
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```logql
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{job="cortex/querier"} |= "finish in prometheus" | logfmt | line_format "{{ range $q := fromJson .queries }} {{ $q.query }} {{ end }}"
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```
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## now
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`now` returns the current local time.
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```template
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{{ now }}
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```
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## toDate
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`toDate` parses a formatted string and returns the time value it represents.
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```template
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{{ toDate "2006-01-02" "2021-11-02" }}
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```
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## date
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`date` returns a textual representation of the time value formatted according to the provided [golang datetime layout](https://pkg.go.dev/time#pkg-constants).
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```template
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{ date "2006-01-02" now }}
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```
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## unixEpoch
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`unixEpoch` returns the number of seconds elapsed since January 1, 1970 UTC.
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```template
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{ unixEpoch now }}
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```
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Example of a query to filter cortex querier jobs which create time is 1 day before:
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```logql
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{job="cortex/querier"} | label_format nowEpoch=`{{(unixEpoch now)}}`,createDateEpoch=`{{unixEpoch (toDate "2006-01-02" .createDate)}}` | label_format dateTimeDiff="{{sub .nowEpoch .createDateEpoch}}" | dateTimeDiff > 86400
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```
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