feat: support arbitrary prerelease strings

README.md

@@ -79,6 +79,15 @@ differences:
     on digest).
     </td>
   </tr>
+  <tr>
+    <td><code>tag_regex</code> <em>(Optional)</em></td>
+    <td>
+    Monitor semver tags that match the provided regular expression.
+    Results are sorted in semver order.
+    <br>
+    Takes precedence over <code>pre_releases</code>
+    </td>
+  </tr>
   <tr>
     <td><code>variant</code> <em>(Optional)</em></td>
     <td>
@@ -111,8 +120,14 @@ differences:
     Note however that variants and pre-releases both use the same syntax:
     `1.2.3-alpine` is technically also valid syntax for a Semver prerelease. For
     this reason, the resource will only consider prerelease data starting with
-    `alpha`, `beta`, or `rc` as a proper prerelease, treating anything else as
-    a variant.
+    `alpha`, `beta`, or `rc` as a proper prerelease, or values provided by
+    `pre_release_prefixes`, treating anything else as a variant.
+    </td>
+  </tr>
+  <tr>
+    <td><code>pre_release_prefixes</code> <em>(Optional)</em></td>
+    <td>
+    Opt in to additional pre-release prefixes (e.g. `build.3`)
     </td>
   </tr>
   <tr>

check_test.go

@@ -854,6 +854,30 @@ var _ = DescribeTable("tracking semver tags",
 			},
 		},
 	),
+	Entry("prerelease prefixes opted in",
+		SemverTagCheckExample{
+			Tags: map[string]string{
+				"1.0.0-alpha.1": "random-0",
+				"1.0.0":         "random-1",
+				"1.2.1-beta.1":  "random-2",
+				"1.2.1":         "random-3",
+				"2.0.0-rc.1":    "random-4",
+				"2.0.0":         "random-5",
+				"2.0.0-build.1": "random-6",
+			},
+			PreReleases: true,
+			PreReleasePrefixes: []string{"build"},
+			Versions: []string{
+				"1.0.0-alpha.1",
+				"1.0.0",
+				"1.2.1-beta.1",
+				"1.2.1",
+				"2.0.0-build.1",
+				"2.0.0-rc.1",
+				"2.0.0",
+			},
+		},
+	),
 	Entry("prereleases do not include 'variants'",
 		SemverTagCheckExample{
 			Tags: map[string]string{
@@ -1032,6 +1056,34 @@ var _ = DescribeTable("tracking semver tags",
 			},
 		},
 	),
+	Entry("opting in to prereleases allows additional '-' suffixes before variant",
+		SemverTagCheckExample{
+			Tags: map[string]string{
+				"1.0.0-build-foo":       "random-1",
+				"1.0.0-rc.1-foo":        "random-2",
+				"1.0.0-alpha.1-foo":     "random-3",
+				"1.0.0-beta.1-foo":      "random-4",
+				"1.0.0-bar-foo":         "random-5",
+				"1.0.0-rc.1-bar-foo":    "random-6",
+				"1.0.0-alpha.1-bar-foo": "random-7",
+				"1.0.0-beta.1-bar-foo":  "random-8",
+			},
+
+			Variant:     "foo",
+			PreReleases: true,
+			PreReleasePrefixes: []string{"build"},
+
+			Versions: []string{
+				"1.0.0-alpha.1-foo",
+				"1.0.0-alpha.1-bar-foo",
+				"1.0.0-beta.1-foo",
+				"1.0.0-beta.1-bar-foo",
+				"1.0.0-build-foo",
+				"1.0.0-rc.1-foo",
+				"1.0.0-rc.1-bar-foo",
+			},
+		},
+	),
 	Entry("tries mirror and falls back on original repository",
 		SemverTagCheckExample{
 			Tags: map[string]string{
@@ -1059,16 +1111,73 @@ var _ = DescribeTable("tracking semver tags",
 			Versions: []string{"1.0.0", "1.2.1", "2.0.0"},
 		},
 	),
+	Entry("tag regex for final versions",
+		SemverTagCheckExample{
+			Tags: map[string]string{
+				"1.0.0":         "random-1",
+				"1.0.0-alpha.1": "random-2",
+				"1.2.1":         "random-3",
+				"2.0.0":         "random-5",
+			},
+
+			TagRegex: "^[0-9].[0-9].[0-9]$",
+
+			Versions: []string{
+				"1.0.0",
+				"1.2.1",
+				"2.0.0",
+			},
+		},
+	),
+	Entry("tag regex for arbitrary prerelease",
+		SemverTagCheckExample{
+			Tags: map[string]string{
+				"1.0.0":         "random-1",
+				"1.0.0-alpha.1": "random-2",
+				"1.2.0-dev.1-built.123": "random-3",
+				"1.2.1":         "random-4",
+				"2.0.0":         "random-5",
+			},
+
+			TagRegex: "^[0-9]\\.[0-9]\\.[0-9]-dev\\.[0-9]+.built\\.[0-9]+$",
+
+			Versions: []string{
+				"1.2.0-dev.1-built.123",
+			},
+		},
+	),
+	Entry("combine tag regex, semver constraint, and variant",
+		SemverTagCheckExample{
+			Tags: map[string]string{
+				"1.1.0-dev.1-built.123-foo": "random-1",
+				"1.2.0-dev.1-built.123-foo": "random-2",
+				"1.3.0-dev.1-built.123-foo": "random-3",
+				"1.3.0-dev.1-built.123-bar": "random-4",
+			},
+
+			TagRegex: "^[0-9]\\.[0-9]\\.[0-9]-dev\\.[0-9]+.built\\.[0-9]+.*$",
+			Variant: "foo",
+			SemverConstraint: ">= 1.2.0-0",
+
+			Versions: []string{
+				"1.2.0-dev.1-built.123-foo",
+				"1.3.0-dev.1-built.123-foo",
+			},
+		},
+	),
 )
 
