Merge lp:~sidnei/golxc/clone-with-backing-store into lp:golxc

[Sidnei da Silva]

Suport extra args for lxc-clone in lxc 1.0alpha2

Allow using snapshots for cloning, selecting a specific backing store and also
passing template arguments to whatever template was used when cloning.

[Sidnei da Silva (sidnei)]

Please take a look.

[John A Meinel (jameinel)]

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On 2013-10-23 2:29, Sidnei da Silva wrote:
> Sidnei da Silva has proposed merging
> lp:~sidnei/golxc/clone-with-backing-store into lp:golxc.
>
> Requested reviews: juju hackers (juju) Related bugs: Bug #1203291
> in juju-core: "local provider moar awesome with lxc-clone"
> https://bugs.launchpad.net/juju-core/+bug/1203291
>
> For more details, see:
> https://code.launchpad.net/~sidnei/golxc/clone-with-backing-store/+merge/180444
>
> Suport extra args for lxc-clone in lxc 0.9
>
> Allow using snapshots for cloning, selecting a specific backing
> store and also passing template arguments to whatever template was
> used when cloning.
>

Is this backwards compatible for the version of LXC that is default
installed in Precise?

Can it be made to be that way?

John
=:->

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[Sidnei da Silva (sidnei)]

On Tue, Nov 5, 2013 at 5:36 AM, John A Meinel <email address hidden>wrote:

>
> Is this backwards compatible for the version of LXC that is default
> installed in Precise?
>
> Can it be made to be that way?
>

It isn't because there's extra arguments that weren't there before. It
could be made compatible by sniffing out valid arguments from lxc-create
--help and lxc-clone --help, but I feel that could be too fragile. My
understanding is that lxc would be backported into the cloud archive all
the way to precise, but maybe that's not the case?

--
Sidnei

Make the most of Ubuntu with Ubuntu One
http://one.ubuntu.com

Unmerged revisions

9. By Sidnei da Silva on 2013-10-22

- Don't conditionally set options

8. By Sidnei da Silva on 2013-08-20

- Expose more settings via create and clone

7. By Sidnei da Silva on 2013-08-15

- Some test tweaks

6. By Sidnei da Silva on 2013-08-15

- Initial attempt with simply modifying the interface in place, better advice to come.

=== modified file 'golxc.go'
--- golxc.go	2013-06-14 01:27:52 +0000
+++ golxc.go	2013-10-22 22:26:14 +0000
@@ -57,6 +57,18 @@
 	LogFatal    LogLevel = "FATAL"
 )
 
+// BackingStore represents a container's backing store when cloning.
+type BackingStore string
+
+const (
+	BackingStoreAuto      BackingStore = "auto"
+	BackingStoreLVM       BackingStore = "lvm"
+	BackingStoreBTRFS     BackingStore = "btrfs"
+	BackingStoreOverlayFS BackingStore = "overlayfs"
+	BackingStoreDir       BackingStore = "dir"
+	BackingStoreLoop      BackingStore = "loop"
+)
+
 // Container represents a linux container instance and provides
 // operations to create, maintain and destroy the container.
 type Container interface {
@@ -65,16 +77,16 @@
 	Name() string
 
 	// Create creates a new container based on the given template.
-	Create(configFile, template string, templateArgs ...string) error
+	Create(configFile string, backingStore BackingStore, fsSize string, fsType string, template string, templateArgs ...string) error
 
 	// Start runs the container as a daemon.
-	Start(configFile, consoleFile string) error
+	Start(configFile string, consoleFile string) error
 
 	// Stop terminates the running container.
 	Stop() error
 
 	// Clone creates a copy of the container, giving the copy the specified name.
-	Clone(name string) (Container, error)
+	Clone(name string, snapshot bool, backingStore BackingStore, fsSize string, templateArgs ...string) (Container, error)
 
 	// Freeze freezes all the container's processes.
 	Freeze() error
@@ -179,7 +191,7 @@
 }
 
 // Create creates a new container based on the given template.
-func (c *container) Create(configFile, template string, templateArgs ...string) error {
+func (c *container) Create(configFile string, backingStore BackingStore, fsSize string, fsType string, template string, templateArgs ...string) error {
 	if c.IsConstructed() {
 		return fmt.Errorf("container %q is already created", c.Name())
 	}
@@ -190,8 +202,19 @@
 	if configFile != "" {
 		args = append(args, "-f", configFile)
 	}
-	args = append(args, "--")
+	if backingStore != BackingStoreAuto {
+		args = append(args, "-B", string(backingStore))
+	} else {
+		args = append(args, "-B", "best")
+	}
+	if fsSize != "" {
+		args = append(args, "--fssize", fsSize)
+	}
+	if fsType != "" {
+		args = append(args, "--fstype", fsType)
+	}
 	if len(templateArgs) != 0 {
+		args = append(args, "--")
 		args = append(args, templateArgs...)
 	}
 	_, err := run("lxc-create", args...)
@@ -245,7 +268,7 @@
 }
 
