88 lines
2.4 KiB
Go
88 lines
2.4 KiB
Go
package types
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import (
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"encoding"
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"errors"
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"fmt"
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"strings"
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"github.com/ryanuber/go-glob"
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)
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// Constraint holds a parsed constraint expression.
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// FIXME replace by a string.
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type Constraint struct {
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Key string `description:"The provider label that will be matched against. In practice, it is always 'tag'." export:"true"`
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// MustMatch is true if operator is "==" or false if operator is "!="
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MustMatch bool `description:"Whether the matching operator is equals or not equals." export:"true"`
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Value string `description:"The value that will be matched against." export:"true"` // TODO: support regex
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}
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// NewConstraint receives a string and return a *Constraint, after checking syntax and parsing the constraint expression.
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func NewConstraint(exp string) (*Constraint, error) {
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sep := ""
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constraint := &Constraint{}
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switch {
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case strings.Contains(exp, "=="):
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sep = "=="
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constraint.MustMatch = true
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case strings.Contains(exp, "!="):
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sep = "!="
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constraint.MustMatch = false
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default:
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return nil, errors.New("constraint expression missing valid operator: '==' or '!='")
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}
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kv := strings.SplitN(exp, sep, 2)
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if len(kv) == 2 {
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// At the moment, it only supports tags
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if kv[0] != "tag" {
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return nil, errors.New("constraint must be tag-based. Syntax: tag==us-*")
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}
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constraint.Key = kv[0]
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constraint.Value = kv[1]
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return constraint, nil
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}
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return nil, fmt.Errorf("incorrect constraint expression: %s", exp)
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}
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func (c *Constraint) String() string {
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if c.MustMatch {
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return c.Key + "==" + c.Value
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}
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return c.Key + "!=" + c.Value
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}
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var _ encoding.TextUnmarshaler = (*Constraint)(nil)
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// UnmarshalText defines how unmarshal in TOML parsing
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func (c *Constraint) UnmarshalText(text []byte) error {
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constraint, err := NewConstraint(string(text))
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if err != nil {
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return err
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}
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c.Key = constraint.Key
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c.MustMatch = constraint.MustMatch
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c.Value = constraint.Value
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return nil
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}
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var _ encoding.TextMarshaler = (*Constraint)(nil)
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// MarshalText encodes the receiver into UTF-8-encoded text and returns the result.
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func (c *Constraint) MarshalText() (text []byte, err error) {
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return []byte(c.String()), nil
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}
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// MatchConstraintWithAtLeastOneTag tests a constraint for one single service.
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func (c *Constraint) MatchConstraintWithAtLeastOneTag(tags []string) bool {
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for _, tag := range tags {
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if glob.Glob(c.Value, tag) {
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return true
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}
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}
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return false
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}
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