overlord/snapstate: add dynamic snapdX.Y assumes

cmd/version.go

@@ -23,3 +23,9 @@ package cmd
 
 // Version will be overwritten at build-time via mkversion.sh
 var Version = "unknown"
+
+func MockVersion(version string) (restore func()) {
+	old := Version
+	Version = version
+	return func() { Version = old }
+}

overlord/snapstate/check_snap.go

@@ -21,9 +21,12 @@ package snapstate
 
 import (
 	"fmt"
+	"regexp"
+	"strconv"
 	"strings"
 
 	"github.com/snapcore/snapd/arch"
+	"github.com/snapcore/snapd/cmd"
 	"github.com/snapcore/snapd/overlord/snapstate/backend"
 	"github.com/snapcore/snapd/overlord/state"
 	"github.com/snapcore/snapd/release"
@@ -42,16 +45,60 @@ var featureSet = map[string]bool{
 func checkAssumes(s *snap.Info) error {
 	missing := ([]string)(nil)
 	for _, flag := range s.Assumes {
+		if strings.HasPrefix(flag, "snapd") && checkVersion(flag[5:]) {
+			continue
+		}
 		if !featureSet[flag] {
 			missing = append(missing, flag)
 		}
 	}
 	if len(missing) > 0 {
-		return fmt.Errorf("snap %q assumes unsupported features: %s (try new ubuntu-core)", s.Name(), strings.Join(missing, ", "))
+		hint := "try to refresh the core snap"
+		if release.OnClassic {
+			hint = "try to update snapd and refresh the core snap"
+		}
+		return fmt.Errorf("snap %q assumes unsupported features: %s (%s)", s.Name(), strings.Join(missing, ", "), hint)
 	}
 	return nil
 }
 
+var versionExp = regexp.MustCompile(`^([1-9][0-9]*)(?:\.([0-9]+)(?:\.([0-9]+))?)?`)
+
+func checkVersion(version string) bool {
+	req := versionExp.FindStringSubmatch(version)
+	if req == nil || req[0] != version {
+		return false
+	}
+
+	if cmd.Version == "unknown" {
+		return true // Development tree.
+	}
+
+	cur := versionExp.FindStringSubmatch(cmd.Version)
+	if cur == nil {
+		return false
+	}
+
+	for i := 1; i < len(req); i++ {
+		if req[i] == "" {
+			return true
+		}
+		if cur[i] == "" {
+			return false
+		}
+		reqN, err1 := strconv.Atoi(req[i])
+		curN, err2 := strconv.Atoi(cur[i])
+		if err1 != nil || err2 != nil {
+			panic("internal error: version regexp is broken")
+		}
+		if curN != reqN {
+			return curN > reqN
+		}
+	}
+
+	return true
+}
+
 var openSnapFile = backend.OpenSnapFile
 
 // checkSnap ensures that the snap can be installed.

overlord/snapstate/check_snap_test.go

@@ -26,6 +26,7 @@ import (
 	. "gopkg.in/check.v1"
 
 	"github.com/snapcore/snapd/arch"
+	"github.com/snapcore/snapd/cmd"
 	"github.com/snapcore/snapd/dirs"
 	"github.com/snapcore/snapd/overlord/state"
 	"github.com/snapcore/snapd/release"
@@ -74,40 +75,97 @@ architectures:
 	c.Assert(err.Error(), Equals, errorMsg)
 }
 
