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vmalert: do not execute templates during validation (#2528)

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Function `ValidateTemplates`, used on the vmalert startup,
is supposed to check whether used templates and functions
in loaded rules are correct. The function was parsing
and executing loaded templates.
However, rules may contain functions which can't be executed
without values (label values or query results), like `slice`.
Because of this, validation for completely valid expression
`{{ slice $labels.job 9 }}` will fail since `$labels.job`
is empty during validation.

This PR updates `ValidateTemplates` function to only parse
templates without executing them.

https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2514
Signed-off-by: hagen1778 <roman@victoriametrics.com>
This commit is contained in:
Roman Khavronenko 2022-05-02 10:16:16 +02:00 committed by GitHub
parent 32a6b67e6c
commit 3616337812
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 9 additions and 6 deletions
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15
app/vmalert/notifier/alert.go
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@ -92,12 +92,12 @@ var tplHeaders = []string{
// requires a queryFunction as an argument.
func (a *Alert) ExecTemplate(q QueryFn, labels, annotations map[string]string) (map[string]string, error) {
tplData := AlertTplData{Value: a.Value, Labels: labels, Expr: a.Expr}
return templateAnnotations(annotations, tplData, funcsWithQuery(q))
return templateAnnotations(annotations, tplData, funcsWithQuery(q), true)
}
// ExecTemplate executes the given template for given annotations map.
func ExecTemplate(q QueryFn, annotations map[string]string, tpl AlertTplData) (map[string]string, error) {
return templateAnnotations(annotations, tpl, funcsWithQuery(q))
return templateAnnotations(annotations, tpl, funcsWithQuery(q), true)
}
// ValidateTemplates validate annotations for possible template error, uses empty data for template population
@ -105,11 +105,11 @@ func ValidateTemplates(annotations map[string]string) error {
_, err := templateAnnotations(annotations, AlertTplData{
Labels: map[string]string{},
Value: 0,
}, tmplFunc)
}, tmplFunc, false)
return err
}
func templateAnnotations(annotations map[string]string, data AlertTplData, funcs template.FuncMap) (map[string]string, error) {
func templateAnnotations(annotations map[string]string, data AlertTplData, funcs template.FuncMap, execute bool) (map[string]string, error) {
var builder strings.Builder
var buf bytes.Buffer
eg := new(utils.ErrGroup)
@ -122,7 +122,7 @@ func templateAnnotations(annotations map[string]string, data AlertTplData, funcs
builder.Grow(len(header) + len(text))
builder.WriteString(header)
builder.WriteString(text)
if err := templateAnnotation(&buf, builder.String(), tData, funcs); err != nil {
if err := templateAnnotation(&buf, builder.String(), tData, funcs, execute); err != nil {
r[key] = text
eg.Add(fmt.Errorf("key %q, template %q: %w", key, text, err))
continue
@ -138,12 +138,15 @@ type tplData struct {
ExternalURL string
}
func templateAnnotation(dst io.Writer, text string, data tplData, funcs template.FuncMap) error {
func templateAnnotation(dst io.Writer, text string, data tplData, funcs template.FuncMap, execute bool) error {
t := template.New("").Funcs(funcs).Option("missingkey=zero")
tpl, err := t.Parse(text)
if err != nil {
return fmt.Errorf("error parsing annotation: %w", err)
}
if !execute {
return nil
}
if err = tpl.Execute(dst, data); err != nil {
return fmt.Errorf("error evaluating annotation template: %w", err)
}