[lxc-devel] [PATCH v3] Add lxc-copy executable

[Christian Brauner]

On Mon, Nov 09, 2015 at 07:55:31PM +0000, Serge Hallyn wrote:
> Quoting Christian Brauner (christianvanbrauner at gmail.com):
> > This is a complete reimplementation of lxc-clone and lxc-start-ephemeral.
> > lxc-copy merges the functionalities of lxc-clone + lxc-start-ephemeral.
> > 
> > (1) Cloning containers:
> > 
> > 	(a) as copy:
> > 
> > 		lxc-copy -n aa -N bb
> > 
> > 	(b) as snapshot:
> > 
> > 		lxc-copy -n aa -N bb -s
> > 
> > (2) Renaming containers:
> > 
> > 	lxc-copy -n aa -N bb -R
> > 
> > (3) Starting ephemeral containers:
> > 
> > Ephemeral containers are created and started by passing the flag -e /
> > --ephemeral. Whenever this flag is missing a copy of the container is created.
> > The flag -e / --ephemeral implies -s / --snapshot.
> > 
> > 	(a) start ephemeral container daemonized with random name:
> > 
> > 		lxc-copy -n aa -e
> > 
> > 	(b) start ephemeral container in foreground mode with random name:
> > 
> > 		lxc-copy -n aa -e -F
> > 
> > 	(c) start ephemeral container with specified name in daemonized mode:
> > 	    Analogous to lxc-start ephemeral containers start in daemonized
> >             mode per default:
> > 
> > 		lxc-copy -n aa -N bb -e
> > 
> > 	    One can however also explicitly pass -d / --daemon:
> > 
> > 		lxc-copy -n aa -N bb -e -d
> > 
> > 	    but both commands are equivalent.
> > 
> > 	(d) start non-ephemeral container in daemonized mode:
> > 
> > 		lxc-copy -n aa -D -e
> > 
> > 	(e) start ephemeral container in daemonized mode and keep the original
> > 	    hostname:
> > 
> > 		lxc-copy -n aa -K -e
> > 
> > 	(f) start ephemeral container in daemonized mode and keep the
> > 	    MAC-address of the original container:
> > 
> > 		lxc-copy -n aa -M -e
> > 
> > 	(g) start ephemeral container with custom mounts (additional mounts can
> >             be of type {bind,aufs,overlay}) in daemonized mode:
> > 
> > 		lxc-copy -n aa -e -m bind=/src:/dest:ro,aufs=/src:/dest,overlay=/src:/dest
> > 
> > (4) Other options:
> > 
> > 	lxc-copy --help
> > 
> > In order to create a random containername and random upper- and workdirs for
> > custom mounts we use mkdtemp() to not just create the names but also directly
> > create the corresponding directories. This will be safer and make the code
> > considerably shorter.
> > 
> > Signed-off-by: Christian Brauner <christianvanbrauner at gmail.com>
> > ---
> >  src/lxc/Makefile.am |   2 +
> >  src/lxc/arguments.h |   2 +
> >  src/lxc/lxc_copy.c  | 744 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 748 insertions(+)
> >  create mode 100644 src/lxc/lxc_copy.c
> > 
> > diff --git a/src/lxc/Makefile.am b/src/lxc/Makefile.am
> > index ce46495..72f1e9b 100644
> > --- a/src/lxc/Makefile.am
> > +++ b/src/lxc/Makefile.am
> > @@ -183,6 +183,7 @@ bin_PROGRAMS = \
> >  	lxc-cgroup \
> >  	lxc-checkpoint \
> >  	lxc-clone \
> > +	lxc-copy \
> >  	lxc-config \
> >  	lxc-console \
> >  	lxc-create \
> > @@ -226,6 +227,7 @@ init_lxc_SOURCES = lxc_init.c
> >  lxc_monitor_SOURCES = lxc_monitor.c
> >  lxc_monitord_SOURCES = lxc_monitord.c
> >  lxc_clone_SOURCES = lxc_clone.c
> > +lxc_copy_SOURCES = lxc_copy.c
> >  lxc_start_SOURCES = lxc_start.c
> >  lxc_stop_SOURCES = lxc_stop.c
> >  lxc_top_SOURCES = lxc_top.c
> > diff --git a/src/lxc/arguments.h b/src/lxc/arguments.h
> > index bf03dc5..c261935 100644
> > --- a/src/lxc/arguments.h
> > +++ b/src/lxc/arguments.h
> > @@ -100,6 +100,7 @@ struct lxc_arguments {
> >  
> >  	/* lxc-snapshot and lxc-clone */
> >  	enum task {
> > +		CLONE,
> >  		DESTROY,
> >  		LIST,
> >  		RESTORE,
> > @@ -111,6 +112,7 @@ struct lxc_arguments {
> >  	char *newname;
> >  	char *newpath;
> >  	char *snapname;
> > +	int keepdata;
> >  	int keepname;
> >  	int keepmac;
> >  
> > diff --git a/src/lxc/lxc_copy.c b/src/lxc/lxc_copy.c
> > new file mode 100644
> > index 0000000..ac1b051
> > --- /dev/null
> > +++ b/src/lxc/lxc_copy.c
> > @@ -0,0 +1,744 @@
> > +/*
> > + *
> > + * Copyright © 2015 Christian Brauner <christianvanbrauner at gmail.com>.
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2, 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, write to the Free Software Foundation, Inc.,
> > + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
> > + */
> > +
> > +#define _GNU_SOURCE
> > +#include <unistd.h>
> > +#include <getopt.h>
> > +#include <signal.h>
> > +#include <stdio.h>
> > +#include <sys/types.h>
> > +#include <stdint.h>
> > +#include <sys/wait.h>
> > +#include <stdlib.h>
> > +#include <errno.h>
> > +#include <ctype.h>
> > +#include <sys/stat.h>
> > +#include <fcntl.h>
> > +#include <time.h>
> > +#include <stdbool.h>
> > +
> > +#include <lxc/lxccontainer.h>
> > +
> > +#include "attach.h"
> > +#include "log.h"
> > +#include "confile.h"
> > +#include "arguments.h"
> > +#include "lxc.h"
> > +#include "conf.h"
> > +#include "state.h"
> > +#include "utils.h"
> > +#include "bdev.h"
> > +
> > +lxc_log_define(lxc_copy_ui, lxc);
> > +
> > +enum mnttype {
> > +	LXC_MNT_BIND,
> > +	LXC_MNT_AUFS,
> > +	LXC_MNT_OVL,
> > +};
> > +
> > +struct mnts {
> > +	enum mnttype type;
> > +	char *src;
> > +	char *dest;
> > +	char *options;
> > +	char *upper;
> > +	char *workdir;
> > +	char *lower;
> > +};
> > +
> > +static unsigned int num = 0;
> 
> Looks good, thanks.
> 
> One weird thing here is that num is a global but you pass a pointer to it
> into some functions.  But let's go with this patch as is.
I have a bugfix in line anyway and I'll change it on the way.

> 
> Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>
> 
> However, let's say loudly and clearly that we are not yet committed to this
> precise API - we may want to make some changes as people get experience with
> it.
Let's say loudly and clearly now that I assumed this from the start. :)