ds-identify: check /writable/system-data/ for nocloud seed.

Ubuntu core seeds information to nocloud via a bind-mount of
/writable/system-data/var/lib/cloud over /var/lib/cloud.
When ds-identify runs as a systemd generator that mount is not
guaranteed to have been done.  It is guaranteed at
cloud-init-local.service time, but not generator time.

Images built with 'ubuntu-image --cloud-init=user-data-file'
would have cloud-init disabled.

The fix here is just to consider the seed dir under /writable/system-data.

LP: #1747070

2 files changed, 35 insertions, 0 deletions

diff --git a/tests/unittests/test_ds_identify.py b/tests/unittests/test_ds_identify.py
index 31cc6223..03942de0 100644
--- a/tests/unittests/test_ds_identify.py
+++ b/tests/unittests/test_ds_identify.py
@@ -359,6 +359,14 @@ class TestDsIdentify(CiTestCase):
         """NoCloud is found with iso9660 filesystem on non-cdrom disk."""
         self._test_ds_found('NoCloud')
 
+    def test_nocloud_seed(self):
+        """Nocloud seed directory."""
+        self._test_ds_found('NoCloud-seed')
+
+    def test_nocloud_seed_ubuntu_core_writable(self):
+        """Nocloud seed directory ubuntu core writable"""
+        self._test_ds_found('NoCloud-seed-ubuntu-core')
+
 
 def blkid_out(disks=None):
     """Convert a list of disk dictionaries into blkid content."""
@@ -454,6 +462,22 @@ VALID_CFG = {
             'dev/vdb': 'pretend iso content for cidata\n',
         }
     },
+    'NoCloud-seed': {
+        'ds': 'NoCloud',
+        'files': {
+            os.path.join(P_SEED_DIR, 'nocloud', 'user-data'): 'ud\n',
+            os.path.join(P_SEED_DIR, 'nocloud', 'meta-data'): 'md\n',
+        }
+    },
+    'NoCloud-seed-ubuntu-core': {
+        'ds': 'NoCloud',
+        'files': {
+            os.path.join('writable/system-data', P_SEED_DIR,
+                         'nocloud-net', 'user-data'): 'ud\n',
+            os.path.join('writable/system-data', P_SEED_DIR,
+                         'nocloud-net', 'meta-data'): 'md\n',
+        }
+    },
     'OpenStack': {
         'ds': 'OpenStack',
         'files': {P_PRODUCT_NAME: 'OpenStack Nova\n'},
diff --git a/tools/ds-identify b/tools/ds-identify
index cd268242..5f762438 100755
--- a/tools/ds-identify
+++ b/tools/ds-identify
@@ -470,6 +470,16 @@ check_seed_dir() {
     return 0
 }
 
+check_writable_seed_dir() {
+    # ubuntu core bind-mounts /writable/system-data/var/lib/cloud
+    # over the top of /var/lib/cloud, but the mount might not be done yet.
+    local wdir="/writable/system-data"
+    [ -d "${PATH_ROOT}$wdir" ] || return 1
+    local sdir="${PATH_ROOT}$wdir${PATH_VAR_LIB_CLOUD#${PATH_ROOT}}"
+    local PATH_VAR_LIB_CLOUD="$sdir"
+    check_seed_dir "$@"
+}
+
 probe_floppy() {
     cached "${STATE_FLOPPY_PROBED}" && return "${STATE_FLOPPY_PROBED}"
     local fpath=/dev/floppy
@@ -569,6 +579,7 @@ dscheck_NoCloud() {
     esac
     for d in nocloud nocloud-net; do
         check_seed_dir "$d" meta-data user-data && return ${DS_FOUND}
+        check_writable_seed_dir "$d" meta-data user-data && return ${DS_FOUND}
     done
     if has_fs_with_label "${fslabel}"; then
         return ${DS_FOUND}