SymbX/systemd
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

nspawn: add new --volatile switch for booting containers in volatile (ephemeral) mode

Browse Source 
Two modes are supported: --volatile=yes mounts only /usr into the
container, and a tmpfs as root directory. --volatile=state mounts the
full OS tree in, but overmounts /var with a tmpfs.

--volatile=yes hence boots with an unpopulated /etc and /var, starting
with pristine configuration and state.

--volatile=state hence boots with an unpopulated /var, only starting
with pristine state.
This commit is contained in:
Lennart Poettering
2014-07-04 03:24:42 +02:00
parent baa1bdf70f
commit 4d9f07b492
1 changed files with 148 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/nspawn/nspawn.c
+148 -10
View File
@@ -107,6 +107,12 @@ typedef enum LinkJournal {
LINK_GUEST
} LinkJournal;
typedef enum Volatile {
VOLATILE_NO,
VOLATILE_YES,
VOLATILE_STATE,
} Volatile;
static char *arg_directory = NULL;
static char *arg_user = NULL;
static sd_id128_t arg_uuid = {};
@@ -159,6 +165,7 @@ static bool arg_network_veth = false;
static const char *arg_network_bridge = NULL;
static unsigned long arg_personality = 0xffffffffLU;
static const char *arg_image = NULL;
static Volatile arg_volatile = VOLATILE_NO;
static int help(void) {
@@ -207,7 +214,8 @@ static int help(void) {
" --share-system Share system namespaces with host\n"
" --register=BOOLEAN Register container as machine\n"
" --keep-unit Do not register a scope for the machine, reuse\n"
" the service unit nspawn is running in\n",
" the service unit nspawn is running in\n"
" --volatile[=MODE] Run the system in volatile mode\n",
program_invocation_short_name);
return 0;
@@ -235,6 +243,7 @@ static int parse_argv(int argc, char *argv[]) {
ARG_NETWORK_VETH,
ARG_NETWORK_BRIDGE,
ARG_PERSONALITY,
ARG_VOLATILE,
};
static const struct option options[] = {
@@ -267,6 +276,7 @@ static int parse_argv(int argc, char *argv[]) {
{ "network-bridge", required_argument, NULL, ARG_NETWORK_BRIDGE },
{ "personality", required_argument, NULL, ARG_PERSONALITY },
{ "image", required_argument, NULL, 'i' },
{ "volatile", optional_argument, NULL, ARG_VOLATILE },
{}
};
@@ -559,6 +569,25 @@ static int parse_argv(int argc, char *argv[]) {
break;
case ARG_VOLATILE:
if (!optarg)
arg_volatile = VOLATILE_YES;
else {
r = parse_boolean(optarg);
if (r < 0) {
if (streq(optarg, "state"))
arg_volatile = VOLATILE_STATE;
else {
log_error("Failed to parse --volatile= argument: %s", optarg);
return r;
}
} else
arg_volatile = r ? VOLATILE_YES : VOLATILE_NO;
}
break;
case '?':
return -EINVAL;
@@ -585,6 +614,11 @@ static int parse_argv(int argc, char *argv[]) {
return -EINVAL;
}
if (arg_volatile != VOLATILE_NO && arg_read_only) {
log_error("Cannot combine --read-only with --volatile. Note that --volatile already implies a read-only base hierarchy.");
return -EINVAL;
}
arg_retain = (arg_retain | plus | (arg_private_network ? 1ULL << CAP_NET_ADMIN : 0)) & ~minus;
return 1;
@@ -712,7 +746,7 @@ static int mount_binds(const char *dest, char **l, bool ro) {
}
/* Create the mount point, but be conservative -- refuse to create block
* and char devices. */
* and char devices. */
if (S_ISDIR(source_st.st_mode))
mkdir_label(where, 0755);
else if (S_ISFIFO(source_st.st_mode))
@@ -796,7 +830,6 @@ static int setup_timezone(const char *dest) {
if (!y)
y = path_startswith(q, "/usr/share/zoneinfo/");
/* Already pointing to the right place? Then do nothing .. */
if (y && streq(y, z))
return 0;
