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

[Serge Hallyn]

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.

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.