Image filtering with regular expressions

cluster/kubernetes/policies_test.go

@@ -149,6 +149,23 @@ func TestUpdatePolicies(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "add regexp tag policy",
+			in:   nil,
+			out:  []string{"flux.weave.works/tag.nginx", "regexp:(.*?)"},
+			update: policy.Update{
+				Add: policy.Set{policy.TagPrefix("nginx"): "regexp:(.*?)"},
+			},
+		},
+		{
+			name: "add invalid regexp tag policy",
+			in:   nil,
+			out:  []string{"flux.weave.works/tag.nginx", "regexp:(.*?)"},
+			update: policy.Update{
+				Add: policy.Set{policy.TagPrefix("nginx"): "regexp:*"},
+			},
+			wantErr: true,
+		},
 	} {
 		t.Run(c.name, func(t *testing.T) {
 			caseIn := templToString(t, annotationsTemplate, c.in)

policy/pattern.go

@@ -5,11 +5,13 @@ import (
 	"github.com/ryanuber/go-glob"
 	"github.com/weaveworks/flux/image"
 	"strings"
+	"regexp"
 )
 
 const (
 	globPrefix   = "glob:"
 	semverPrefix = "semver:"
+	regexpPrefix = "regexp:"
 )
 
 var (
@@ -39,17 +41,28 @@ type SemverPattern struct {
 	constraints *semver.Constraints
 }
 
-// NewPattern instantiates a Pattern according to the prefix
-// it finds. The prefix can be either `glob:` (default if omitted)
-// or `semver:`.
+// RegexpPattern matches by regular expression.
+type RegexpPattern struct {
+	pattern	string // pattern without prefix
+	regexp	*regexp.Regexp
+}
 
+// NewPattern instantiates a Pattern according to the prefix
+// it finds. The prefix can be either `glob:` (default if omitted),
+// `semver:` or `regexp:`.
 func NewPattern(pattern string) Pattern {
-	if strings.HasPrefix(pattern, semverPrefix) {
+	switch {
+	case strings.HasPrefix(pattern, semverPrefix):
 		pattern = strings.TrimPrefix(pattern, semverPrefix)
 		c, _ := semver.NewConstraint(pattern)
 		return SemverPattern{pattern, c}
+	case strings.HasPrefix(pattern, regexpPrefix):
+		pattern = strings.TrimPrefix(pattern, regexpPrefix)
+		r, _ := regexp.Compile(pattern)
+		return RegexpPattern{pattern, r}
+	default:
+		return GlobPattern(strings.TrimPrefix(pattern, globPrefix))
 	}
-	return GlobPattern(strings.TrimPrefix(pattern, globPrefix))
 }
 
 func (g GlobPattern) Matches(tag string) bool {
@@ -91,3 +104,23 @@ func (s SemverPattern) Newer(a, b *image.Info) bool {
 func (s SemverPattern) Valid() bool {
 	return s.constraints != nil
 }
+
+func (r RegexpPattern) Matches(tag string) bool {
+	if r.regexp == nil {
+		// Invalid regexp match anything
+		return true
+	}
+	return r.regexp.MatchString(tag)
+}
+
+func (r RegexpPattern) String() string {
+	return regexpPrefix + r.pattern
+}
+
+func (r RegexpPattern) Newer(a, b *image.Info) bool {
+	return image.NewerByCreated(a, b)
+}
+
+func (r RegexpPattern) Valid() bool {
+	return r.regexp != nil
+}

policy/pattern_test.go

@@ -86,3 +86,38 @@ func TestSemverPattern_Matches(t *testing.T) {
 		}
 	}
 }
+
+func TestRegexpPattern_Matches(t *testing.T) {
+	for _, tt := range []struct {
+		name    string
+		pattern string
+		true    []string
+		false   []string
+	}{
+		{
+			name:    "all prefixed",
+			pattern: "regexp:(.*?)",
+			true:    []string{"", "1", "foo"},
+			false:   nil,
+		},
+		{
+			name:    "regexp",
+			pattern: "regexp:^([a-zA-Z]+)$",
+			true:    []string{"foo", "BAR", "fooBAR"},
+			false:   []string{"1", "foo-1"},
+		},
+	} {
+		pattern := NewPattern(tt.pattern)
+		assert.IsType(t, RegexpPattern{}, pattern)
+		for _, tag := range tt.true {
+			t.Run(fmt.Sprintf("%s[%q]", tt.name, tag), func(t *testing.T) {
+				assert.True(t, pattern.Matches(tag))
+			})
+		}
+		for _, tag := range tt.false {
+			t.Run(fmt.Sprintf("%s[%q]", tt.name, tag), func(t *testing.T) {
+				assert.False(t, pattern.Matches(tag))
+			})
+		}
+	}
+}

site/using.md

@@ -430,6 +430,11 @@ fluxctl policy --controller=default:deployment/helloworld --tag-all='semver:*'
 Using a semver filter will also affect how flux sorts images, so
 that the higher versions will be considered newer.
 
+If your images have complex tags you can filter by regular expression:
+```
+fluxctl policy --controller=default:deployment/helloworld --tag-all='regexp:^([a-zA-Z]+)$'
+```
+
 ## Actions triggered through `fluxctl`
 
 `fluxctl` provides the following flags for the message and author customization: