o/h/ctlcmd: add a snapctl fail command

overlord/hookstate/ctlcmd/fail.go

@@ -0,0 +1,81 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2024 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package ctlcmd
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/snapcore/snapd/features"
+	"github.com/snapcore/snapd/i18n"
+	"github.com/snapcore/snapd/overlord/registrystate"
+)
+
+type failCommand struct {
+	baseCommand
+
+	Positional struct {
+		Reason string `positional-args:"true" positional-arg-name:":<rejection-reason>"`
+	} `positional-args:"yes" required:"yes"`
+}
+
+var shortFailHelp = i18n.G("Fail a registry change")
+var longFailHelp = i18n.G(`
+The fail command rejects the registry changes currently being proposed,
+providing a reason for the rejection. It may only be used in a
+change-view-<plug> hook.
+`)
+
+func init() {
+	info := addCommand("fail", shortFailHelp, longFailHelp, func() command {
+		return &failCommand{}
+	})
+	info.hidden = true
+}
+
+func (c *failCommand) Execute(args []string) error {
+	if !features.Registries.IsEnabled() {
+		_, confName := features.Registries.ConfigOption()
+		return fmt.Errorf(`cannot use "snapctl fail" without enabling the %q feature`, confName)
+	}
+
+	ctx, err := c.ensureContext()
+	if err != nil {
+		return err
+	}
+
+	ctx.Lock()
+	defer ctx.Unlock()
+
+	if ctx.IsEphemeral() || !strings.HasPrefix(ctx.HookName(), "change-view-") {
+		return errors.New(i18n.G(`cannot use "snapctl fail" outside of a "change-view" hook`))
+	}
+
+	t, _ := ctx.Task()
+	tx, commitTask, err := registrystate.GetStoredTransaction(t)
+	if err != nil {
+		return fmt.Errorf(i18n.G("internal error: cannot get registry transaction to fail: %v"), err)
+	}
+
+	tx.Abort(ctx.InstanceName(), c.Positional.Reason)
+	commitTask.Set("registry-transaction", tx)
+	return nil
+}

