On 05/15/2013 10:23 AM, Serge Hallyn wrote:
> Add a clone hook called from api_clone. Pass arguments to it from
> lxc_clone.c.
>
> The clone update hook is called while the container's bdev is mounted.
> Information about the container is passed in through environment
> variables LXC_ROOTFS_PATH, LXC_NAME, The LXC_ROOTFS_MOUNT, and
> LXC_CONFIG_FILE.
>
> LXC_ROOTFS_MOUNT=/usr/lib/x86_64-linux-gnu/lxc
> LXC_CONFIG_FILE=/var/lib/lxc/demo3/config
> LXC_ROOTFS_PATH=/var/lib/lxc/demo3/rootfs
> LXC_NAME=demo3
>
> So from the hook, updates to the container should be made under
> $LXC_ROOTFS_MOUNT/ .
>
> The hook also receives command line arguments as follows:
> First argument is container name, second is always 'lxc', third
> is the hook name (always clone), then come the arguments which
> were passed to lxc-clone. I.e. when I did:
>
> sudo lxc-clone demo2 demo3 -- hey there dude
>
> the arguments passed in were "demo3 lxc clone hey there dude"
>
> I personally would like to drop the first two arguments. The
> name is available as $LXC_NAME, and the section argument ('lxc')
> is meaningless. However, doing so risks invalidating existing
> hooks.
>
> Soon analogous create and destroy hooks will be added as well.
I think I'd have preferred storing the command arguments in
LXC_CLONE_ARGS instead of directly in argv. Doing so would allow us to
remove/add other arguments without breaking all existing hooks.
The user could then do "set -- $LXC_CLONE_ARGS" and just use $1... as usual.
But I'm not horribly opposed to the proposed implementation and the rest
looks good.
Acked-by: Stéphane Graber <stgra...@ubuntu.com>
> Signed-off-by: Serge Hallyn <serge.hal...@ubuntu.com>
> ---
> src/lxc/conf.c | 63
> +++++++++++++++++++++++++++++++++++++++++++++-----
> src/lxc/conf.h | 4 ++--
> src/lxc/confile.c | 3 +++
> src/lxc/lxc_clone.c | 16 ++++++-------
> src/lxc/lxccontainer.c | 55 ++++++++++++++++++++++++++++++-------------
> src/lxc/lxccontainer.h | 2 +-
> src/lxc/start.c | 6 ++---
> 7 files changed, 113 insertions(+), 36 deletions(-)
>
> diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> index 746a2db..61e45b1 100644
> --- a/src/lxc/conf.c
> +++ b/src/lxc/conf.c
> @@ -173,7 +173,7 @@ return -1;
> #endif
>
> char *lxchook_names[NUM_LXC_HOOKS] = {
> - "pre-start", "pre-mount", "mount", "autodev", "start", "post-stop" };
> + "pre-start", "pre-mount", "mount", "autodev", "start", "post-stop",
> "clone" };
>
> typedef int (*instanciate_cb)(struct lxc_handler *, struct lxc_netdev *);
>
> @@ -336,6 +336,55 @@ static int run_buffer(char *buffer)
> return 0;
> }
>
> +static int run_script_argv(const char *name, const char *section,
> + const char *script, const char *hook, char **argsin)
> +{
> + int ret, i;
> + char *buffer;
> + size_t size = 0;
> +
> + INFO("Executing script '%s' for container '%s', config section '%s'",
> + script, name, section);
> +
> + for (i=0; argsin && argsin[i]; i++)
> + size += strlen(argsin[i]) + 1;
> +
> + size += strlen(hook) + 1;
> +
> + size += strlen(script);
> + size += strlen(name);
> + size += strlen(section);
> + size += 3;
> +
> + if (size > INT_MAX)
> + return -1;
> +
> + buffer = alloca(size);
> + if (!buffer) {
> + ERROR("failed to allocate memory");
> + return -1;
> + }
> +
> + ret = snprintf(buffer, size, "%s %s %s %s", script, name, section,
> hook);
> + if (ret < 0 || ret >= size) {
> + ERROR("Script name too long");
> + return -1;
> + }
> +
> + for (i=0; argsin && argsin[i]; i++) {
> + int len = size-ret;
> + int rc;
> + rc = snprintf(buffer + ret, len, " %s", argsin[i]);
> + if (rc < 0 || rc >= len) {
> + ERROR("Script args too long");
> + return -1;
> + }
> + ret += rc;
> + }
> +
> + return run_buffer(buffer);
> +}
> +
> static int run_script(const char *name, const char *section,
> const char *script, ...)
