feat: check for create_hostname_file key before writing /etc/hostname

cloudinit/config/cc_set_hostname.py

@@ -96,6 +96,13 @@ def handle(name: str, cfg: Config, cloud: Cloud, args: list) -> None:
     if hostname_fqdn is not None:
         cloud.distro.set_option("prefer_fqdn_over_hostname", hostname_fqdn)
 
+    # Set create_hostname_file in distro
+    create_hostname_file = util.get_cfg_option_bool(
+        cfg, "create_hostname_file", None
+    )
+    if create_hostname_file is not None:
+        cloud.distro.set_option("create_hostname_file", create_hostname_file)
+
     (hostname, fqdn, is_default) = util.get_hostname_fqdn(cfg, cloud)
     # Check for previous successful invocation of set_hostname
 

cloudinit/config/cc_update_hostname.py

@@ -99,6 +99,13 @@ def handle(name: str, cfg: Config, cloud: Cloud, args: list) -> None:
     if hostname_fqdn is not None:
         cloud.distro.set_option("prefer_fqdn_over_hostname", hostname_fqdn)
 
+    # Set create_hostname_file in distro
+    create_hostname_file = util.get_cfg_option_bool(
+        cfg, "create_hostname_file", None
+    )
+    if create_hostname_file is not None:
+        cloud.distro.set_option("create_hostname_file", create_hostname_file)
+
     (hostname, fqdn, is_default) = util.get_hostname_fqdn(cfg, cloud)
     if is_default and hostname == "localhost":
         # https://github.com/systemd/systemd/commit/d39079fcaa05e23540d2b1f0270fa31c22a7e9f1

cloudinit/config/schemas/schema-cloud-config-v1.json

@@ -2576,7 +2576,12 @@
         "prefer_fqdn_over_hostname": {
           "type": "boolean",
           "description": "If true, the fqdn will be used if it is set. If false, the hostname will be used. If unset, the result is distro-dependent"
-        }
+        },
+	"create_hostname_file": {
+	   "type": "boolean",
+	   "default": false,
+	   "description": "If false, the hostname file (e.g. /etc/hostname) will not be created if it does not exist. If true, the hostname will always be created."
+	}
       }
     },
     "cc_set_passwords": {
@@ -3064,6 +3069,11 @@
           "type": "boolean",
           "default": null,
           "description": "By default, it is distro-dependent whether cloud-init uses the short hostname or fully qualified domain name when both ``local-hostname` and ``fqdn`` are both present in instance metadata. When set ``true``, use fully qualified domain name if present as hostname instead of short hostname. When set ``false``, use ``hostname`` config value if present, otherwise fallback to ``fqdn``."
+        },
+	"create_hostname_file": {
+	   "type": "boolean",
+	   "default": false,
+	   "description": "If false, the hostname file (e.g. /etc/hostname) will not be created if it does not exist. If true, the hostname will always be created."
         }
       }
     },

cloudinit/distros/alpine.py

@@ -81,7 +81,13 @@ def _write_hostname(self, hostname, filename):
             # so lets see if we can read it first.
             conf = self._read_hostname_conf(filename)
         except IOError:
-            pass
+            create_hostname_file = util.get_cfg_option_bool(
+                self._cfg, "create_hostname_file", True
+            )
+            if create_hostname_file:
+                pass
+            else:
+                return
         if not conf:
             conf = HostnameConf("")
         conf.set_hostname(hostname)

cloudinit/distros/arch.py

@@ -119,7 +119,13 @@ def _write_hostname(self, hostname, filename):
             # so lets see if we can read it first.
             conf = self._read_hostname_conf(filename)
         except IOError:
-            pass
+            create_hostname_file = util.get_cfg_option_bool(
+                self._cfg, "create_hostname_file", True
+            )
+            if create_hostname_file:
+                pass
+            else:
+                return
         if not conf:
             conf = HostnameConf("")
         conf.set_hostname(hostname)

