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template.go
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template.go
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// Copyright 2013 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package templates
import (
"errors"
"fmt"
htmlTpl "html/template"
"io"
"math"
"net"
"net/url"
"regexp"
"sort"
"strconv"
"strings"
"sync"
textTpl "text/template"
"time"
"github.com/bmatcuk/doublestar/v4"
"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/formatutil"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/promutils"
)
// go template execution fails when it's tree is empty
const defaultTemplate = `{{- define "default.template" -}}{{- end -}}`
var tplMu sync.RWMutex
type textTemplate struct {
current *textTpl.Template
replacement *textTpl.Template
}
var masterTmpl textTemplate
func newTemplate() *textTpl.Template {
tmpl := textTpl.New("").Option("missingkey=zero").Funcs(templateFuncs())
return textTpl.Must(tmpl.Parse(defaultTemplate))
}
// Load func loads templates from multiple globs specified in pathPatterns and either
// sets them directly to current template if it's undefined or with overwrite=true
// or sets replacement templates and adds templates with new names to a current
func Load(pathPatterns []string, overwrite bool) error {
var err error
tmpl := newTemplate()
for _, tp := range pathPatterns {
p, err := doublestar.FilepathGlob(tp)
if err != nil {
return fmt.Errorf("failed to retrieve a template glob %q: %w", tp, err)
}
if len(p) > 0 {
tmpl, err = tmpl.ParseFiles(p...)
if err != nil {
return fmt.Errorf("failed to parse template glob %q: %w", tp, err)
}
}
}
if len(tmpl.Templates()) > 0 {
err := tmpl.Execute(io.Discard, nil)
if err != nil {
return fmt.Errorf("failed to execute template: %w", err)
}
}
tplMu.Lock()
defer tplMu.Unlock()
if masterTmpl.current == nil || overwrite {
masterTmpl.replacement = nil
masterTmpl.current = newTemplate()
} else {
masterTmpl.replacement = newTemplate()
if err = copyTemplates(tmpl, masterTmpl.replacement, overwrite); err != nil {
return err
}
}
return copyTemplates(tmpl, masterTmpl.current, overwrite)
}
func copyTemplates(from *textTpl.Template, to *textTpl.Template, overwrite bool) error {
if from == nil {
return nil
}
if to == nil {
to = newTemplate()
}
tmpl, err := from.Clone()
if err != nil {
return err
}
for _, t := range tmpl.Templates() {
if to.Lookup(t.Name()) == nil || overwrite {
to, err = to.AddParseTree(t.Name(), t.Tree)
if err != nil {
return fmt.Errorf("failed to add template %q: %w", t.Name(), err)
}
}
}
return nil
}
// Reload func replaces current template with a replacement template
// which was set by Load with override=false
func Reload() {
tplMu.Lock()
defer tplMu.Unlock()
if masterTmpl.replacement != nil {
masterTmpl.current = masterTmpl.replacement
masterTmpl.replacement = nil
}
}
// metric is private copy of datasource.Metric,
// it is used for templating annotations,
// Labels as map simplifies templates evaluation.
type metric struct {
Labels map[string]string
Timestamp int64
Value float64
}
// datasourceMetricsToTemplateMetrics converts Metrics from datasource package to private copy for templating.
func datasourceMetricsToTemplateMetrics(ms []datasource.Metric) []metric {
mss := make([]metric, 0, len(ms))
for _, m := range ms {
labelsMap := make(map[string]string, len(m.Labels))
for _, labelValue := range m.Labels {
labelsMap[labelValue.Name] = labelValue.Value
}
mss = append(mss, metric{
Labels: labelsMap,
Timestamp: m.Timestamps[0],
Value: m.Values[0]})
}
return mss
}
// QueryFn is used to wrap a call to datasource into simple-to-use function
// for templating functions.
