nspawn: deprecate --share-system support

This removes the --share-system switch: from the documentation, the --help text
as well as the command line parsing. It's an ugly option, given that it kinda
contradicts the whole concept of PID namespaces that nspawn implements. Since
it's barely ever used, let's just deprecate it and remove it from the options.

It might be useful as a debugging option, hence the functionality is kept
around for now, exposed via an undocumented $SYSTEMD_NSPAWN_SHARE_SYSTEM
environment variable.

1 files changed, 7 insertions, 3 deletions

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 05e1fc1ab7..b7c2fe9e55 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -269,7 +269,6 @@ static void help(void) {
                "     --overlay-ro=PATH[:PATH...]:PATH\n"
                "                            Similar, but creates a read-only overlay mount\n"
                "  -E --setenv=NAME=VALUE    Pass an environment variable to PID 1\n"
-               "     --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"
@@ -405,7 +404,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "selinux-context",       required_argument, NULL, 'Z'                   },
                 { "selinux-apifs-context", required_argument, NULL, 'L'                   },
                 { "quiet",                 no_argument,       NULL, 'q'                   },
-                { "share-system",          no_argument,       NULL, ARG_SHARE_SYSTEM      },
+                { "share-system",          no_argument,       NULL, ARG_SHARE_SYSTEM      }, /* not documented */
                 { "register",              required_argument, NULL, ARG_REGISTER          },
                 { "keep-unit",             no_argument,       NULL, ARG_KEEP_UNIT         },
                 { "network-interface",     required_argument, NULL, ARG_NETWORK_INTERFACE },
@@ -814,6 +813,8 @@ static int parse_argv(int argc, char *argv[]) {
                         break;
 
                 case ARG_SHARE_SYSTEM:
+                        /* We don't officially support this anymore, except for compat reasons. People should use the
+                         * $SYSTEMD_NSPAWN_SHARE_SYSTEM environment variable instead. */
                         arg_share_system = true;
                         break;
 
@@ -1018,6 +1019,9 @@ static int parse_argv(int argc, char *argv[]) {
                         assert_not_reached("Unhandled option");
                 }
 
+        if (getenv_bool("SYSTEMD_NSPAWN_SHARE_SYSTEM") > 0)
+                arg_share_system = true;
+
         if (arg_share_system)
                 arg_register = false;
 
@@ -1025,7 +1029,7 @@ static int parse_argv(int argc, char *argv[]) {
                 arg_userns_chown = true;
 
         if (arg_start_mode != START_PID1 && arg_share_system) {
-                log_error("--boot and --share-system may not be combined.");
+                log_error("--boot and SYSTEMD_NSPAWN_SHARE_SYSTEM=1 may not be combined.");
                 return -EINVAL;
         }