@@ -815,7 +848,9 @@ static int setup_timezone(const char *dest) {
if (!what)
return log_oom();
mkdir_parents(where, 0755);
unlink(where);
if (symlink(what, where) < 0) {
log_error("Failed to correct timezone of container: %m");
return 0;
@@ -839,11 +874,105 @@ static int setup_resolv_conf(const char *dest) {
/* We don't really care for the results of this really. If it
* fails, it fails, but meh... */
mkdir_parents(where, 0755);
copy_file("/etc/resolv.conf", where, O_TRUNC|O_NOFOLLOW, 0644);
return 0;
}
static int setup_volatile_state(const char *directory) {
const char *p;
int r;
assert(directory);
if (arg_volatile != VOLATILE_STATE)
return 0;
/* --volatile=state means we simply overmount /var
with a tmpfs, and the rest read-only. */
r = bind_remount_recursive(directory, true);
if (r < 0) {
log_error("Failed to remount %s read-only: %s", directory, strerror(-r));
return r;
}
p = strappenda(directory, "/var");
mkdir(p, 0755);
if (mount("tmpfs", p, "tmpfs", MS_STRICTATIME, "mode=755") < 0) {
log_error("Failed to mount tmpfs to /var: %m");
return -errno;
}
return 0;
}
static int setup_volatile(const char *directory) {
bool tmpfs_mounted = false, bind_mounted = false;
char template[] = "/tmp/nspawn-volatile-XXXXXX";
const char *f, *t;
int r;
assert(directory);
if (arg_volatile != VOLATILE_YES)
return 0;
/* --volatile=yes means we mount a tmpfs to the root dir, and
the original /usr to use inside it, and that read-only. */
if (!mkdtemp(template)) {
log_error("Failed to create temporary directory: %m");
return -errno;
}
if (mount("tmpfs", template, "tmpfs", MS_STRICTATIME, "mode=755") < 0) {
log_error("Failed to mount tmpfs for root directory: %m");
r = -errno;
goto fail;
}
tmpfs_mounted = true;
f = strappenda(directory, "/usr");
t = strappenda(template, "/usr");
mkdir(t, 0755);
if (mount(f, t, "bind", MS_BIND|MS_REC, NULL) < 0) {
log_error("Failed to create /usr bind mount: %m");
r = -errno;
goto fail;
}
bind_mounted = true;
r = bind_remount_recursive(t, true);
if (r < 0) {
log_error("Failed to remount %s read-only: %s", t, strerror(-r));
goto fail;
}
if (mount(template, directory, NULL, MS_MOVE, NULL) < 0) {
log_error("Failed to move root mount: %m");
r = -errno;
goto fail;
}
rmdir(template);
return 0;
fail:
if (bind_mounted)
umount(t);
if (tmpfs_mounted)
umount(template);
rmdir(template);
return r;
}
static char* id128_format_as_uuid(sd_id128_t id, char s[37]) {
snprintf(s, 37,
@@ -2868,7 +2997,11 @@ int main(int argc, char *argv[]) {
goto finish;
}
r = dissect_image(image_fd, &root_device, &root_device_rw, &home_device, &home_device_rw, &srv_device, &srv_device_rw, &secondary);
r = dissect_image(image_fd,
&root_device, &root_device_rw,
&home_device, &home_device_rw,
&srv_device, &srv_device_rw,
&secondary);
if (r < 0)
goto finish;
}
@@ -3042,18 +3175,23 @@ int main(int argc, char *argv[]) {
srv_device, srv_device_rw) < 0)
goto child_fail;
r = base_filesystem_create(arg_directory);
if (r < 0) {
log_error("Failed to create the base filesystem: %s", strerror(-r));
goto child_fail;
}
/* Turn directory into bind mount */
if (mount(arg_directory, arg_directory, "bind", MS_BIND|MS_REC, NULL) < 0) {
log_error("Failed to make bind mount: %m");
goto child_fail;
}
r = setup_volatile(arg_directory);
if (r < 0)
goto child_fail;
if (setup_volatile_state(arg_directory) < 0)
goto child_fail;
r = base_filesystem_create(arg_directory);
if (r < 0)
goto child_fail;
if (arg_read_only) {
k = bind_remount_recursive(arg_directory, true);
if (k < 0) {