type QueryFn func(query string) ([]datasource.Metric, error)
// UpdateWithFuncs updates existing or sets a new function map for a template
func UpdateWithFuncs(funcs textTpl.FuncMap) {
tplMu.Lock()
defer tplMu.Unlock()
masterTmpl.current = masterTmpl.current.Funcs(funcs)
}
// GetWithFuncs returns a copy of current template with additional FuncMap
// provided with funcs argument
func GetWithFuncs(funcs textTpl.FuncMap) (*textTpl.Template, error) {
tplMu.RLock()
defer tplMu.RUnlock()
tmpl, err := masterTmpl.current.Clone()
if err != nil {
return nil, err
}
return tmpl.Funcs(funcs), nil
}
// Get returns a copy of a template
func Get() (*textTpl.Template, error) {
tplMu.RLock()
defer tplMu.RUnlock()
return masterTmpl.current.Clone()
}
// FuncsWithQuery returns a function map that depends on metric data
func FuncsWithQuery(query QueryFn) textTpl.FuncMap {
return textTpl.FuncMap{
"query": func(q string) ([]metric, error) {
if query == nil {
return nil, fmt.Errorf("cannot execute query %q: query is not available in this context", q)
}
result, err := query(q)
if err != nil {
return nil, err
}
return datasourceMetricsToTemplateMetrics(result), nil
},
}
}
// FuncsWithExternalURL returns a function map that depends on externalURL value
func FuncsWithExternalURL(externalURL *url.URL) textTpl.FuncMap {
return textTpl.FuncMap{
"externalURL": func() string {
return externalURL.String()
},
"pathPrefix": func() string {
return externalURL.Path
},
}
}
// templateFuncs initiates template helper functions
func templateFuncs() textTpl.FuncMap {
// See https://prometheus.io/docs/prometheus/latest/configuration/template_reference/
// and https://github.com/prometheus/prometheus/blob/fa6e05903fd3ce52e374a6e1bf4eb98c9f1f45a7/template/template.go#L150
return textTpl.FuncMap{
/* Strings */
// title returns a copy of the string s with all Unicode letters
// that begin words mapped to their Unicode title case.
// alias for https://golang.org/pkg/strings/#Title
"title": strings.Title,
// toUpper returns s with all Unicode letters mapped to their upper case.
// alias for https://golang.org/pkg/strings/#ToUpper
"toUpper": strings.ToUpper,
// toLower returns s with all Unicode letters mapped to their lower case.
// alias for https://golang.org/pkg/strings/#ToLower
"toLower": strings.ToLower,
// crlfEscape replaces '\n' and '\r' chars with `\\n` and `\\r`.
// This function is deprecated.
//
// It is better to use quotesEscape, jsonEscape, queryEscape or pathEscape instead -
// these functions properly escape `\n` and `\r` chars according to their purpose.
"crlfEscape": func(q string) string {
q = strings.Replace(q, "\n", `\n`, -1)
return strings.Replace(q, "\r", `\r`, -1)
},
// quotesEscape escapes the string, so it can be safely put inside JSON string.
//
// See also jsonEscape.
"quotesEscape": quotesEscape,
// jsonEscape converts the string to properly encoded JSON string.
//
// See also quotesEscape.
"jsonEscape": jsonEscape,
// htmlEscape applies html-escaping to q, so it can be safely embedded as plaintext into html.
//
// See also safeHtml.
"htmlEscape": htmlEscape,
// stripPort splits string into host and port, then returns only host.
"stripPort": func(hostPort string) string {
host, _, err := net.SplitHostPort(hostPort)
if err != nil {
return hostPort
}
return host
},
// stripDomain removes the domain part of a FQDN. Leaves port untouched.
"stripDomain": func(hostPort string) string {
host, port, err := net.SplitHostPort(hostPort)
if err != nil {
host = hostPort
}
ip := net.ParseIP(host)
if ip != nil {
return hostPort
}
host = strings.Split(host, ".")[0]
if port != "" {
return net.JoinHostPort(host, port)
}
return host
},
// match reports whether the string s
// contains any match of the regular expression pattern.
// alias for https://golang.org/pkg/regexp/#MatchString
"match": regexp.MatchString,
// reReplaceAll ReplaceAllString returns a copy of src, replacing matches of the Regexp with
// the replacement string repl. Inside repl, $ signs are interpreted as in Expand,
// so for instance $1 represents the text of the first submatch.
