transaction: downgrade warnings about wanted unit which are not found

If a unit was pulled by a Wants= dependency but its unit file was not
present then we logged this as an error.

However Wants= might be used to configure a soft/optional dependency
on another unit, ie. start an optional service only if it's installed
otherwise simply skip it. In this case emitting an error doesn't look
appropriate.

But it's still an error if the optional dependency exists but its
activation fails for any reasons.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/core/transaction.c b/src/core/transaction.c
index 2f163190e9..bc85cef266 100644
--- a/src/core/transaction.c
+++ b/src/core/transaction.c
@@ -949,9 +949,10 @@ int transaction_add_job_and_dependencies(
                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_WANTS], i) {
                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, false, false, false, ignore_order, e);
                                 if (r < 0) {
+                                        /* unit masked and unit not found are not considered as errors. */
                                         log_unit_full(dep,
-                                                      r == -EBADR /* unit masked */ ? LOG_DEBUG : LOG_WARNING, r,
-                                                      "Cannot add dependency job, ignoring: %s",
+                                                      r == -EBADR || r == -ENOENT ? LOG_DEBUG : LOG_WARNING,
+                                                      r, "Cannot add dependency job, ignoring: %s",
                                                       bus_error_message(e, r));
                                         sd_bus_error_free(e);
                                 }