nspawn: allow spawning ephemeral nspawn containers based on the root file system...

[elogind.git] / src / nspawn / nspawn.c

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 1bfc99d5fcaa37129fcd6e85304caa54e8fa959c..651a45126b8585b7e0037e76a53c553318b2fdf5 100644 (file)
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -477,15 +477,19 @@ static int parse_argv(int argc, char *argv[]) {
                         break;
 
                 case ARG_LINK_JOURNAL:
-                        if (streq(optarg, "auto"))
+                        if (streq(optarg, "auto")) {
                                 arg_link_journal = LINK_AUTO;
-                        else if (streq(optarg, "no"))
+                                arg_link_journal_try = false;
+                        } else if (streq(optarg, "no")) {
                                 arg_link_journal = LINK_NO;
-                        else if (streq(optarg, "guest"))
+                                arg_link_journal_try = false;
+                        } else if (streq(optarg, "guest")) {
                                 arg_link_journal = LINK_GUEST;
-                        else if (streq(optarg, "host"))
+                                arg_link_journal_try = false;
+                        } else if (streq(optarg, "host")) {
                                 arg_link_journal = LINK_HOST;
-                        else if (streq(optarg, "try-guest")) {
+                                arg_link_journal_try = false;
+                        } else if (streq(optarg, "try-guest")) {
                                 arg_link_journal = LINK_GUEST;
                                 arg_link_journal_try = true;
                         } else if (streq(optarg, "try-host")) {
@@ -683,6 +687,11 @@ static int parse_argv(int argc, char *argv[]) {
                 return -EINVAL;
         }
 
+        if (arg_ephemeral && !IN_SET(arg_link_journal, LINK_NO, LINK_AUTO)) {
+                log_error("--ephemeral and --link-journal= may not be combined.");
+                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;
@@ -1313,6 +1322,10 @@ static int setup_journal(const char *directory) {
         char *id;
         int r;
 
+        /* Don't link journals in ephemeral mode */
+        if (arg_ephemeral)
+                return 0;
+
         p = strappend(directory, "/etc/machine-id");
         if (!p)
                 return log_oom();
@@ -1341,8 +1354,7 @@ static int setup_journal(const char *directory) {
                          "Host and machine ids are equal (%s): refusing to link journals", id);
                 if (arg_link_journal == LINK_AUTO)
                         return 0;
-                return
-                        -EEXIST;
+                return -EEXIST;
         }
 
         if (arg_link_journal == LINK_NO)
@@ -2930,8 +2942,8 @@ int main(int argc, char *argv[]) {
         if (arg_directory) {
                 assert(!arg_image);
 
-                if (path_equal(arg_directory, "/")) {
-                        log_error("Spawning container on root directory not supported.");
+                if (path_equal(arg_directory, "/") && !arg_ephemeral) {
+                        log_error("Spawning container on root directory is not supported. Consider using --ephemeral.");
                         r = -EINVAL;
                         goto finish;
                 }
@@ -2952,7 +2964,21 @@ int main(int argc, char *argv[]) {
                 } else if (arg_ephemeral) {
                         char *np;
 
-                        r = tempfn_random(arg_directory, &np);
+                        /* If the specified path is a mount point we
+                         * generate the new snapshot immediately
+                         * inside it under a random name. However if
+                         * the specified is not a mount point we
+                         * create the new snapshot in the parent
+                         * directory, just next to it. */
+                        r = path_is_mount_point(arg_directory, false);
+                        if (r < 0) {
+                                log_error_errno(r, "Failed to determine whether directory %s is mount point: %m", arg_directory);
+                                goto finish;
+                        }
+                        if (r > 0)
+                                r = tempfn_random_child(arg_directory, &np);
+                        else
+                                r = tempfn_random(arg_directory, &np);
                         if (r < 0) {
                                 log_error_errno(r, "Failed to generate name for snapshot: %m");
                                 goto finish;