// alias for https://golang.org/pkg/regexp/#Regexp.ReplaceAllString
"reReplaceAll": func(pattern, repl, text string) string {
re := regexp.MustCompile(pattern)
return re.ReplaceAllString(text, repl)
},
// parseDuration parses a duration string such as "1h" into the number of seconds it represents
"parseDuration": func(s string) (float64, error) {
d, err := promutils.ParseDuration(s)
if err != nil {
return 0, err
}
return d.Seconds(), nil
},
// same with parseDuration but returns a time.Duration
"parseDurationTime": func(s string) (time.Duration, error) {
d, err := promutils.ParseDuration(s)
if err != nil {
return 0, err
}
return d, nil
},
/* Numbers */
// humanize converts given number to a human readable format
// by adding metric prefixes https://en.wikipedia.org/wiki/Metric_prefix
"humanize": func(i interface{}) (string, error) {
v, err := toFloat64(i)
if err != nil {
return "", err
}
if v == 0 || math.IsNaN(v) || math.IsInf(v, 0) {
return fmt.Sprintf("%.4g", v), nil
}
if math.Abs(v) >= 1 {
prefix := ""
for _, p := range []string{"k", "M", "G", "T", "P", "E", "Z", "Y"} {
if math.Abs(v) < 1000 {
break
}
prefix = p
v /= 1000
}
return fmt.Sprintf("%.4g%s", v, prefix), nil
}
prefix := ""
for _, p := range []string{"m", "u", "n", "p", "f", "a", "z", "y"} {
if math.Abs(v) >= 1 {
break
}
prefix = p
v *= 1000
}
return fmt.Sprintf("%.4g%s", v, prefix), nil
},
// humanize1024 converts given number to a human readable format with 1024 as base
"humanize1024": func(i interface{}) (string, error) {
v, err := toFloat64(i)
if err != nil {
return "", err
}
if math.Abs(v) <= 1 || math.IsNaN(v) || math.IsInf(v, 0) {
return fmt.Sprintf("%.4g", v), nil
}
return formatutil.HumanizeBytes(v), nil
},
// humanizeDuration converts given seconds to a human-readable duration
"humanizeDuration": func(i interface{}) (string, error) {
v, err := toFloat64(i)
if err != nil {
return "", err
}
if math.IsNaN(v) || math.IsInf(v, 0) {
return fmt.Sprintf("%.4g", v), nil
}
if v == 0 {
return fmt.Sprintf("%.4gs", v), nil
}
if math.Abs(v) >= 1 {
sign := ""
if v < 0 {
sign = "-"
v = -v
}
seconds := int64(v) % 60
minutes := (int64(v) / 60) % 60
hours := (int64(v) / 60 / 60) % 24
days := int64(v) / 60 / 60 / 24
// For days to minutes, we display seconds as an integer.
if days != 0 {
return fmt.Sprintf("%s%dd %dh %dm %ds", sign, days, hours, minutes, seconds), nil
}
if hours != 0 {
return fmt.Sprintf("%s%dh %dm %ds", sign, hours, minutes, seconds), nil
}
if minutes != 0 {
return fmt.Sprintf("%s%dm %ds", sign, minutes, seconds), nil
}
// For seconds, we display 4 significant digits.
return fmt.Sprintf("%s%.4gs", sign, v), nil
}
prefix := ""
for _, p := range []string{"m", "u", "n", "p", "f", "a", "z", "y"} {
if math.Abs(v) >= 1 {
break
}
prefix = p
v *= 1000
}
return fmt.Sprintf("%.4g%ss", v, prefix), nil
},
// humanizePercentage converts given ratio value to a fraction of 100
"humanizePercentage": func(i interface{}) (string, error) {
v, err := toFloat64(i)
if err != nil {
return "", err
}
return fmt.Sprintf("%.4g%%", v*100), nil
},
// humanizeTimestamp converts given timestamp to a human readable time equivalent
"humanizeTimestamp": func(i interface{}) (string, error) {
v, err := toFloat64(i)
if err != nil {
return "", err
}
if math.IsNaN(v) || math.IsInf(v, 0) {
return fmt.Sprintf("%.4g", v), nil
}
t := timeFromUnixTimestamp(v).Time().UTC()
return fmt.Sprint(t), nil
},
// toTime converts given timestamp to a time.Time.
"toTime": func(i interface{}) (time.Time, error) {
v, err := toFloat64(i)
if err != nil {
return time.Time{}, err
}
if math.IsNaN(v) || math.IsInf(v, 0) {
return time.Time{}, fmt.Errorf("cannot convert %v to time.Time", v)
}
t := timeFromUnixTimestamp(v).Time().UTC()
return t, nil
},
/* URLs */
// externalURL returns value of `external.url` flag
"externalURL": func() string {
// externalURL function supposed to be substituted at FuncsWithExteralURL().