cloudinit/distros/debian.py

@@ -148,7 +148,13 @@ def _write_hostname(self, hostname, filename):
             # so lets see if we can read it first.
             conf = self._read_hostname_conf(filename)
         except IOError:
-            pass
+            create_hostname_file = util.get_cfg_option_bool(
+                self._cfg, "create_hostname_file", True
+            )
+            if create_hostname_file:
+                pass
+            else:
+                return
         if not conf:
             conf = HostnameConf("")
         conf.set_hostname(hostname)

cloudinit/distros/gentoo.py

@@ -183,7 +183,13 @@ def _write_hostname(self, hostname, filename):
             # so lets see if we can read it first.
             conf = self._read_hostname_conf(filename)
         except IOError:
-            pass
+            create_hostname_file = util.get_cfg_option_bool(
+                self._cfg, "create_hostname_file", True
+            )
+            if create_hostname_file:
+                pass
+            else:
+                return
         if not conf:
             conf = HostnameConf("")
 

cloudinit/distros/opensuse.py

@@ -221,18 +221,34 @@ def _set_update_method(self):
                 self.update_method = "zypper"
 
     def _write_hostname(self, hostname, filename):
+        create_hostname_file = util.get_cfg_option_bool(
+            self._cfg, "create_hostname_file"
+        )
         if self.uses_systemd() and filename.endswith("/previous-hostname"):
             util.write_file(filename, hostname)
         elif self.uses_systemd():
-            subp.subp(["hostnamectl", "set-hostname", str(hostname)])
+            if not create_hostname_file:
+                subp.subp(["hostnamectl", "set-hostname", str(hostname)])
+            else:
+                subp.subp(
+                    [
+                        "hostnamectl",
+                        "set-hostname",
+                        "--transient",
+                        str(hostname),
+                    ]
+                )
         else:
             conf = None
             try:
                 # Try to update the previous one
                 # so lets see if we can read it first.
                 conf = self._read_hostname_conf(filename)
             except IOError:
-                pass
+                if not create_hostname_file:
+                    pass
+                else:
+                    return
             if not conf:
                 conf = HostnameConf("")
             conf.set_hostname(hostname)

cloudinit/distros/photon.py

@@ -93,9 +93,23 @@ def _write_hostname(self, hostname, filename):
         if filename and filename.endswith("/previous-hostname"):
             util.write_file(filename, hostname)
         else:
-            ret, _out, err = self.exec_cmd(
-                ["hostnamectl", "set-hostname", str(hostname)]
+            ret = None
+            create_hostname_file = util.get_cfg_option_bool(
+                self._cfg, "create_hostname_file", True
             )
+            if create_hostname_file:
+                ret, _out, err = self.exec_cmd(
+                    ["hostnamectl", "set-hostname", str(hostname)]
+                )
+            else:
+                ret, _out, err = self.exec_cmd(
+                    [
+                        "hostnamectl",
+                        "set-hostname",
+                        "--transient",
+                        str(hostname),
+                    ]
+                )
             if ret:
                 LOG.warning(
                     (

cloudinit/distros/rhel.py

@@ -109,7 +109,20 @@ def _write_hostname(self, hostname, filename):
             conf.set_hostname(hostname)
             util.write_file(filename, str(conf), 0o644)
         elif self.uses_systemd():
-            subp.subp(["hostnamectl", "set-hostname", str(hostname)])
+            create_hostname_file = util.get_cfg_option_bool(
+                self._cfg, "create_hostname_file", True
+            )
+            if create_hostname_file:
+                subp.subp(["hostnamectl", "set-hostname", str(hostname)])
+            else:
+                subp.subp(
+                    [
+                        "hostnamectl",
+                        "set-hostname",
+                        "--transient",
+                        str(hostname),
+                    ]
+                )
         else:
             host_cfg = {
                 "HOSTNAME": hostname,

tests/unittests/config/test_cc_set_hostname.py

@@ -259,5 +259,95 @@ def test_ignore_empty_previous_artifact_file(self):
         contents = util.load_file("/etc/hostname")
         self.assertEqual("blah", contents.strip())
 