 // Clone creates a copy of the container, it gets the given name.
-func (c *container) Clone(name string) (Container, error) {
+func (c *container) Clone(name string, snapshot bool, backingStore BackingStore, fsSize string, templateArgs ...string) (Container, error) {
 	if !c.IsConstructed() {
 		return nil, fmt.Errorf("container %q is not yet created", c.name)
 	}
@@ -259,6 +282,19 @@
 		"-o", c.name,
 		"-n", name,
 	}
+	if snapshot {
+		args = append(args, "-s")
+	}
+	if backingStore != BackingStoreAuto {
+		args = append(args, "-B", string(backingStore))
+	}
+	if fsSize != "" {
+		args = append(args, "-L", fsSize)
+	}
+	if len(templateArgs) != 0 {
+		args = append(args, "--")
+		args = append(args, templateArgs...)
+	}
 	_, err := run("lxc-clone", args...)
 	if err != nil {
 		return nil, err

=== modified file 'golxc_test.go'
--- golxc_test.go	2013-06-14 03:27:43 +0000
+++ golxc_test.go	2013-10-22 22:26:14 +0000
@@ -16,7 +16,7 @@
 var lxcfile = `# MIRROR to be used by ubuntu template at container creation:
 # Leaving it undefined is fine
 #MIRROR="http://archive.ubuntu.com/ubuntu"
-# or 
+# or
 #MIRROR="http://<host-ip-addr>:3142/archive.ubuntu.com/ubuntu"
 
 # LXC_AUTO - whether or not to start containers symlinked under
@@ -232,7 +232,31 @@
 	}()
 	lcs, _ := s.factory.List()
 	oldLen := len(lcs)
-	lc2, err := lc1.Clone("golxcclone")
+	lc2, err := lc1.Clone("golxcclone", false, golxc.BackingStoreAuto)
+	c.Assert(err, IsNil)
+	c.Assert(lc2.IsConstructed(), Equals, true)
+	defer func() {
+		c.Assert(lc2.Destroy(), IsNil)
+	}()
+	lcs, _ = s.factory.List()
+	newLen := len(lcs)
+	c.Assert(newLen == oldLen+1, Equals, true)
+	c.Assert(contains(lcs, lc1), Equals, true)
+	c.Assert(contains(lcs, lc2), Equals, true)
+}
+
+func (s *LXCSuite) TestCloneSnapshotWithOverlayFS(c *C) {
+	// Test the cloning of an existing container.
+	lc1 := s.factory.New("golxc")
+	c.Assert(lc1.IsConstructed(), Equals, false)
+	c.Assert(lc1.Create("", "ubuntu"), IsNil)
+	c.Assert(lc1.IsConstructed(), Equals, true)
+	defer func() {
+		c.Assert(lc1.Destroy(), IsNil)
+	}()
+	lcs, _ := s.factory.List()
+	oldLen := len(lcs)
+	lc2, err := lc1.Clone("golxcclone", true, golxc.BackingStoreOverlayFS)
 	c.Assert(err, IsNil)
 	c.Assert(lc2.IsConstructed(), Equals, true)
 	defer func() {
@@ -249,7 +273,7 @@
 	// Test the cloning of a non-existing container.
 	lc := s.factory.New("golxc")
 	c.Assert(lc.IsConstructed(), Equals, false)
-	_, err := lc.Clone("golxcclone")
+	_, err := lc.Clone("golxcclone", false, golxc.BackingStoreAuto)
 	c.Assert(err, ErrorMatches, "container .* is not yet created")
 }
 

=== modified file 'network.go'
--- network.go	2013-06-14 00:29:08 +0000
+++ network.go	2013-10-22 22:26:14 +0000
@@ -53,7 +53,7 @@
 	return status == "running", nil
 }
 
-// NetworkAttributes returns the lxc network attributes: 
+// NetworkAttributes returns the lxc network attributes:
 // starting IP address and bridge name.
 func NetworkAttributes() (addr, bridge string, err error) {
 	config, err := ReadConf()