jobdata: Use json to store args

Currently we dump args using pickle, which tries to pickle all objects.
This could fail between versions or even between instances (eg. with
different set of plugins). Let's just use safe json serialization
replacing unsafe objects with None to avoid unnecessary crashes while
still being able to make the safe information available.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

avocado/core/jobdata.py

@@ -18,6 +18,7 @@ Record/retrieve job information
 
 import ast
 import glob
+import json
 import os
 import pickle
 
@@ -49,7 +50,7 @@ def record(args, logdir, mux, references=None, cmdline=None):
                                           TEST_REFERENCES_FILENAME_LEGACY)
     path_mux = os.path.join(base_dir, VARIANTS_FILENAME)
     path_pwd = os.path.join(base_dir, PWD_FILENAME)
-    path_args = os.path.join(base_dir, ARGS_FILENAME)
+    path_args = os.path.join(base_dir, ARGS_FILENAME + ".json")
     path_cmdline = os.path.join(base_dir, CMDLINE_FILENAME)
 
     if references:
@@ -75,7 +76,7 @@ def record(args, logdir, mux, references=None, cmdline=None):
         os.fsync(pwd_file)
 
     with open(path_args, 'w') as args_file:
-        pickle.dump(args.__dict__, args_file, pickle.HIGHEST_PROTOCOL)
+        json.dump(args.__dict__, args_file, default=lambda x: None)
         args_file.flush()
         os.fsync(args_file)
 
@@ -136,9 +137,15 @@ def retrieve_args(resultsdir):
     """
     Retrieves the job args from the results directory.
     """
+    recorded_args = _retrieve(resultsdir, ARGS_FILENAME + ".json")
+    if recorded_args:
+        with open(recorded_args, 'r') as args_file:
+            return json.load(args_file)
     recorded_args = _retrieve(resultsdir, ARGS_FILENAME)
     if recorded_args is None:
         return None
+    # old pickle-based dump
+    # TODO: Remove when 36lts is discontinued
     with open(recorded_args, 'r') as args_file:
         return pickle.load(args_file)
 

avocado/plugins/replay.py

@@ -254,14 +254,9 @@ class Replay(CLI):
                 LOG_UI.error('Source job variants data not found. Aborting.')
                 sys.exit(exit_codes.AVOCADO_FAIL)
             else:
-                # Ignore data manipulation. This is necessary, because
-                # we replaced the unparsed object with parsed one. There
-                # are other plugins running before/after this which might
-                # want to alter the variants object.
-                if args.avocado_variants.is_parsed():
-                    LOG_UI.warning("Using src job Mux data only, use "
-                                   "`--replay-ignore variants` to override "
-                                   "them.")
+                LOG_UI.warning("Using src job Mux data only, use "
+                               "`--replay-ignore variants` to override "
+                               "them.")
                 setattr(args, "avocado_variants", variants)
 
         # Extend "replay_test_status" of "INTERRUPTED" when --replay-resume

selftests/functional/test_replay_basic.py

@@ -60,8 +60,8 @@ class ReplayTests(unittest.TestCase):
         """
         Checks if all expected files are there.
         """
-        file_list = ['variants', 'config', 'test_references', 'pwd', 'args',
-                     'cmdline']
+        file_list = ['variants', 'config', 'test_references', 'pwd',
+                     'args.json', 'cmdline']
         for filename in file_list:
             path = os.path.join(self.jobdir, 'jobdata', filename)
             self.assertTrue(glob.glob(path))