mirror of https://github.com/grafana/grafana
Alexander Akhmetov
4 months ago
parent
0961de396e
commit
641e53753e
@ -0,0 +1,132 @@ |
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package prom |
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import ( |
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"reflect" |
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"strings" |
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"text/template/parse" |
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) |
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const ( |
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PrometheusModeTemplateCall = "{{- _prometheusMode -}}" |
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) |
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func convertTemplates(m map[string]string) error { |
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for k, v := range m { |
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nv, err := convertTemplate(v) |
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if err != nil { |
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return err |
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} |
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m[k] = nv |
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} |
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return nil |
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} |
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// convertTemplate analyzes a template string to determine if it uses Prometheus-style
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// value references ($value or .Value). If it does, it adds a _prometheusMode function call
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// to the beginning of the template to switch the template rendering to Prometheus compatibility mode.
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// This allows templates converted from Prometheus alerting rules to continue working without modification.
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func convertTemplate(tmpl string) (string, error) { |
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searchFor := map[string]struct{}{ |
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"$value": {}, |
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".Value": {}, |
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"$.Value": {}, |
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} |
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// Create a parser with SkipFuncCheck to avoid errors with unknown functions
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p := parse.New("tmpl") |
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p.Mode = parse.ParseComments | parse.SkipFuncCheck |
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// Add temporary prefix with the variables that are expected by the template,
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// otherwise the parsing fails.
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tmpPrefix := `{{$value := ""}}{{$labels := ""}}` |
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tree, err := p.Parse(tmpPrefix+tmpl, "{{", "}}", map[string]*parse.Tree{}) |
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if err != nil { |
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return "", err |
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} |
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// Search for the variables in the template
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found := walkNodes(tree.Root, searchFor) |
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if found { |
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return PrometheusModeTemplateCall + tmpl, nil |
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} |
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return tmpl, nil |
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} |
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// walkNodes recursively traverses the AST to find all variable nodes with certain names
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// and returns the boolean indicating whether they are present in the template.
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func walkNodes(node parse.Node, searchFor map[string]struct{}) bool { |
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var found bool |
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var walk func(node parse.Node) |
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walk = func(node parse.Node) { |
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if node == nil || reflect.ValueOf(node).IsNil() { |
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return |
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} |
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switch n := node.(type) { |
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case *parse.VariableNode: |
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if _, ok := searchFor[strings.Join(n.Ident, ".")]; ok { |
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found = true |
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} |
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case *parse.FieldNode: |
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if _, ok := searchFor["."+strings.Join(n.Ident, ".")]; ok { |
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found = true |
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} |
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case *parse.ActionNode: |
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walk(n.Pipe) |
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case *parse.ChainNode: |
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walk(n.Node) |
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case *parse.CommandNode: |
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for _, arg := range n.Args { |
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walk(arg) |
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} |
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case *parse.ListNode: |
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for _, child := range n.Nodes { |
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walk(child) |
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} |
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case *parse.PipeNode: |
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for _, cmd := range n.Cmds { |
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walk(cmd) |
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} |
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case *parse.IfNode: |
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walk(n.Pipe) |
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walk(n.List) |
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if n.ElseList != nil { |
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walk(n.ElseList) |
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} |
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case *parse.RangeNode: |
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walk(n.Pipe) |
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walk(n.List) |
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if n.ElseList != nil { |
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walk(n.ElseList) |
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} |
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case *parse.WithNode: |
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walk(n.Pipe) |
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walk(n.List) |
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if n.ElseList != nil { |
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walk(n.ElseList) |
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} |
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case *parse.TemplateNode: |
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if n.Pipe != nil { |
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walk(n.Pipe) |
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} |
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} |
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} |
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walk(node) |
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return found |
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} |
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@ -0,0 +1,180 @@ |
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package prom |
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import ( |
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"testing" |
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"github.com/stretchr/testify/require" |
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) |
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func TestConvertTemplates(t *testing.T) { |
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testCases := []struct { |
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name string |
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templates map[string]string |
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expected map[string]string |
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shouldFail bool |
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}{ |
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{ |
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name: "simple template with $value", |
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templates: map[string]string{ |
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"template": "Value is {{$value}}", |
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}, |
