curtin-replay: improve CLI of replay-curtin-log

We now use argparse on replay-curtin-log, which provides the --help
option along with named parameters for what used to be positional
parameters only.

Signed-off-by: Olivier Gayot <olivier.gayot@canonical.com>

scripts/replay-curtin-log.py

@@ -1,16 +1,18 @@
 #!/usr/bin/python3
 
+""" Script that replays curtin events from a journald export.
+curtin events are injected back in journald and log lines are written to a log
+file. """
+
+import argparse
 import json
 import os
 import sys
 import time
+from typing import TextIO
 
 from systemd import journal
 
-json_file = sys.argv[1]
-event_identifier = sys.argv[2]
-log_location = sys.argv[3]
-
 scale_factor = float(os.environ.get('SUBIQUITY_REPLAY_TIMESCALE', "4"))
 
 def time_for_entry(e):
@@ -18,7 +20,7 @@ def time_for_entry(e):
 
 rc = 0
 
-def report(e, log_file):
+def report(e, log_file: TextIO, event_identifier: str):
     global rc
     if e['SYSLOG_IDENTIFIER'].startswith("curtin_event"):
         e['SYSLOG_IDENTIFIER'] = event_identifier
@@ -30,18 +32,31 @@ def report(e, log_file):
         elif r == "FAIL":
             rc = 1
     elif e['SYSLOG_IDENTIFIER'].startswith("curtin_log") and scale_factor < 10:
-        print(e['MESSAGE'], flush=True)
         log_file.write(e['MESSAGE'] + '\n')
 
-with open(log_location, 'w') as fp:
+
+def main() -> int:
+    """ Entry point. """
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument("replay-file")
+    parser.add_argument("--event-identifier", required=True)
+    parser.add_argument("--output", type=argparse.FileType("w"), default="-")
+
+    args = vars(parser.parse_args())
+
     prev_ev = None
-    for line in open(json_file):
+    for line in open(args["replay-file"]):
         ev = json.loads(line.strip())
         if prev_ev is not None:
-            report(prev_ev, fp)
+            report(prev_ev, args["output"],
+                   event_identifier=args["event_identifier"])
             delay = time_for_entry(ev) - time_for_entry(prev_ev)
             time.sleep(min(delay, 8)/scale_factor)
         prev_ev = ev
-    report(ev, fp)
+    report(ev, args["output"], event_identifier=args["event_identifier"])
+    return rc
 
-sys.exit(rc)
+
+if __name__ == "__main__":
+    sys.exit(main())

subiquity/server/curtin.py

@@ -139,9 +139,10 @@ class _DryRunCurtinCommand(_CurtinCommand):
             return [
                 sys.executable,
                 "scripts/replay-curtin-log.py",
+                "--event-identifier", self._event_syslog_id,
+                "--output", self.opts.output_base + INSTALL_LOG,
+                "--",
                 self.event_file,
-                self._event_syslog_id,
-                self.opts.output_base + INSTALL_LOG,
                 ]
         else:
             return super().make_command(command, *args, config=config)