> {
> @@ -2752,7 +2801,7 @@ int lxc_setup(const char *name, struct lxc_conf
> *lxc_conf)
> return -1;
> }
>
> - if (run_lxc_hooks(name, "pre-mount", lxc_conf)) {
> + if (run_lxc_hooks(name, "pre-mount", lxc_conf, NULL)) {
> ERROR("failed to run pre-mount hooks for container '%s'.",
> name);
> return -1;
> }
> @@ -2779,13 +2828,13 @@ int lxc_setup(const char *name, struct lxc_conf
> *lxc_conf)
> return -1;
> }
>
> - if (run_lxc_hooks(name, "mount", lxc_conf)) {
> + if (run_lxc_hooks(name, "mount", lxc_conf, NULL)) {
> ERROR("failed to run mount hooks for container '%s'.", name);
> return -1;
> }
>
> if (lxc_conf->autodev) {
> - if (run_lxc_hooks(name, "autodev", lxc_conf)) {
> + if (run_lxc_hooks(name, "autodev", lxc_conf, NULL)) {
> ERROR("failed to run autodev hooks for container
> '%s'.", name);
> return -1;
> }
> @@ -2852,7 +2901,7 @@ int lxc_setup(const char *name, struct lxc_conf
> *lxc_conf)
> return 0;
> }
>
> -int run_lxc_hooks(const char *name, char *hook, struct lxc_conf *conf)
> +int run_lxc_hooks(const char *name, char *hook, struct lxc_conf *conf, char
> *argv[])
> {
> int which = -1;
> struct lxc_list *it;
> @@ -2869,12 +2918,14 @@ int run_lxc_hooks(const char *name, char *hook,
> struct lxc_conf *conf)
> which = LXCHOOK_START;
> else if (strcmp(hook, "post-stop") == 0)
> which = LXCHOOK_POSTSTOP;
> + else if (strcmp(hook, "clone") == 0)
> + which = LXCHOOK_CLONE;
> else
> return -1;
> lxc_list_for_each(it, &conf->hooks[which]) {
> int ret;
> char *hookname = it->elem;
> - ret = run_script(name, "lxc", hookname, hook, NULL);
> + ret = run_script_argv(name, "lxc", hookname, hook, argv);
> if (ret)
> return ret;
> }
> diff --git a/src/lxc/conf.h b/src/lxc/conf.h
> index 465b1ec..5139aa3 100644
> --- a/src/lxc/conf.h
> +++ b/src/lxc/conf.h
> @@ -237,7 +237,7 @@ struct lxc_rootfs {
> */
> enum lxchooks {
> LXCHOOK_PRESTART, LXCHOOK_PREMOUNT, LXCHOOK_MOUNT, LXCHOOK_AUTODEV,
> - LXCHOOK_START, LXCHOOK_POSTSTOP, NUM_LXC_HOOKS};
> + LXCHOOK_START, LXCHOOK_POSTSTOP, LXCHOOK_CLONE, NUM_LXC_HOOKS};
> extern char *lxchook_names[NUM_LXC_HOOKS];
>
> struct saved_nic {
> @@ -284,7 +284,7 @@ struct lxc_conf {
> char *rcfile; // Copy of the top level rcfile we read
> };
>
> -int run_lxc_hooks(const char *name, char *hook, struct lxc_conf *conf);
> +int run_lxc_hooks(const char *name, char *hook, struct lxc_conf *conf, char
> *argv[]);
>
> extern int setup_cgroup(const char *cgpath, struct lxc_list *cgroups);
> extern int detect_shared_rootfs(void);
> diff --git a/src/lxc/confile.c b/src/lxc/confile.c
> index aec8177..fb851c9 100644
> --- a/src/lxc/confile.c
> +++ b/src/lxc/confile.c
> @@ -117,6 +117,7 @@ static struct lxc_config_t config[] = {
> { "lxc.hook.autodev", config_hook },
> { "lxc.hook.start", config_hook },
> { "lxc.hook.post-stop", config_hook },
> + { "lxc.hook.clone", config_hook },
> { "lxc.network.type", config_network_type },
> { "lxc.network.flags", config_network_flags },
> { "lxc.network.link", config_network_link },
> @@ -894,6 +895,8 @@ static int config_hook(const char *key, const char *value,
> return add_hook(lxc_conf, LXCHOOK_START, copy);
> else if (strcmp(key, "lxc.hook.post-stop") == 0)
> return add_hook(lxc_conf, LXCHOOK_POSTSTOP, copy);
> + else if (strcmp(key, "lxc.hook.clone") == 0)
> + return add_hook(lxc_conf, LXCHOOK_CLONE, copy);
