installer: seed /etc/locale.conf before package install

dracut's 20i18n module reads /etc/locale.conf when it builds an initrd, and
the initramfs rpm installs a file trigger that runs mkinitrd at the END of the
package transaction started by _install_packages(). m_locale ran at
POST_INSTALL, so the file was written after that trigger had already fired.
dracut therefore aborted i18n setup with

    "i18n_vars not set!  Please set up i18n_vars in  configuration file."

and fell back to embedding every keymap.

Move the write into the PRE_PKGS_INSTALL phase, where it lands before the
transaction. _initialize_system() runs immediately before that phase, so the
file appears at very nearly the same point in the sequence.

localedef cannot move with it. It runs inside the chroot, and at
PRE_PKGS_INSTALL the target holds only an initialised rpm database and the
`filesystem` rpm - glibc, which provides /usr/bin/localedef, is not installed
until _install_packages(). So locale setup is split along the line the phases
already draw:

  m_locale.py     PRE_PKGS_INSTALL  writes /etc/locale.conf
  m_localedef.py  POST_INSTALL      runs localedef

A separate module rather than a two-phase one because install_phase is a
scalar compared with !=, in both photon-os-installer 2.8 and master; making a
single module span two phases would mean changing the dispatcher, and 2.8 does
not even have the MODULES_DISPATCHABLE_PHASES guard that master added. Two
modules need no dispatcher change and behave identically on both.

Signed-off-by: Daniel Casota <dcasota@gmail.com>
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JW73JTCUGRcaNTUEQcAMtf

Author: dcasota

photon_installer/modules/m_locale.py

@@ -7,24 +7,24 @@
 
 import commons
 
-install_phase = commons.POST_INSTALL
+# PRE_PKGS_INSTALL, not POST_INSTALL: dracut's 20i18n module reads
+# /etc/locale.conf when it builds an initrd, and the initramfs rpm installs a
+# file trigger that runs mkinitrd at the END of the package transaction started
+# by _install_packages(). A file written after that transaction is written too
+# late. Without it dracut aborts i18n setup with
+#     "i18n_vars not set!  Please set up i18n_vars in  configuration file."
+# and falls back to embedding every keymap.
+#
+# _initialize_system() runs immediately before this phase, so the file lands at
+# very nearly the same point in the sequence as it would have from there, but
+# in the module that owns locale rather than in the installer body.
+install_phase = commons.PRE_PKGS_INSTALL
 enabled = True
 
 
 def execute(installer):
     # Set locale
-    with open(
-        os.path.join(installer.photon_root, "etc/locale.conf"), "w"
-    ) as locale_conf:
+    locale_conf_path = os.path.join(installer.photon_root, "etc/locale.conf")
+    os.makedirs(os.path.dirname(locale_conf_path), exist_ok=True)
+    with open(locale_conf_path, "w") as locale_conf:
         locale_conf.write("LANG=en_US.UTF-8\n")
-
-    """
-    locale-gen.sh needs /usr/share/locale/locale.alias which is shipped
-    with glibc-lang rpm, in some photon installations glibc-lang rpm is
-    not installed by default. Call localedef directly here to define
-    locale environment.
-    """
-    installer.cmd.run_in_chroot(
-        installer.photon_root,
-        "/usr/bin/localedef -c -i en_US -f UTF-8 en_US.UTF-8",
-    )

photon_installer/modules/m_localedef.py

@@ -0,0 +1,30 @@
+# /*
+# * Copyright © 2020 VMware, Inc.
+# * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-only
+# */
+
+import commons
+
+# The other half of locale setup, and the half that cannot move earlier.
+#
+# m_locale writes /etc/locale.conf at PRE_PKGS_INSTALL because dracut needs it
+# before the package transaction ends. localedef cannot follow it there: it runs
+# inside the chroot, and at PRE_PKGS_INSTALL the target holds only an
+# initialised rpm database and the `filesystem` rpm - glibc, which provides
+# /usr/bin/localedef, is not installed until _install_packages(). So this stays
+# at POST_INSTALL.
+install_phase = commons.POST_INSTALL
+enabled = True
+
+
+def execute(installer):
+    """
+    locale-gen.sh needs /usr/share/locale/locale.alias which is shipped
+    with glibc-lang rpm, in some photon installations glibc-lang rpm is
+    not installed by default. Call localedef directly here to define
+    locale environment.
+    """
+    installer.cmd.run_in_chroot(
+        installer.photon_root,
+        "/usr/bin/localedef -c -i en_US -f UTF-8 en_US.UTF-8",
+    )