Merge pull request #21252 from poettering/homed-record-dir-env-var

homed: add env var to override dir where we fine stored user records

docs/ENVIRONMENT.md

@@ -401,3 +401,35 @@ and `homectl`:
   current and a future password are required, for example if the password is to
   be changed. In that case `$PASSWORD` shall carry the current (i.e. old)
   password and `$NEWPASSWORD` the new.
+
+`systemd-homed`:
+
+* `$SYSTEMD_HOME_ROOT` – defines an absolute path where to look for home
+  directories/images. When unspecified defaults to `/home/`. This is useful for
+  debugging purposes in order to run a secondary `systemd-homed` instance that
+  operates on a different directory where home directories/images are placed.
+
+* `$SYSTEMD_HOME_RECORD_DIR` – defines an absolute path where to look for
+  fixated home records kept on the host. When unspecified defaults to
+  `/var/lib/systemd/home/`. Similar to `$SYSTEMD_HOME_ROOT` this is useful for
+  debugging purposes, in order to run a secondary `systemd-homed` instance that
+  operates on a record database entirely separate from the host's.
+
+* `$SYSTEMD_HOME_DEBUG_SUFFIX` – takes a short string that is suffixed to
+  `systemd-homed`'s D-Bus and Varlink service names/sockets. This is also
+  understood by `homectl`. This too is useful for running an additiona copy of
+  `systemd-homed` that doesn't interfere with the host's main one.
+
+* `$SYSTEMD_HOMEWORK_PATH` – configures the path to the `systemd-homework`
+  binary to invoke. If not specified defaults to
+  `/usr/lib/systemd/systemd-homework`.
+
+  Combining these four environment variables is pretty useful when
+  debugging/developing `systemd-homed`:
+```sh
+SYSTEMD_HOME_DEBUG_SUFFIX=foo \
+      SYSTEMD_HOMEWORK_PATH=/home/lennart/projects/systemd/build/systemd-homework \
+      SYSTEMD_HOME_ROOT=/home.foo/ \
+      SYSTEMD_HOME_RECORD_DIR=/var/lib/systemd/home.foo/ \
+      /home/lennart/projects/systemd/build/systemd-homed
+```

src/home/home-util.c

@@ -133,3 +133,7 @@ int bus_message_append_secret(sd_bus_message *m, UserRecord *secret) {
 
         return sd_bus_message_append(m, "s", formatted);
 }
+
+const char *home_record_dir(void) {
+        return secure_getenv("SYSTEMD_HOME_RECORD_DIR") ?: "/var/lib/systemd/home/";
+}

src/home/home-util.h

@@ -25,3 +25,5 @@ int bus_message_append_secret(sd_bus_message *m, UserRecord *secret);
 /* Many of our operations might be slow due to crypto, fsck, recursive chown() and so on. For these
  * operations permit a *very* long timeout */
 #define HOME_SLOW_BUS_CALL_TIMEOUT_USEC (2*USEC_PER_MINUTE)
+
+const char *home_record_dir(void);

src/home/homed-home.c

@@ -300,9 +300,9 @@ int home_save_record(Home *h) {
                 return r;
 
         (void) mkdir("/var/lib/systemd/", 0755);
-        (void) mkdir("/var/lib/systemd/home/", 0700);
+        (void) mkdir(home_record_dir(), 0700);
 
-        fn = strjoina("/var/lib/systemd/home/", h->user_name, ".identity");
+        fn = strjoina(home_record_dir(), "/", h->user_name, ".identity");
 
         r = write_string_file(fn, text, WRITE_STRING_FILE_ATOMIC|WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_MODE_0600|WRITE_STRING_FILE_SYNC);
         if (r < 0)
@@ -316,7 +316,7 @@ int home_unlink_record(Home *h) {
 
         assert(h);
 
-        fn = strjoina("/var/lib/systemd/home/", h->user_name, ".identity");
+        fn = strjoina(home_record_dir(), "/", h->user_name, ".identity");
         if (unlink(fn) < 0 && errno != ENOENT)
                 return -errno;
 

src/home/homed-manager.c

@@ -436,7 +436,7 @@ unlink_this_file:
         if (unlinkat(dir_fd, fname, 0) < 0)
                 return log_error_errno(errno, "Failed to remove empty user record file %s: %m", fname);
 
-        log_notice("Discovered empty user record file /var/lib/systemd/home/%s, removed automatically.", fname);
+        log_notice("Discovered empty user record file %s/%s, removed automatically.", home_record_dir(), fname);
         return 0;
 }
 
@@ -446,10 +446,10 @@ static int manager_enumerate_records(Manager *m) {
 
         assert(m);
 
-        d = opendir("/var/lib/systemd/home/");
+        d = opendir(home_record_dir());
         if (!d)
                 return log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_ERR, errno,
-                                      "Failed to open /var/lib/systemd/home/: %m");
+                                      "Failed to open %s: %m", home_record_dir());
 
         FOREACH_DIRENT(de, d, return log_error_errno(errno, "Failed to read record directory: %m")) {
                 _cleanup_free_ char *n = NULL;