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expected: map[string]string{ |
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"template": "{{- _prometheusMode -}}Value is {{$value}}", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "simple template with .Value", |
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templates: map[string]string{ |
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"template": "Value is {{.Value}}", |
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}, |
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expected: map[string]string{ |
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"template": "{{- _prometheusMode -}}Value is {{.Value}}", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "template with $.Value", |
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templates: map[string]string{ |
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"template": ` |
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{{- range .Items}} |
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Value: {{.Value}} |
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Global Value: {{$.Value}} |
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{{- end}} |
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`, |
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}, |
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expected: map[string]string{ |
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"template": `{{- _prometheusMode -}} |
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{{- range .Items}} |
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Value: {{.Value}} |
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Global Value: {{$.Value}} |
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{{- end}} |
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`, |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "complex template with $value in if statement", |
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templates: map[string]string{ |
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"template": "{{if gt $value 100.0}}Too high{{else}}Good{{end}}", |
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}, |
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expected: map[string]string{ |
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"template": "{{- _prometheusMode -}}{{if gt $value 100.0}}Too high{{else}}Good{{end}}", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "complex template with .Value in if statement", |
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templates: map[string]string{ |
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"template": "{{if gt .Value 100.0}}Too high{{else}}Good{{end}}", |
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}, |
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expected: map[string]string{ |
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"template": "{{- _prometheusMode -}}{{if gt .Value 100.0}}Too high{{else}}Good{{end}}", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "template with $value in nested structures", |
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templates: map[string]string{ |
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"template": "{{range .Values}}{{if eq . $value}}Match{{end}}{{end}}", |
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}, |
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expected: map[string]string{ |
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"template": "{{- _prometheusMode -}}{{range .Values}}{{if eq . $value}}Match{{end}}{{end}}", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "template without $value or .Value", |
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templates: map[string]string{ |
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"template": "This template does not use the values", |
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}, |
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expected: map[string]string{ |
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"template": "This template does not use the values", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "template with $labels", |
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templates: map[string]string{ |
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"template": "Instance: {{ $labels.instance }}", |
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}, |
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expected: map[string]string{ |
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"template": "Instance: {{ $labels.instance }}", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "template with both $value and $labels", |
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templates: map[string]string{ |
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"template": "{{ $labels.instance }} has value {{ $value }}", |
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}, |
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expected: map[string]string{ |
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"template": "{{- _prometheusMode -}}{{ $labels.instance }} has value {{ $value }}", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "template with multiple $value occurrences", |
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templates: map[string]string{ |
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"template": "First: {{ $value }}, Second: {{ $value }}", |
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}, |
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expected: map[string]string{ |
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"template": "{{- _prometheusMode -}}First: {{ $value }}, Second: {{ $value }}", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "multiple templates with mixed patterns", |
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templates: map[string]string{ |
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"summary": "Instance {{ $labels.instance }} has high CPU usage", |
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"description": "{{ $labels.instance }} has value {{ $value }}", |
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}, |
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expected: map[string]string{ |
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"summary": "Instance {{ $labels.instance }} has high CPU usage", |
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"description": "{{- _prometheusMode -}}{{ $labels.instance }} has value {{ $value }}", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "all templates with values", |
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templates: map[string]string{ |
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"summary": "Value is {{ $value }}", |
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"description": "Detailed value is {{ .Value }}", |
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}, |
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expected: map[string]string{ |
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"summary": "{{- _prometheusMode -}}Value is {{ $value }}", |
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"description": "{{- _prometheusMode -}}Detailed value is {{ .Value }}", |
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}, |
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shouldFail: false, |
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}, |
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{ |
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name: "no templates with values", |
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templates: map[string]string{ |
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"summary": "Instance {{ $labels.instance }} is down", |
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"description": "Instance {{ $labels.instance }} has been down for more than 5 minutes", |
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}, |
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expected: map[string]string{ |
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"summary": "Instance {{ $labels.instance }} is down", |
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"description": "Instance {{ $labels.instance }} has been down for more than 5 minutes", |
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}, |
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shouldFail: false, |
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}, |
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} |
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for _, tc := range testCases { |
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t.Run(tc.name, func(t *testing.T) { |
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input := make(map[string]string) |
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for k, v := range tc.templates { |
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input[k] = v |
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} |
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err := convertTemplates(input) |
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if tc.shouldFail { |
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require.Error(t, err) |
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} else { |
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require.NoError(t, err) |
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require.Equal(t, tc.expected, input) |
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} |
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}) |
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} |
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} |
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