 type SemverTagCheckExample struct {
 	Tags map[string]string
 
 	PreReleases bool
+	PreReleasePrefixes []string
 	Variant     string
 
 	SemverConstraint string
 
+	TagRegex string
+
 	Repository     string
 	RegistryMirror string
 	WorkingMirror  bool
@@ -1101,10 +1210,12 @@ func (example SemverTagCheckExample) Run() {
 
 	req := resource.CheckRequest{
 		Source: resource.Source{
-			Repository:       repo.Name(),
-			PreReleases:      example.PreReleases,
-			Variant:          example.Variant,
-			SemverConstraint: example.SemverConstraint,
+			Repository:         repo.Name(),
+			PreReleases:        example.PreReleases,
+			PreReleasePrefixes: example.PreReleasePrefixes,
+			Variant:            example.Variant,
+			SemverConstraint:   example.SemverConstraint,
+			TagRegex:           example.TagRegex,
 		},
 	}
 

commands/check.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"sort"
 	"strings"
+	"regexp"
 
 	"github.com/Masterminds/semver/v3"
 	resource "github.com/concourse/registry-image-resource"
@@ -137,6 +138,14 @@ func checkRepository(repo name.Repository, source resource.Source, from *resourc
 		}
 	}
 
+	var regex *regexp.Regexp
+	if source.TagRegex != "" {
+		regex, err = regexp.Compile(source.TagRegex)
+		if err != nil {
+			return resource.CheckResponse{}, fmt.Errorf("parse tag regex: %w", err)
+		}
+	}
+
 	for _, identifier := range tags {
 		var ver *semver.Version
 		if identifier == bareTag {
@@ -162,23 +171,38 @@ func checkRepository(repo name.Repository, source resource.Source, from *resourc
 				continue
 			}
 
-			pre := ver.Prerelease()
-			if pre != "" {
-				// pre-releases not enabled; skip
-				if !source.PreReleases {
+			if regex != nil {
+				if ! regex.MatchString(identifier) {
 					continue
 				}
-
-				// contains additional variant
-				if strings.Contains(pre, "-") {
-					continue
-				}
-
-				if !strings.HasPrefix(pre, "alpha") &&
-					!strings.HasPrefix(pre, "beta") &&
-					!strings.HasPrefix(pre, "rc") {
-					// additional variant, not a prerelease segment
-					continue
+			} else {
+				pre := ver.Prerelease()
+				if pre != "" {
+					// pre-releases not enabled; skip
+					if !source.PreReleases {
+						continue
+					}
+
+					preReleasePrefixes := []string{"alpha", "beta", "rc"}
+					if source.PreReleasePrefixes != nil && len(source.PreReleasePrefixes) > 0 {
+						preReleasePrefixes = append(preReleasePrefixes, source.PreReleasePrefixes...)
+					} else {
+						if strings.Contains(pre, "-") {
+							// contains additional variant
+							continue
+						}
+					}
+
+					match := false
+					for _, prefix := range preReleasePrefixes {
+						if strings.HasPrefix(pre, prefix) {
+							match = true
+						}
+					}
+					if ! match {
+						// additional variant, not a prerelease segment
+						continue
+					}
 				}
 			}
 

types.go

@@ -88,12 +88,14 @@ type Source struct {
 
 	Insecure bool `json:"insecure"`
 
-	PreReleases bool   `json:"pre_releases,omitempty"`
-	Variant     string `json:"variant,omitempty"`
+	PreReleases bool `json:"pre_releases,omitempty"`
+	PreReleasePrefixes []string `json:"pre_release_prefixes,omitempty"`
+	Variant string `json:"variant,omitempty"`
 
 	SemverConstraint string `json:"semver_constraint,omitempty"`
 
 	Tag Tag `json:"tag,omitempty"`
+	TagRegex string `json:"tag_regex,omitempty"`
 
 	BasicCredentials
 	AwsCredentials