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>

Conflicts:
	integration-cli/docker_cli_start_test.go
		cli integration test
Upstream-commit: 967f80f3cceb96f85a4795d42eeb7b84ae0ce24a
Component: engine

components/engine/daemon/volumes.go

@@ -191,15 +191,20 @@ 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

@@ -2,6 +2,7 @@ package main
 
 import (
 	"os/exec"
+	"strings"
 	"testing"
 	"time"
 )
@@ -36,3 +37,31 @@ func TestStartAttachReturnsOnError(t *testing.T) {
 
 	logDone("start - error on start with attach exits")
 }
+
+// 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")
+}