nspawn: support custom container service name

We were hardcoding "systemd-nspawn" as the value of the $container env
variable and "nspawn" as the service string in machined registration.

This commit allows the user to configure it by setting the
$SYSTEMD_NSPAWN_CONTAINER_SERVICE env variable when calling
systemd-nspawn.

If $SYSTEMD_NSPAWN_CONTAINER_SERVICE is not set, we use the string
"systemd-nspawn" for both, fixing the previous inconsistency.

3 files changed, 18 insertions, 8 deletions

diff --git a/src/nspawn/nspawn-register.c b/src/nspawn/nspawn-register.c
index 7139ad9958..374f958c20 100644
--- a/src/nspawn/nspawn-register.c
+++ b/src/nspawn/nspawn-register.c
@@ -39,7 +39,8 @@ int register_machine(
                 unsigned n_mounts,
                 int kill_signal,
                 char **properties,
-                bool keep_unit) {
+                bool keep_unit,
+                const char *service) {
 
         _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
         _cleanup_bus_flush_close_unref_ sd_bus *bus = NULL;
@@ -61,7 +62,7 @@ int register_machine(
                                 "sayssusai",
                                 machine_name,
                                 SD_BUS_MESSAGE_APPEND_ID128(uuid),
-                                "nspawn",
+                                service,
                                 "container",
                                 (uint32_t) pid,
                                 strempty(directory),
@@ -86,7 +87,7 @@ int register_machine(
                                 "sayssusai",
                                 machine_name,
                                 SD_BUS_MESSAGE_APPEND_ID128(uuid),
-                                "nspawn",
+                                service,
                                 "container",
                                 (uint32_t) pid,
                                 strempty(directory),
diff --git a/src/nspawn/nspawn-register.h b/src/nspawn/nspawn-register.h
index b27841ff59..d3bfd84e5e 100644
--- a/src/nspawn/nspawn-register.h
+++ b/src/nspawn/nspawn-register.h
@@ -27,5 +27,5 @@
 
 #include "nspawn-mount.h"
 
-int register_machine(const char *machine_name, pid_t pid, const char *directory, sd_id128_t uuid, int local_ifindex, const char *slice, CustomMount *mounts, unsigned n_mounts, int kill_signal, char **properties, bool keep_unit);
+int register_machine(const char *machine_name, pid_t pid, const char *directory, sd_id128_t uuid, int local_ifindex, const char *slice, CustomMount *mounts, unsigned n_mounts, int kill_signal, char **properties, bool keep_unit, const char *service);
 int terminate_machine(pid_t pid);
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index ff12ca6498..4c426e6874 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -178,6 +178,7 @@ static bool arg_unified_cgroup_hierarchy = false;
 static SettingsMask arg_settings_mask = 0;
 static int arg_settings_trusted = -1;
 static char **arg_parameters = NULL;
+static const char *arg_container_service_name = "systemd-nspawn";
 
 static void help(void) {
         printf("%s [OPTIONS...] [PATH] [ARGUMENTS...]\n\n"
@@ -387,7 +388,7 @@ static int parse_argv(int argc, char *argv[]) {
         };
 
         int c, r;
-        const char *p;
+        const char *p, *e;
         uint64_t plus = 0, minus = 0;
         bool mask_all_settings = false, mask_no_settings = false;
 
@@ -909,6 +910,10 @@ static int parse_argv(int argc, char *argv[]) {
         if (r < 0)
                 return r;
 
+        e = getenv("SYSTEMD_NSPAWN_CONTAINER_SERVICE");
+        if (e)
+                arg_container_service_name = e;
+
         return 1;
 }
 
@@ -2404,10 +2409,10 @@ static int inner_child(
                 FDSet *fds) {
 
         _cleanup_free_ char *home = NULL;
-        unsigned n_env = 2;
+        unsigned n_env = 1;
         const char *envp[] = {
                 "PATH=" DEFAULT_PATH_SPLIT_USR,
-                "container=systemd-nspawn", /* LXC sets container=lxc, so follow the scheme here */
+                NULL, /* container */
                 NULL, /* TERM */
                 NULL, /* HOME */
                 NULL, /* USER */
@@ -2508,6 +2513,9 @@ static int inner_child(
         if (r < 0)
                 return r;
 
+        /* LXC sets container=lxc, so follow the scheme here */
+        envp[n_env++] = strjoina("container=", arg_container_service_name);
+
         envp[n_env] = strv_find_prefix(environ, "TERM=");
         if (envp[n_env])
                 n_env ++;
@@ -3426,7 +3434,8 @@ int main(int argc, char *argv[]) {
                                         arg_custom_mounts, arg_n_custom_mounts,
                                         arg_kill_signal,
                                         arg_property,
-                                        arg_keep_unit);
+                                        arg_keep_unit,
+                                        arg_container_service_name);
                         if (r < 0)
                                 goto finish;
                 }