overlord/hookstate/ctlcmd/fail_test.go

@@ -0,0 +1,127 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2024 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package ctlcmd_test
+
+import (
+	"os"
+
+	"gopkg.in/check.v1"
+	. "gopkg.in/check.v1"
+
+	"github.com/snapcore/snapd/dirs"
+	"github.com/snapcore/snapd/features"
+	"github.com/snapcore/snapd/i18n"
+	"github.com/snapcore/snapd/overlord/hookstate"
+	"github.com/snapcore/snapd/overlord/hookstate/ctlcmd"
+	"github.com/snapcore/snapd/overlord/registrystate"
+	"github.com/snapcore/snapd/snap"
+)
+
+func (s *registrySuite) mockRegistriesFeature(c *C) (restore func()) {
+	oldDir := dirs.FeaturesDir
+	dirs.FeaturesDir = c.MkDir()
+
+	registryCtlFile := features.Registries.ControlFile()
+	c.Assert(os.WriteFile(registryCtlFile, []byte(nil), 0644), check.IsNil)
+
+	return func() {
+		c.Assert(os.Remove(registryCtlFile), IsNil)
+		dirs.FeaturesDir = oldDir
+	}
+}
+
+func (s *registrySuite) TestFailAbortsRegistryTransaction(c *C) {
+	restore := s.mockRegistriesFeature(c)
+	defer restore()
+
+	s.state.Lock()
+	chg := s.state.NewChange("test", "")
+	commitTask := s.state.NewTask("commit-registry-tx", "")
+	chg.AddTask(commitTask)
+	tx, err := registrystate.NewTransaction(s.state, "my-acc", "my-reg")
+	c.Assert(err, IsNil)
+
+	err = tx.Set("foo", "bar")
+	c.Assert(err, IsNil)
+
+	commitTask.Set("registry-transaction", tx)
+
+	task := s.state.NewTask("run-hook", "")
+	chg.AddTask(task)
+	setup := &hookstate.HookSetup{Snap: "test-snap", Revision: snap.R(1), Hook: "change-view-plug"}
+	task.Set("commit-task", commitTask.ID())
+	s.state.Unlock()
+
+	mockContext, err := hookstate.NewContext(task, s.state, setup, s.mockHandler, "")
+	c.Assert(err, IsNil)
+
+	stdout, stderr, err := ctlcmd.Run(mockContext, []string{"fail", "don't like changes"}, 0)
+	c.Assert(err, IsNil)
+	c.Check(stdout, IsNil)
+	c.Check(stderr, IsNil)
+
+	tx = nil
+	s.state.Lock()
+	err = commitTask.Get("registry-transaction", &tx)
+	s.state.Unlock()
+	c.Assert(err, IsNil)
+
+	snap, reason := tx.AbortInfo()
+	c.Assert(reason, Equals, "don't like changes")
+	c.Assert(snap, Equals, "test-snap")
+}
+
+func (s *registrySuite) TestFailErrors(c *C) {
+	stdout, stderr, err := ctlcmd.Run(s.mockContext, []string{"fail", "reason"}, 0)
+	c.Assert(err, ErrorMatches, i18n.G(`cannot use "snapctl fail" without enabling the "experimental.registries" feature`))
+	c.Check(stdout, IsNil)
+	c.Check(stderr, IsNil)
+
+	restore := s.mockRegistriesFeature(c)
+	defer restore()
+
+	stdout, stderr, err = ctlcmd.Run(s.mockContext, []string{"fail"}, 0)
+	c.Assert(err, ErrorMatches, i18n.G("the required argument `:<rejection-reason>` was not provided"))
+	c.Check(stdout, IsNil)
+	c.Check(stderr, IsNil)
+
+	s.state.Lock()
+	task := s.state.NewTask("run-hook", "my test task")
+	setup := &hookstate.HookSetup{Snap: "test-snap", Revision: snap.R(1), Hook: "other-hook"}
+	s.state.Unlock()
+
+	s.mockContext, err = hookstate.NewContext(task, s.state, setup, s.mockHandler, "")
+	c.Assert(err, IsNil)
+
+	stdout, stderr, err = ctlcmd.Run(s.mockContext, []string{"fail", "reason"}, 0)
+	c.Assert(err, ErrorMatches, i18n.G(`cannot use "snapctl fail" outside of a "change-view" hook`))
+	c.Check(stdout, IsNil)
+	c.Check(stderr, IsNil)
+
+	setup = &hookstate.HookSetup{Snap: "test-snap", Revision: snap.R(1), Hook: "change-view-plug"}
+	s.mockContext, err = hookstate.NewContext(task, s.state, setup, s.mockHandler, "")
+	c.Assert(err, IsNil)
+
+	stdout, stderr, err = ctlcmd.Run(s.mockContext, []string{"fail", "reason"}, 0)
+	// this shouldn't happen but check we handle it well anyway
+	c.Assert(err, ErrorMatches, i18n.G("internal error: cannot get registry transaction to fail: no state entry for key \"commit-task\""))
+	c.Check(stdout, IsNil)
+	c.Check(stderr, IsNil)
+}

overlord/registrystate/transaction.go

@@ -279,8 +279,8 @@ func (t *Transaction) Data() ([]byte, error) {
 	return t.modified.Data()
 }
 
-// Abort prevents any further writes or reads to the transaction. It takes an
-// abortingSnap and reason that can be used to surface information to the user.
+// Abort prevents any further writes or reads to the transaction. It takes a
+// snap and reason that can be used to surface information to the user.
 func (t *Transaction) Abort(abortingSnap, reason string) {
 	t.mu.Lock()
 	defer t.mu.Unlock()
@@ -292,3 +292,7 @@ func (t *Transaction) Abort(abortingSnap, reason string) {
 func (t *Transaction) aborted() bool {
 	return t.abortReason != ""
 }
+
+func (t *Transaction) AbortInfo() (snap, reason string) {
+	return t.abortingSnap, t.abortReason
+}

overlord/registrystate/transaction_test.go

@@ -408,6 +408,10 @@ func (s *transactionTestSuite) TestAbortPreventsReadsAndWrites(c *C) {
 
 	tx.Abort("my-snap", "don't like the changes")
 
+	snap, reason := tx.AbortInfo()
+	c.Assert(reason, Equals, "don't like the changes")
+	c.Assert(snap, Equals, "my-snap")
+
 	err = tx.Set("foo", "bar")
 	c.Assert(err, ErrorMatches, "cannot write to aborted transaction")