// it is present here only for validation purposes, when there is no
// provided datasource.
//
// return non-empty slice to pass validation with chained functions in template
return ""
},
// pathPrefix returns a Path segment from the URL value in `external.url` flag
"pathPrefix": func() string {
// pathPrefix function supposed to be substituted at FuncsWithExteralURL().
// it is present here only for validation purposes, when there is no
// provided datasource.
//
// return non-empty slice to pass validation with chained functions in template
return ""
},
// pathEscape escapes the string so it can be safely placed inside a URL path segment.
//
// See also queryEscape.
"pathEscape": url.PathEscape,
// queryEscape escapes the string so it can be safely placed inside a query arg in URL.
//
// See also queryEscape.
"queryEscape": url.QueryEscape,
// query executes the MetricsQL/PromQL query against
// configured `datasource.url` address.
// For example, {{ query "foo" | first | value }} will
// execute "/api/v1/query?query=foo" request and will return
// the first value in response.
"query": func(q string) ([]metric, error) {
// query function supposed to be substituted at FuncsWithQuery().
// it is present here only for validation purposes, when there is no
// provided datasource.
//
// return non-empty slice to pass validation with chained functions in template
// see issue #989 for details
return []metric{{}}, nil
},
// first returns the first by order element from the given metrics list.
// usually used alongside with `query` template function.
"first": func(metrics []metric) (metric, error) {
if len(metrics) > 0 {
return metrics[0], nil
}
return metric{}, errors.New("first() called on vector with no elements")
},
// label returns the value of the given label name for the given metric.
// usually used alongside with `query` template function.
"label": func(label string, m metric) string {
return m.Labels[label]
},
// value returns the value of the given metric.
// usually used alongside with `query` template function.
"value": func(m metric) float64 {
return m.Value
},
// strvalue returns metric name.
"strvalue": func(m metric) string {
return m.Labels["__name__"]
},
// sortByLabel sorts the given metrics by provided label key
"sortByLabel": func(label string, metrics []metric) []metric {
sort.SliceStable(metrics, func(i, j int) bool {
return metrics[i].Labels[label] < metrics[j].Labels[label]
})
return metrics
},
/* Helpers */
// Converts a list of objects to a map with keys arg0, arg1 etc.
// This is intended to allow multiple arguments to be passed to templates.
"args": func(args ...interface{}) map[string]interface{} {
result := make(map[string]interface{})
for i, a := range args {
result[fmt.Sprintf("arg%d", i)] = a
}
return result
},
// safeHtml marks string as HTML not requiring auto-escaping.
//
// See also htmlEscape.
"safeHtml": func(text string) htmlTpl.HTML {
return htmlTpl.HTML(text)
},
}
}
// Time is the number of milliseconds since the epoch
// (1970-01-01 00:00 UTC) excluding leap seconds.
type Time int64
// timeFromUnixTimestamp returns the Time equivalent to t in unix timestamp.
func timeFromUnixTimestamp(t float64) Time {
return Time(t * 1e3)
}
// The number of nanoseconds per minimum tick.
const nanosPerTick = int64(minimumTick / time.Nanosecond)
// MinimumTick is the minimum supported time resolution. This has to be
// at least time.Second in order for the code below to work.
const minimumTick = time.Millisecond
// second is the Time duration equivalent to one second.
const second = int64(time.Second / minimumTick)
// Time returns the time.Time representation of t.
func (t Time) Time() time.Time {
return time.Unix(int64(t)/second, (int64(t)%second)*nanosPerTick)
}
func toFloat64(v interface{}) (float64, error) {
switch i := v.(type) {
case float64:
return i, nil
case float32:
return float64(i), nil
case int64:
return float64(i), nil
case int32:
return float64(i), nil
case int:
return float64(i), nil
case uint64:
return float64(i), nil
case uint32:
return float64(i), nil
case uint:
return float64(i), nil
case string:
return strconv.ParseFloat(i, 64)
default:
return 0, fmt.Errorf("unexpected value type %v", i)
}
}