net: recognize iscsi root cases without ip= on kernel command line.

When 'ip=' or 'ip6=' is found on the kernel command line,
cloud-init will consider read network config from /run/net-*.conf files.

There are some iscsi-root scenarios where initramfs configures networking
but the ip= parameter is not present. 2 such cases are:
 a.) static config in /etc/iscsi/iscsi.initramfs (copied into the
initramfs)
 b.) iBft

This changes cloud-init to consider initramfs provided networking
information if:
 * there are /run/net-* files and
 * (ip= or ip6 is on the command line) or open-iscsi.interface file
exists.

LP: #1752391

2 files changed, 29 insertions, 4 deletions

diff --git a/cloudinit/net/cmdline.py b/cloudinit/net/cmdline.py
index 7b2cc9db..9e9fe0fe 100755
--- a/cloudinit/net/cmdline.py
+++ b/cloudinit/net/cmdline.py
@@ -9,12 +9,15 @@ import base64
 import glob
 import gzip
 import io
+import os
 
 from . import get_devicelist
 from . import read_sys_net_safe
 
 from cloudinit import util
 
+_OPEN_ISCSI_INTERFACE_FILE = "/run/initramfs/open-iscsi.interface"
+
 
 def _klibc_to_config_entry(content, mac_addrs=None):
     """Convert a klibc written shell content file to a 'config' entry
@@ -103,9 +106,13 @@ def _klibc_to_config_entry(content, mac_addrs=None):
     return name, iface
 
 
+def _get_klibc_net_cfg_files():
+    return glob.glob('/run/net-*.conf') + glob.glob('/run/net6-*.conf')
+
+
 def config_from_klibc_net_cfg(files=None, mac_addrs=None):
     if files is None:
-        files = glob.glob('/run/net-*.conf') + glob.glob('/run/net6-*.conf')
+        files = _get_klibc_net_cfg_files()
 
     entries = []
     names = {}
@@ -160,10 +167,23 @@ def _b64dgz(b64str, gzipped="try"):
     return _decomp_gzip(blob, strict=gzipped != "try")
 
 
+def _is_initramfs_netconfig(files, cmdline):
+    if files:
+        if 'ip=' in cmdline or 'ip6=' in cmdline:
+            return True
+        if os.path.exists(_OPEN_ISCSI_INTERFACE_FILE):
+            # iBft can configure networking without ip=
+            return True
+    return False
+
+
 def read_kernel_cmdline_config(files=None, mac_addrs=None, cmdline=None):
     if cmdline is None:
         cmdline = util.get_cmdline()
 
+    if files is None:
+        files = _get_klibc_net_cfg_files()
+
     if 'network-config=' in cmdline:
         data64 = None
         for tok in cmdline.split():
@@ -172,7 +192,7 @@ def read_kernel_cmdline_config(files=None, mac_addrs=None, cmdline=None):
         if data64:
             return util.load_yaml(_b64dgz(data64))
 
-    if 'ip=' not in cmdline and 'ip6=' not in cmdline:
+    if not _is_initramfs_netconfig(files, cmdline):
         return None
 
     if mac_addrs is None:
diff --git a/cloudinit/tests/helpers.py b/cloudinit/tests/helpers.py
index a2e10536..999b1d7c 100644
--- a/cloudinit/tests/helpers.py
+++ b/cloudinit/tests/helpers.py
@@ -283,10 +283,15 @@ class FilesystemMockingTestCase(ResourceUsingTestCase):
     def patchOS(self, new_root):
         patch_funcs = {
             os.path: [('isfile', 1), ('exists', 1),
-                      ('islink', 1), ('isdir', 1)],
+                      ('islink', 1), ('isdir', 1), ('lexists', 1)],
             os: [('listdir', 1), ('mkdir', 1),
-                 ('lstat', 1), ('symlink', 2)],
+                 ('lstat', 1), ('symlink', 2)]
         }
+
+        if hasattr(os, 'scandir'):
+            # py27 does not have scandir
+            patch_funcs[os].append(('scandir', 1))
+
         for (mod, funcs) in patch_funcs.items():
             for f, nargs in funcs:
                 func = getattr(mod, f)