100 lines
2.3 KiB
Go
100 lines
2.3 KiB
Go
package constraints
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import (
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"errors"
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"regexp"
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"strings"
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"github.com/vulcand/predicate"
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)
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// MarathonConstraintPrefix is the prefix for each label's key created from a Marathon application constraint.
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// It is used in order to create a specific and unique pattern for these labels.
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const MarathonConstraintPrefix = "Traefik-Marathon-505F9E15-BDC7-45E7-828D-C06C7BAB8091"
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type constraintFunc func(map[string]string) bool
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// Match reports whether the expression matches with the given labels.
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// The expression must match any logical boolean combination of:
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// - `Label(labelName, labelValue)`
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// - `LabelRegex(labelName, regexValue)`
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// - `MarathonConstraint(field:operator:value)`
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func Match(labels map[string]string, expr string) (bool, error) {
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if expr == "" {
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return true, nil
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}
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p, err := predicate.NewParser(predicate.Def{
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Operators: predicate.Operators{
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AND: andFunc,
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NOT: notFunc,
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OR: orFunc,
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},
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Functions: map[string]interface{}{
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"Label": labelFn,
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"LabelRegex": labelRegexFn,
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"MarathonConstraint": marathonFn,
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},
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})
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if err != nil {
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return false, err
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}
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parse, err := p.Parse(expr)
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if err != nil {
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return false, err
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}
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fn, ok := parse.(constraintFunc)
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if !ok {
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return false, errors.New("not a constraintFunc")
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}
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return fn(labels), nil
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}
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func labelFn(name, value string) constraintFunc {
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return func(labels map[string]string) bool {
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return labels[name] == value
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}
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}
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func labelRegexFn(name, expr string) constraintFunc {
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return func(labels map[string]string) bool {
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matched, err := regexp.MatchString(expr, labels[name])
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if err != nil {
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return false
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}
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return matched
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}
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}
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func marathonFn(value string) constraintFunc {
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return func(labels map[string]string) bool {
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for k, v := range labels {
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if strings.HasPrefix(k, MarathonConstraintPrefix) {
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if v == value {
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return true
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}
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}
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}
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return false
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}
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}
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func andFunc(a, b constraintFunc) constraintFunc {
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return func(labels map[string]string) bool {
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return a(labels) && b(labels)
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}
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}
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func orFunc(a, b constraintFunc) constraintFunc {
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return func(labels map[string]string) bool {
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return a(labels) || b(labels)
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}
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}
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func notFunc(a constraintFunc) constraintFunc {
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return func(labels map[string]string) bool {
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return !a(labels)
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}
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}
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