Merge pull request #736 from stevvooe/repository-name-clarification

Clarify repository naming constraints for registry API

common/names.go

@@ -1,13 +1,25 @@
 package common
 
 import (
+	"fmt"
 	"regexp"
+	"strings"
+)
+
+const (
+	RepositoryNameComponentMinLength = 2
+	RepositoryNameComponentMaxLength = 30
+
+	RepositoryNameMinComponents  = 2
+	RepositoryNameMaxComponents  = 5
+	RepositoryNameTotalLengthMax = 255
 )
 
 // RepositoryNameComponentRegexp restricts registtry path components names to
 // start with at least two letters or numbers, with following parts able to
 // separated by one period, dash or underscore.
-var RepositoryNameComponentRegexp = regexp.MustCompile(`[a-z0-9]{2,}(?:[._-][a-z0-9]+)*`)
+var RepositoryNameComponentRegexp = regexp.MustCompile(`[a-z0-9]+(?:[._-][a-z0-9]+)*`)
+var RepositoryNameComponentAnchoredRegexp = regexp.MustCompile(`^` + RepositoryNameComponentRegexp.String() + `$`)
 
 // TODO(stevvooe): RepositoryName needs to be limited to some fixed length.
 // Looking path prefixes and s3 limitation of 1024, this should likely be
@@ -21,3 +33,50 @@ var RepositoryNameRegexp = regexp.MustCompile(`(?:` + RepositoryNameComponentReg
 var TagNameRegexp = regexp.MustCompile(`[\w][\w.-]{0,127}`)
 
 // TODO(stevvooe): Contribute these exports back to core, so they are shared.
+
+var (
+	ErrRepositoryNameComponentShort = fmt.Errorf("respository name component must be %v or more characters", RepositoryNameComponentMinLength)
+	ErrRepositoryNameComponentLong  = fmt.Errorf("respository name component must be %v characters or less", RepositoryNameComponentMaxLength)
+
+	ErrRepositoryNameMissingComponents = fmt.Errorf("repository name must have at least %v components", RepositoryNameMinComponents)
+	ErrRepositoryNameTooManyComponents = fmt.Errorf("repository name %v or less components", RepositoryNameMaxComponents)
+
+	ErrRepositoryNameLong             = fmt.Errorf("repository name must not be more than %v characters", RepositoryNameTotalLengthMax)
+	ErrRepositoryNameComponentInvalid = fmt.Errorf("repository name component must match %q", RepositoryNameComponentRegexp.String())
+)
+
+// ValidateRespositoryName ensures the repository name is valid for use in the
+// registry. This function accepts a superset of what might be accepted by
+// docker core or docker hub. If the name does not pass validation, an error,
+// describing the conditions, is returned.
+func ValidateRespositoryName(name string) error {
+	if len(name) > RepositoryNameTotalLengthMax {
+		return ErrRepositoryNameLong
+	}
+
+	components := strings.Split(name, "/")
+
+	if len(components) < RepositoryNameMinComponents {
+		return ErrRepositoryNameMissingComponents
+	}
+
+	if len(components) > RepositoryNameMaxComponents {
+		return ErrRepositoryNameTooManyComponents
+	}
+
+	for _, component := range components {
+		if len(component) < RepositoryNameComponentMinLength {
+			return ErrRepositoryNameComponentShort
+		}
+
+		if len(component) > RepositoryNameComponentMaxLength {
+			return ErrRepositoryNameComponentLong
+		}
+
+		if !RepositoryNameComponentAnchoredRegexp.MatchString(component) {
+			return ErrRepositoryNameComponentInvalid
+		}
+	}
+
+	return nil
+}

common/names_test.go

@@ -7,56 +7,85 @@ import (
 func TestRepositoryNameRegexp(t *testing.T) {
 	for _, testcase := range []struct {
 		input string
-		valid bool
+		err   error
 	}{
 		{
 			input: "simple/name",
-			valid: true,
 		},
 		{
 			input: "library/ubuntu",
-			valid: true,
 		},
 		{
 			input: "docker/stevvooe/app",
-			valid: true,
 		},
 		{
 			input: "aa/aa/aa/aa/aa/aa/aa/aa/aa/bb/bb/bb/bb/bb/bb",
-			valid: true,
+			err:   ErrRepositoryNameTooManyComponents,
 		},
 		{
-			input: "a/a/a/a/a/a/b/b/b/b",
-			valid: false,
+			input: "aa/aa/bb/bb/bb",
+		},
+		{
+			input: "a/a/a/b/b",
+			err:   ErrRepositoryNameComponentShort,
 		},
 		{
 			input: "a/a/a/a/",
-			valid: false,
+			err:   ErrRepositoryNameComponentShort,
 		},
 		{
 			input: "foo.com/bar/baz",
-			valid: true,
 		},
 		{
 			input: "blog.foo.com/bar/baz",
-			valid: true,
 		},
 		{
 			input: "asdf",
-			valid: false,
+			err:   ErrRepositoryNameMissingComponents,
 		},
 		{
-			input: "asdf$$^/",
-			valid: false,
+			input: "asdf$$^/aa",
+			err:   ErrRepositoryNameComponentInvalid,
+		},
+		{
+			input: "aa-a/aa",
+		},
+		{
+			input: "aa/aa",
+		},
+		{
+			input: "a-a/a-a",
+		},
+		{
+			input: "a",
+			err:   ErrRepositoryNameMissingComponents,
+		},
+		{
+			input: "a-/a/a/a",
+			err:   ErrRepositoryNameComponentInvalid,
 		},
 	} {
-		if RepositoryNameRegexp.MatchString(testcase.input) != testcase.valid {
-			status := "invalid"
-			if testcase.valid {
-				status = "valid"
-			}
 
-			t.Fatalf("expected %q to be %s repository name", testcase.input, status)
+		failf := func(format string, v ...interface{}) {
+			t.Logf(testcase.input+": "+format, v...)
+			t.Fail()
+		}
+
+		if err := ValidateRespositoryName(testcase.input); err != testcase.err {
+			if testcase.err != nil {
+				if err != nil {
+					failf("unexpected error for invalid repository: got %v, expected %v", err, testcase.err)
+				} else {
+					failf("expected invalid repository: %v", testcase.err)
+				}
+			} else {
+				if err != nil {
+					// Wrong error returned.
+					failf("unexpected error validating repository name: %v, expected %v", err, testcase.err)
+				} else {
+					failf("unexpected error validating repository name: %v", err)
+				}
+			}
 		}
 	}
 }