traefik/types/constraints.go

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2018-11-14 09:18:03 +00:00
package types
import (
"encoding"
"errors"
"fmt"
"strings"
"github.com/ryanuber/go-glob"
)
// Constraint holds a parsed constraint expression.
type Constraint struct {
Key string `export:"true"`
// MustMatch is true if operator is "==" or false if operator is "!="
MustMatch bool `export:"true"`
// TODO: support regex
Regex string `export:"true"`
}
// NewConstraint receives a string and return a *Constraint, after checking syntax and parsing the constraint expression.
func NewConstraint(exp string) (*Constraint, error) {
sep := ""
constraint := &Constraint{}
if strings.Contains(exp, "==") {
sep = "=="
constraint.MustMatch = true
} else if strings.Contains(exp, "!=") {
sep = "!="
constraint.MustMatch = false
} else {
return nil, errors.New("constraint expression missing valid operator: '==' or '!='")
}
kv := strings.SplitN(exp, sep, 2)
if len(kv) == 2 {
// At the moment, it only supports tags
if kv[0] != "tag" {
return nil, errors.New("constraint must be tag-based. Syntax: tag==us-*")
}
constraint.Key = kv[0]
constraint.Regex = kv[1]
return constraint, nil
}
return nil, fmt.Errorf("incorrect constraint expression: %s", exp)
}
func (c *Constraint) String() string {
if c.MustMatch {
return c.Key + "==" + c.Regex
}
return c.Key + "!=" + c.Regex
}
var _ encoding.TextUnmarshaler = (*Constraint)(nil)
// UnmarshalText defines how unmarshal in TOML parsing
func (c *Constraint) UnmarshalText(text []byte) error {
constraint, err := NewConstraint(string(text))
if err != nil {
return err
}
c.Key = constraint.Key
c.MustMatch = constraint.MustMatch
c.Regex = constraint.Regex
return nil
}
var _ encoding.TextMarshaler = (*Constraint)(nil)
// MarshalText encodes the receiver into UTF-8-encoded text and returns the result.
func (c *Constraint) MarshalText() (text []byte, err error) {
return []byte(c.String()), nil
}
// MatchConstraintWithAtLeastOneTag tests a constraint for one single service.
func (c *Constraint) MatchConstraintWithAtLeastOneTag(tags []string) bool {
for _, tag := range tags {
if glob.Glob(c.Regex, tag) {
return true
}
}
return false
}
// Set []*Constraint.
func (cs *Constraints) Set(str string) error {
exps := strings.Split(str, ",")
if len(exps) == 0 {
return fmt.Errorf("bad Constraint format: %s", str)
}
for _, exp := range exps {
constraint, err := NewConstraint(exp)
if err != nil {
return err
}
*cs = append(*cs, constraint)
}
return nil
}
// Constraints holds a Constraint parser.
type Constraints []*Constraint
// Get []*Constraint
func (cs *Constraints) Get() interface{} { return []*Constraint(*cs) }
// String returns []*Constraint in string.
func (cs *Constraints) String() string { return fmt.Sprintf("%+v", *cs) }
// SetValue sets []*Constraint into the parser.
func (cs *Constraints) SetValue(val interface{}) {
*cs = val.(Constraints)
}
// Type exports the Constraints type as a string.
func (cs *Constraints) Type() string {
return "constraint"
}