+    def test_create_hostname_file_false(self):
+        cfg = {
+            "hostname": "foo",
+            "fqdn": "foo.blah.yahoo.com",
+            "create_hostname_file": False,
+        }
+        distro = self._fetch_distro("debian")
+        paths = helpers.Paths({"cloud_dir": self.tmp})
+        ds = None
+        cc = cloud.Cloud(ds, paths, {}, distro, None)
+        self.patchUtils(self.tmp)
+        cc_set_hostname.handle("cc_set_hostname", cfg, cc, [])
+        with self.assertRaises(FileNotFoundError):
+            util.load_file("/etc/hostname")
+
+    def test_create_hostname_file_false_arch(self):
+        cfg = {
+            "hostname": "foo",
+            "fqdn": "foo.blah.yahoo.com",
+            "create_hostname_file": False,
+        }
+        distro = self._fetch_distro("arch")
+        paths = helpers.Paths({"cloud_dir": self.tmp})
+        ds = None
+        cc = cloud.Cloud(ds, paths, {}, distro, None)
+        self.patchUtils(self.tmp)
+        cc_set_hostname.handle("cc_set_hostname", cfg, cc, [])
+        with self.assertRaises(FileNotFoundError):
+            util.load_file("/etc/hostname")
+
+    def test_create_hostname_file_false_alpine(self):
+        cfg = {
+            "hostname": "foo",
+            "fqdn": "foo.blah.yahoo.com",
+            "create_hostname_file": False,
+        }
+        distro = self._fetch_distro("alpine")
+        paths = helpers.Paths({"cloud_dir": self.tmp})
+        ds = None
+        cc = cloud.Cloud(ds, paths, {}, distro, None)
+        self.patchUtils(self.tmp)
+        cc_set_hostname.handle("cc_set_hostname", cfg, cc, [])
+        with self.assertRaises(FileNotFoundError):
+            util.load_file("/etc/hostname")
+
+    def test_create_hostname_file_false_gentoo(self):
+        cfg = {
+            "hostname": "foo",
+            "fqdn": "foo.blah.yahoo.com",
+            "create_hostname_file": False,
+        }
+        distro = self._fetch_distro("gentoo")
+        paths = helpers.Paths({"cloud_dir": self.tmp})
+        ds = None
+        cc = cloud.Cloud(ds, paths, {}, distro, None)
+        self.patchUtils(self.tmp)
+        cc_set_hostname.handle("cc_set_hostname", cfg, cc, [])
+        with self.assertRaises(FileNotFoundError):
+            util.load_file("/etc/hostname")
+
+    def test_create_hostname_file_false_photon(self):
+        cfg = {
+            "hostname": "foo",
+            "fqdn": "foo.blah.yahoo.com",
+            "create_hostname_file": False,
+        }
+        distro = self._fetch_distro("photon")
+        paths = helpers.Paths({"cloud_dir": self.tmp})
+        ds = None
+        cc = cloud.Cloud(ds, paths, {}, distro, None)
+        self.patchUtils(self.tmp)
+        cc_set_hostname.handle("cc_set_hostname", cfg, cc, [])
+        with self.assertRaises(FileNotFoundError):
+            util.load_file("/etc/hostname")
+
+    def test_create_hostname_file_false_rhel(self):
+        cfg = {
+            "hostname": "foo",
+            "fqdn": "foo.blah.yahoo.com",
+            "create_hostname_file": False,
+        }
+        distro = self._fetch_distro("rhel")
+        paths = helpers.Paths({"cloud_dir": self.tmp})
+        ds = None
+        cc = cloud.Cloud(ds, paths, {}, distro, None)
+        self.patchUtils(self.tmp)
+        cc_set_hostname.handle("cc_set_hostname", cfg, cc, [])
+        with self.assertRaises(FileNotFoundError):
+            util.load_file("/etc/hostname")
+
 
 # vi: ts=4 expandtab

tools/.github-cla-signers

@@ -25,6 +25,7 @@ bmhughes
 brianphaley
 CalvoM
 candlerb
+catmsred
 cawamata
 cclauss
 chifac08