Merge pull request #2064 from ogayot/systemd-shutdown

storage: lean on systemd-shutdown to export zpools on shutdown

subiquity/models/filesystem.py

@@ -2053,6 +2053,13 @@ def render(self, mode: ActionRenderMode = ActionRenderMode.DEFAULT):
             config["grub"] = self.grub
         return config
 
+    def systemd_shutdown_commands(self) -> list[list[str]]:
+        """Return a list of commands meant to be executed by systemd-shutdown.
+        We entrust the execution of `zpool export` commands to systemd-shutdown
+        instead of subiquity's _pre_shutdown hook, in hope that the commands
+        will more likely succeed."""
+        return [["zpool", "export", zpool.name] for zpool in self._all(type="zpool")]
+
     def load_probe_data(self, probe_data):
         for devname, devdata in probe_data["blockdev"].items():
             if int(devdata["attrs"]["size"]) != 0:

subiquity/server/controllers/filesystem.py

@@ -1765,5 +1765,3 @@ async def _pre_shutdown(self):
                 )
             else:
                 await self.app.command_runner.run(["umount", "--recursive", "/target"])
-        if len(self.model._all(type="zpool")) > 0:
-            await self.app.command_runner.run(["zpool", "export", "-a"])

subiquity/server/controllers/install.py

@@ -345,6 +345,25 @@ async def curtin_install(self, *, context, source):
 
         fs_controller = self.app.controllers.Filesystem
 
+        def register_shutdown_commands() -> None:
+            cmds: list[list[str]] = fs_controller.model.systemd_shutdown_commands()
+
+            if not cmds:
+                return
+
+            shutdown_dir = root / "usr/lib/systemd/system-shutdown"
+            shutdown_script = shutdown_dir / "subiquity-storage.shutdown"
+            shutdown_dir.mkdir(parents=True, exist_ok=True)
+            with shutdown_script.open(mode="w", encoding="utf-8") as stream:
+                # Generating a bash script is .. ewww
+                # Should we place the commands in a JSON file and hardcode a
+                # script that calls jq or something?
+                stream.write("#!/bin/bash\n")
+                for cmd in cmds:
+                    stream.write(shlex.join(cmd))
+                    stream.write("\n")
+            shutdown_script.chmod(0o755)
+
         async def run_curtin_step(name, stages, step_config, source=None):
             config = copy.deepcopy(base_config)
             filename = f"subiquity-{name.replace(' ', '-')}.conf"
@@ -368,6 +387,7 @@ async def run_curtin_step(name, stages, step_config, source=None):
                     device_map_path=logs_dir / "device-map.json",
                 ),
             )
+            register_shutdown_commands()
         elif fs_controller.use_snapd_install_api():
             await run_curtin_step(
                 name="partitioning",
@@ -387,6 +407,7 @@ async def run_curtin_step(name, stages, step_config, source=None):
                     device_map_path=logs_dir / "device-map-format.json",
                 ),
             )
+            register_shutdown_commands()
             if source is not None:
                 await run_curtin_step(
                     name="extract",
@@ -420,6 +441,7 @@ async def run_curtin_step(name, stages, step_config, source=None):
                 ),
                 source=source,
             )
+            register_shutdown_commands()
             await run_curtin_step(
                 name="extract",
                 stages=["extract"],