cli-plugins/manager: allow schema-versions <= 2.0.0

cli-plugins/manager/candidate_test.go

@@ -55,6 +55,7 @@ func TestValidateCandidate(t *testing.T) {
 		// Either err or invalid may be non-empty, but not both (both can be empty for a good plugin).
 		err     string
 		invalid string
+		expVer  string
 	}{
 		// Invalid cases.
 		{
@@ -95,12 +96,17 @@ func TestValidateCandidate(t *testing.T) {
 		{
 			name:    "empty schemaversion",
 			plugin:  &fakeCandidate{path: goodPluginPath, exec: true, meta: `{}`},
-			invalid: `plugin SchemaVersion "" is not valid`,
+			invalid: `plugin SchemaVersion version cannot be empty`,
 		},
 		{
 			name:    "invalid schemaversion",
 			plugin:  &fakeCandidate{path: goodPluginPath, exec: true, meta: `{"SchemaVersion": "xyzzy"}`},
-			invalid: `plugin SchemaVersion "xyzzy" is not valid`,
+			invalid: `plugin SchemaVersion "xyzzy" has wrong format: must be <major>.<minor>.<patch>`,
+		},
+		{
+			name:    "invalid schemaversion major",
+			plugin:  &fakeCandidate{path: goodPluginPath, exec: true, meta: `{"SchemaVersion": "2.0.0"}`},
+			invalid: `plugin SchemaVersion "2.0.0" is not supported: must be lower than 2.0.0`,
 		},
 		{
 			name:    "no vendor",
@@ -117,11 +123,25 @@ func TestValidateCandidate(t *testing.T) {
 		{
 			name:   "valid",
 			plugin: &fakeCandidate{path: goodPluginPath, exec: true, meta: `{"SchemaVersion": "0.1.0", "Vendor": "e2e-testing"}`},
+			expVer: "0.1.0",
 		},
 		{
 			// Including the deprecated "experimental" field should not break processing.
 			name:   "with legacy experimental",
 			plugin: &fakeCandidate{path: goodPluginPath, exec: true, meta: `{"SchemaVersion": "0.1.0", "Vendor": "e2e-testing", "Experimental": true}`},
+			expVer: "0.1.0",
+		},
+		{
+			// note that this may not be supported by older CLIs
+			name:   "new minor schema version",
+			plugin: &fakeCandidate{path: goodPluginPath, exec: true, meta: `{"SchemaVersion": "0.2.0", "Vendor": "e2e-testing"}`},
+			expVer: "0.2.0",
+		},
+		{
+			// note that this may not be supported by older CLIs
+			name:   "new major schema version",
+			plugin: &fakeCandidate{path: goodPluginPath, exec: true, meta: `{"SchemaVersion": "1.0.0", "Vendor": "e2e-testing"}`},
+			expVer: "1.0.0",
 		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
@@ -136,7 +156,7 @@ func TestValidateCandidate(t *testing.T) {
 			default:
 				assert.NilError(t, err)
 				assert.Equal(t, metadata.NamePrefix+p.Name, goodPluginName)
-				assert.Equal(t, p.SchemaVersion, "0.1.0")
+				assert.Equal(t, p.SchemaVersion, tc.expVer)
 				assert.Equal(t, p.Vendor, "e2e-testing")
 			}
 		})

cli-plugins/manager/plugin.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strconv"
 	"strings"
 
 	"github.com/docker/cli/cli-plugins/metadata"
@@ -115,8 +116,8 @@ func newPlugin(c pluginCandidate, cmds []*cobra.Command) (Plugin, error) {
 		p.Err = wrapAsPluginError(err, "invalid metadata")
 		return p, nil
 	}
-	if p.Metadata.SchemaVersion != "0.1.0" {
-		p.Err = newPluginError("plugin SchemaVersion %q is not valid, must be 0.1.0", p.Metadata.SchemaVersion)
+	if err := validateSchemaVersion(p.Metadata.SchemaVersion); err != nil {
+		p.Err = &pluginError{cause: err}
 		return p, nil
 	}
 	if p.Metadata.Vendor == "" {
@@ -126,6 +127,31 @@ func newPlugin(c pluginCandidate, cmds []*cobra.Command) (Plugin, error) {
 	return p, nil
 }
 
+// validateSchemaVersion validates if the plugin's schemaVersion is supported.
+//
+// The current schema-version is "0.1.0", but we don't want to break compatibility
+// until v2.0.0 of the schema version. Check for the major version to be < 2.0.0.
+//
+// Note that CLI versions before 28.4.1 may not support these versions as they were
+// hard-coded to only accept "0.1.0".
+func validateSchemaVersion(version string) error {
+	if version == "0.1.0" {
+		return nil
+	}
+	if version == "" {
+		return errors.New("plugin SchemaVersion version cannot be empty")
+	}
+	major, _, ok := strings.Cut(version, ".")
+	majorVersion, err := strconv.Atoi(major)
+	if !ok || err != nil {
+		return fmt.Errorf("plugin SchemaVersion %q has wrong format: must be <major>.<minor>.<patch>", version)
+	}
+	if majorVersion > 1 {
+		return fmt.Errorf("plugin SchemaVersion %q is not supported: must be lower than 2.0.0", version)
+	}
+	return nil
+}
+
 // RunHook executes the plugin's hooks command
 // and returns its unprocessed output.
 func (p *Plugin) RunHook(ctx context.Context, hookData HookPluginData) ([]byte, error) {