Fix: Failed Start breaks VolumesFrom

Running parseVolumesFromSpec on all VolumesFrom specs before initialize
any mounts endures that we don't leave container.Volumes in an
inconsistent (partially initialized) if one of out mount groups is not
available (e.g. the container we're trying to mount from does not
exist).

Keeping container.Volumes in a consistent state ensures that next time
we Start() the container, it'll run prepareVolumes() again.

The attached test demonstrates that when a container fails to start due
to a missing container specified in VolumesFrom, it "remembers" a Volume
that worked.

Fixes: #8726

Signed-off-by: Thomas Orozco <thomas@orozco.fr>
Upstream-commit: fb62e184412b6d2bf38975a7051738f05b1f413d
Component: engine

components/engine/daemon/volumes.go

@@ -204,15 +204,20 @@ func parseBindMountSpec(spec string) (string, string, bool, error) {
 func (container *Container) applyVolumesFrom() error {
 	volumesFrom := container.hostConfig.VolumesFrom
 
+	mountGroups := make([]map[string]*Mount, 0, len(volumesFrom))
+
 	for _, spec := range volumesFrom {
-		mounts, err := parseVolumesFromSpec(container.daemon, spec)
+		mountGroup, err := parseVolumesFromSpec(container.daemon, spec)
 		if err != nil {
 			return err
 		}
+		mountGroups = append(mountGroups, mountGroup)
+	}
 
+	for _, mounts := range mountGroups {
 		for _, mnt := range mounts {
 			mnt.container = container
-			if err = mnt.initialize(); err != nil {
+			if err := mnt.initialize(); err != nil {
 				return err
 			}
 		}

components/engine/integration-cli/docker_cli_start_test.go

@@ -109,3 +109,31 @@ func TestStartRecordError(t *testing.T) {
 
 	logDone("start - set state error when start fails")
 }
+
+// gh#8726: a failed Start() breaks --volumes-from on subsequent Start()'s
+func TestStartVolumesFromFailsCleanly(t *testing.T) {
+	defer deleteAllContainers()
+
+	// Create the first data volume
+	cmd(t, "run", "-d", "--name", "data_before", "-v", "/foo", "busybox")
+
+	// Expect this to fail because the data test after contaienr doesn't exist yet
+	if _, err := runCommand(exec.Command(dockerBinary, "run", "-d", "--name", "consumer", "--volumes-from", "data_before", "--volumes-from", "data_after", "busybox")); err == nil {
+		t.Fatal("Expected error but got none")
+	}
+
+	// Create the second data volume
+	cmd(t, "run", "-d", "--name", "data_after", "-v", "/bar", "busybox")
+
+	// Now, all the volumes should be there
+	cmd(t, "start", "consumer")
+
+	// Check that we have the volumes we want
+	out, _, _ := cmd(t, "inspect", "--format='{{ len .Volumes }}'", "consumer")
+	n_volumes := strings.Trim(out, " \r\n'")
+	if n_volumes != "2" {
+		t.Fatalf("Missing volumes: expected 2, got %s", n_volumes)
+	}
+
+	logDone("start - missing containers in --volumes-from did not affect subsequent runs")
+}