-func (s *checkSnapSuite) TestCheckSnapInstallMissingAssumes(c *C) {
-	const yaml = `name: foo
-version: 1.0
-assumes: [f1, f2]`
-
-	info, err := snap.InfoFromSnapYaml([]byte(yaml))
-	c.Assert(err, IsNil)
-
-	var openSnapFile = func(path string, si *snap.SideInfo) (*snap.Info, snap.Container, error) {
-		return info, nil, nil
-	}
-	restore := snapstate.MockOpenSnapFile(openSnapFile)
+var assumesTests = []struct {
+	version string
+	assumes string
+	classic bool
+	error   string
+}{{
+	assumes: "[common-data-dir]",
+}, {
+	assumes: "[f1, f2]",
+	error:   `snap "foo" assumes unsupported features: f1, f2 \(try to refresh the core snap\)`,
+}, {
+	assumes: "[f1, f2]",
+	classic: true,
+	error:   `snap "foo" assumes unsupported features: f1, f2 \(try to update snapd and refresh the core snap\)`,
+}, {
+	assumes: "[snapd2.15]",
+	version: "unknown",
+}, {
+	assumes: "[snapdnono]",
+	version: "unknown",
+	error:   `.* unsupported features: snapdnono .*`,
+}, {
+	assumes: "[snapd2.15nono]",
+	version: "unknown",
+	error:   `.* unsupported features: snapd2.15nono .*`,
+}, {
+	assumes: "[snapd2.15]",
+	version: "2.15",
+}, {
+	assumes: "[snapd2.15]",
+	version: "2.15.1",
+}, {
+	assumes: "[snapd2.15]",
+	version: "2.15+git",
+}, {
+	assumes: "[snapd2.15]",
+	version: "2.16",
+}, {
+	assumes: "[snapd2.15.1]",
+	version: "2.16",
+}, {
+	assumes: "[snapd2.15.2]",
+	version: "2.16.1",
+}, {
+	assumes: "[snapd3]",
+	version: "3.1",
+}, {
+	assumes: "[snapd2.16]",
+	version: "2.15",
+	error:   `.* unsupported features: snapd2\.16 .*`,
+}, {
+	assumes: "[snapd2.15.1]",
+	version: "2.15",
+	error:   `.* unsupported features: snapd2\.15\.1 .*`,
+}, {
+	assumes: "[snapd2.15.1]",
+	version: "2.15.0",
+	error:   `.* unsupported features: snapd2\.15\.1 .*`,
+}}
+
+func (s *checkSnapSuite) TestCheckSnapAssumes(c *C) {
+	restore := cmd.MockVersion("2.15")
 	defer restore()
 
-	err = snapstate.CheckSnap(s.st, "snap-path", nil, nil, snapstate.Flags{})
-	c.Check(err, ErrorMatches, `snap "foo" assumes unsupported features: f1, f2.*`)
-}
-
-func (s *checkSnapSuite) TestCheckSnapInstallProvidedAssumes(c *C) {
-	const yaml = `name: foo
-version: 1.0
-assumes: [common-data-dir]`
-
-	info, err := snap.InfoFromSnapYaml([]byte(yaml))
-	c.Assert(err, IsNil)
-
-	var openSnapFile = func(path string, si *snap.SideInfo) (*snap.Info, snap.Container, error) {
-		return info, nil, nil
-	}
-	restore := snapstate.MockOpenSnapFile(openSnapFile)
+	restore = release.MockOnClassic(false)
 	defer restore()
 
-	err = snapstate.CheckSnap(s.st, "snap-path", nil, nil, snapstate.Flags{})
-	c.Check(err, IsNil)
+	for _, test := range assumesTests {
+		cmd.Version = test.version
+		if cmd.Version == "" {
+			cmd.Version = "2.15"
+		}
+		release.OnClassic = test.classic
+
+		yaml := fmt.Sprintf("name: foo\nversion: 1.0\nassumes: %s\n", test.assumes)
+
+		info, err := snap.InfoFromSnapYaml([]byte(yaml))
+		c.Assert(err, IsNil)
+
+		var openSnapFile = func(path string, si *snap.SideInfo) (*snap.Info, snap.Container, error) {
+			return info, nil, nil
+		}
+		restore := snapstate.MockOpenSnapFile(openSnapFile)
+		defer restore()
+		err = snapstate.CheckSnap(s.st, "snap-path", nil, nil, snapstate.Flags{})
+		if test.error != "" {
+			c.Check(err, ErrorMatches, test.error)
+		} else {
+			c.Assert(err, IsNil)
+		}
+	}
 }
 
 func (s *checkSnapSuite) TestCheckSnapCheckCallbackOK(c *C) {