open-nomad/helper/constraints/semver/constraints.go
Michael Schurter 796758b8a5 core: add semver constraint
The existing version constraint uses logic optimized for package
managers, not schedulers, when checking prereleases:

- 1.3.0-beta1 will *not* satisfy ">= 0.6.1"
- 1.7.0-rc1 will *not* satisfy ">= 1.6.0-beta1"

This is due to package managers wishing to favor final releases over
prereleases.

In a scheduler versions more often represent the earliest release all
required features/APIs are available in a system. Whether the constraint
or the version being evaluated are prereleases has no impact on
ordering.

This commit adds a new constraint - `semver` - which will use Semver
v2.0 ordering when evaluating constraints. Given the above examples:

- 1.3.0-beta1 satisfies ">= 0.6.1" using `semver`
- 1.7.0-rc1 satisfies ">= 1.6.0-beta1" using `semver`

Since existing jobspecs may rely on the old behavior, a new constraint
was added and the implicit Consul Connect and Vault constraints were
updated to use it.
2019-11-19 08:40:19 -08:00

148 lines
3.4 KiB
Go

// semver is a Semver Constraints package copied from
// github.com/hashicorp/go-version @ 2046c9d0f0b03c779670f5186a2a4b2c85493a71
//
// Unlike Constraints in go-version, Semver constraints use Semver 2.0 ordering
// rules and only accept properly formatted Semver versions.
package semver
import (
"fmt"
"regexp"
"strings"
"github.com/hashicorp/go-version"
)
// Constraint represents a single constraint for a version, such as ">=
// 1.0".
type Constraint struct {
f constraintFunc
check *version.Version
original string
}
// Constraints is a slice of constraints. We make a custom type so that
// we can add methods to it.
type Constraints []*Constraint
type constraintFunc func(v, c *version.Version) bool
var constraintOperators map[string]constraintFunc
var constraintRegexp *regexp.Regexp
func init() {
constraintOperators = map[string]constraintFunc{
"": constraintEqual,
"=": constraintEqual,
"!=": constraintNotEqual,
">": constraintGreaterThan,
"<": constraintLessThan,
">=": constraintGreaterThanEqual,
"<=": constraintLessThanEqual,
}
ops := make([]string, 0, len(constraintOperators))
for k := range constraintOperators {
ops = append(ops, regexp.QuoteMeta(k))
}
constraintRegexp = regexp.MustCompile(fmt.Sprintf(
`^\s*(%s)\s*(%s)\s*$`,
strings.Join(ops, "|"),
version.SemverRegexpRaw))
}
// NewConstraint will parse one or more constraints from the given
// constraint string. The string must be a comma-separated list of constraints.
func NewConstraint(v string) (Constraints, error) {
vs := strings.Split(v, ",")
result := make([]*Constraint, len(vs))
for i, single := range vs {
c, err := parseSingle(single)
if err != nil {
return nil, err
}
result[i] = c
}
return Constraints(result), nil
}
// Check tests if a version satisfies all the constraints.
func (cs Constraints) Check(v *version.Version) bool {
for _, c := range cs {
if !c.Check(v) {
return false
}
}
return true
}
// Returns the string format of the constraints
func (cs Constraints) String() string {
csStr := make([]string, len(cs))
for i, c := range cs {
csStr[i] = c.String()
}
return strings.Join(csStr, ",")
}
// Check tests if a constraint is validated by the given version.
func (c *Constraint) Check(v *version.Version) bool {
return c.f(v, c.check)
}
func (c *Constraint) String() string {
return c.original
}
func parseSingle(v string) (*Constraint, error) {
matches := constraintRegexp.FindStringSubmatch(v)
if matches == nil {
return nil, fmt.Errorf("Malformed constraint: %s", v)
}
check, err := version.NewSemver(matches[2])
if err != nil {
return nil, err
}
return &Constraint{
f: constraintOperators[matches[1]],
check: check,
original: v,
}, nil
}
//-------------------------------------------------------------------
// Constraint functions
//-------------------------------------------------------------------
func constraintEqual(v, c *version.Version) bool {
return v.Equal(c)
}
func constraintNotEqual(v, c *version.Version) bool {
return !v.Equal(c)
}
func constraintGreaterThan(v, c *version.Version) bool {
return v.Compare(c) == 1
}
func constraintLessThan(v, c *version.Version) bool {
return v.Compare(c) == -1
}
func constraintGreaterThanEqual(v, c *version.Version) bool {
return v.Compare(c) >= 0
}
func constraintLessThanEqual(v, c *version.Version) bool {
return v.Compare(c) <= 0
}