> SYSERROR("Unknown key: %s", key);
> free(copy);
> return -1;
> diff --git a/src/lxc/lxc_clone.c b/src/lxc/lxc_clone.c
> index b9c7a6e..2b0ee43 100644
> --- a/src/lxc/lxc_clone.c
> +++ b/src/lxc/lxc_clone.c
> @@ -16,7 +16,7 @@
>
> lxc_log_define(lxc_clone, lxc);
>
> -void usage(char *me)
> +void usage(const char *me)
> {
> printf("Usage: %s [-s] [-B backingstore] [-L size] [-K] [-M] [-H]\n",
> me);
> printf(" [-p lxcpath] [-P newlxcpath] orig new\n");
> @@ -60,6 +60,7 @@ int main(int argc, char *argv[])
> long newsize = 0;
> char *bdevtype = NULL, *lxcpath = NULL, *newpath = NULL, *fstype = NULL;
> char *orig = NULL, *new = NULL, *vgname = NULL;
> + char **args = NULL;
> char c;
>
> if (argc < 3)
> @@ -86,14 +87,13 @@ int main(int argc, char *argv[])
> default: break;
> }
> }
> - if (optind == argc-2 && !orig)
> + if (optind < argc && !orig)
> orig = argv[optind++];
> - if (optind == argc-1 && !new)
> + if (optind < argc && !new)
> new = argv[optind++];
> - if (optind < argc) {
> - printf("%d extraneous arguments\n", argc-optind);
> - usage(argv[0]);
> - }
> + if (optind < argc)
> + /* arguments for the clone hook */
> + args = &argv[optind];
> if (!new || !orig) {
> printf("Error: you must provide orig and new names\n");
> usage(argv[0]);
> @@ -124,7 +124,7 @@ int main(int argc, char *argv[])
> lxc_container_put(c1);
> exit(1);
> }
> - c2 = c1->clone(c1, new, newpath, flags, bdevtype, NULL, newsize);
> + c2 = c1->clone(c1, new, newpath, flags, bdevtype, NULL, newsize, args);
> if (c2 == NULL) {
> lxc_container_put(c1);
> fprintf(stderr, "clone failed\n");
> diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> index bac94c2..23db6f2 100644
> --- a/src/lxc/lxccontainer.c
> +++ b/src/lxc/lxccontainer.c
> @@ -1364,16 +1364,14 @@ static int copy_storage(struct lxc_container *c0,
> struct lxc_container *c,
> return 0;
> }
>
> -static int clone_update_rootfs(struct lxc_container *c, int flags)
> +static int clone_update_rootfs(struct lxc_container *c, int flags, char
> **hookargs)
> {
> int ret = -1;
> char path[MAXPATHLEN];
> struct bdev *bdev;
> FILE *fout;
> pid_t pid;
> -
> - if (flags & LXC_CLONE_KEEPNAME)
> - return 0;
> + struct lxc_conf *conf = c->lxc_conf;
>
> /* update hostname in rootfs */
> /* we're going to mount, so run in a clean namespace to simplify
> cleanup */
> @@ -1393,17 +1391,41 @@ static int clone_update_rootfs(struct lxc_container
> *c, int flags)
> exit(1);
> if (bdev->ops->mount(bdev) < 0)
> exit(1);
> - ret = snprintf(path, MAXPATHLEN, "%s/etc/hostname", bdev->dest);
> - if (ret < 0 || ret >= MAXPATHLEN)
> - exit(1);
> - if (!(fout = fopen(path, "w"))) {
> - SYSERROR("unable to open %s: ignoring\n", path);
> - exit(0);
> +
> + if (!lxc_list_empty(&conf->hooks[LXCHOOK_CLONE])) {
> + /* Start of environment variable setup for hooks */
> + if (setenv("LXC_NAME", c->name, 1)) {
> + SYSERROR("failed to set environment variable for
> container name");
> + }
> + if (setenv("LXC_CONFIG_FILE", conf->rcfile, 1)) {
> + SYSERROR("failed to set environment variable for config
> path");
> + }
> + if (setenv("LXC_ROOTFS_MOUNT", conf->rootfs.mount, 1)) {
> + SYSERROR("failed to set environment variable for rootfs
> mount");
> + }
> + if (setenv("LXC_ROOTFS_PATH", conf->rootfs.path, 1)) {
