dmi: Add support for OpenBSD

OpenBSD has the most important DMI data in sysctl's hw hierarchy.
Extend dmi to read those, instead of falling back to dmidecode, since
that requires setting kern.allowkmem=1

cloudinit/dmi.py

@@ -6,18 +6,20 @@
 from typing import Optional
 
 from cloudinit import subp
-from cloudinit.util import is_container, is_FreeBSD
+from cloudinit.util import is_container, is_FreeBSD, is_DragonFlyBSD, is_OpenBSD
 
 LOG = logging.getLogger(__name__)
 
 # Path for DMI Data
 DMI_SYS_PATH = "/sys/class/dmi/id"
 
-KernelNames = namedtuple("KernelNames", ["linux", "freebsd"])
-KernelNames.__new__.__defaults__ = (None, None)
+KernelNames = namedtuple("KernelNames", ["linux", "freebsd", "openbsd"])
+KernelNames.__new__.__defaults__ = (None, None, None)
 
 # FreeBSD's kenv(1) and Linux /sys/class/dmi/id/* both use different names from
 # dmidecode. The values are the same, and ultimately what we're interested in.
+# Likewise, OpenBSD has pretty much all the things we need (use) in sysctl(8)'s
+# hw hierarchy.
 # These tools offer a "cheaper" way to access those values over dmidecode.
 # This is our canonical translation table. If we add more tools on other
 # platforms to find dmidecode's values, their keys need to be put in here.
@@ -40,22 +42,22 @@
         "chassis_asset_tag", "smbios.chassis.tag"
     ),
     "chassis-manufacturer": KernelNames(
-        "chassis_vendor", "smbios.chassis.maker"
+        "chassis_vendor", "smbios.chassis.maker", "hw.vendor"
     ),
     "chassis-serial-number": KernelNames(
-        "chassis_serial", "smbios.chassis.serial"
+        "chassis_serial", "smbios.chassis.serial", "hw.uuid"
     ),
     "chassis-version": KernelNames(
         "chassis_version", "smbios.chassis.version"
     ),
-    "system-manufacturer": KernelNames("sys_vendor", "smbios.system.maker"),
+    "system-manufacturer": KernelNames("sys_vendor", "smbios.system.maker", "hw.vendor"),
     "system-product-name": KernelNames(
-        "product_name", "smbios.system.product"
+        "product_name", "smbios.system.product", "hw.product"
     ),
     "system-serial-number": KernelNames(
-        "product_serial", "smbios.system.serial"
+        "product_serial", "smbios.system.serial", "hw.uuid"
     ),
-    "system-uuid": KernelNames("product_uuid", "smbios.system.uuid"),
+    "system-uuid": KernelNames("product_uuid", "smbios.system.uuid", "hw.uuid"),
     "system-version": KernelNames("product_version", "smbios.system.version"),
 }
 
@@ -119,6 +121,27 @@ def _read_kenv(key: str) -> Optional[str]:
 
     return None
 
+def _read_sysctl(key: str) -> Optional[str]:
+    """
+    Reads dmi data from OpenBSD's sysctl(8)
+    """
+    kmap = DMIDECODE_TO_KERNEL.get(key)
+    if kmap is None or kmap.openbsd is None:
+        return None
+
+    LOG.debug("querying dmi data %s", kmap.openbsd)
+
+    try:
+        cmd = ["sysctl", "-qn", kmap.openbsd]
+        (result, _err) = subp.subp(cmd)
+        result = result.strip()
+        LOG.debug("sysctl returned '%s' for '%s'", result, kmap.openbsd)
+        return result
+    except subp.ProcessExecutionError as e:
+        LOG.debug("failed sysctl cmd: %s\n%s", cmd, e)
+
+    return None
+
 
 def _call_dmidecode(key: str, dmidecode_path: str) -> Optional[str]:
     """
@@ -159,9 +182,12 @@ def read_dmi_data(key: str) -> Optional[str]:
     if is_container():
         return None
 
-    if is_FreeBSD():
+    if is_FreeBSD() or is_DragonFlyBSD():
         return _read_kenv(key)
 
+    if is_OpenBSD():
+        return _read_sysctl(key)
+
     syspath_value = _read_dmi_syspath(key)
     if syspath_value is not None:
         return syspath_value