> + SYSERROR("failed to set environment variable for rootfs
> mount");
> + }
> +
> + if (run_lxc_hooks(c->name, "clone", conf, hookargs)) {
> + ERROR("Error executing clone hook for %s", c->name);
> + exit(1);
> + }
> + }
> +
> + if (!(flags & LXC_CLONE_KEEPNAME)) {
> + ret = snprintf(path, MAXPATHLEN, "%s/etc/hostname", bdev->dest);
> + if (ret < 0 || ret >= MAXPATHLEN)
> + exit(1);
> + if (!(fout = fopen(path, "w"))) {
> + SYSERROR("unable to open %s: ignoring\n", path);
> + exit(0);
> + }
> + if (fprintf(fout, "%s", c->name) < 0)
> + exit(1);
> + if (fclose(fout) < 0)
> + exit(1);
> }
> - if (fprintf(fout, "%s", c->name) < 0)
> - exit(1);
> - if (fclose(fout) < 0)
> - exit(1);
> exit(0);
> }
>
> @@ -1436,7 +1458,8 @@ static int create_file_dirname(char *path)
>
> struct lxc_container *lxcapi_clone(struct lxc_container *c, const char
> *newname,
> const char *lxcpath, int flags,
> - const char *bdevtype, const char *bdevdata, unsigned long
> newsize)
> + const char *bdevtype, const char *bdevdata, unsigned long
> newsize,
> + char **hookargs)
> {
> struct lxc_container *c2 = NULL;
> char newpath[MAXPATHLEN];
> @@ -1525,7 +1548,7 @@ struct lxc_container *lxcapi_clone(struct lxc_container
> *c, const char *newname,
> if (!c2->save_config(c2, NULL))
> goto out;
>
> - if (clone_update_rootfs(c2, flags) < 0)
> + if (clone_update_rootfs(c2, flags, hookargs) < 0)
> goto out;
>
> // TODO: update c's lxc.snapshot = count
> diff --git a/src/lxc/lxccontainer.h b/src/lxc/lxccontainer.h
> index b6bd97c..67fbed4 100644
> --- a/src/lxc/lxccontainer.h
> +++ b/src/lxc/lxccontainer.h
> @@ -105,7 +105,7 @@ struct lxc_container {
> */
> struct lxc_container *(*clone)(struct lxc_container *c, const char
> *newname,
> const char *lxcpath, int flags, const char *bdevtype,
> - const char *bdevdata, unsigned long newsize);
> + const char *bdevdata, unsigned long newsize, char **hookargs);
>
> #if 0
> bool (*commit_cgroups)(struct lxc_container *c);
> diff --git a/src/lxc/start.c b/src/lxc/start.c
> index fd96d4f..995460e 100644
> --- a/src/lxc/start.c
> +++ b/src/lxc/start.c
> @@ -461,7 +461,7 @@ struct lxc_handler *lxc_init(const char *name, struct
> lxc_conf *conf, const char
> }
> /* End of environment variable setup for hooks */
>
> - if (run_lxc_hooks(name, "pre-start", conf)) {
> + if (run_lxc_hooks(name, "pre-start", conf, NULL)) {
> ERROR("failed to run pre-start hooks for container '%s'.",
> name);
> goto out_aborting;
> }
> @@ -513,7 +513,7 @@ static void lxc_fini(const char *name, struct lxc_handler
> *handler)
> lxc_set_state(name, handler, STOPPING);
> lxc_set_state(name, handler, STOPPED);
>
> - if (run_lxc_hooks(name, "post-stop", handler->conf))
> + if (run_lxc_hooks(name, "post-stop", handler->conf, NULL))
> ERROR("failed to run post-stop hooks for container '%s'.",
> name);
>
> /* reset mask set by setup_signal_fd */
> @@ -676,7 +676,7 @@ static int do_start(void *data)
> if (lxc_seccomp_load(handler->conf) != 0)
> goto out_warn_father;
>
> - if (run_lxc_hooks(handler->name, "start", handler->conf)) {
> + if (run_lxc_hooks(handler->name, "start", handler->conf, NULL)) {
> ERROR("failed to run start hooks for container '%s'.",
> handler->name);
> goto out_warn_father;
> }
>
--
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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