Fix logs encoding in py3

Make sure that logs are encoded as text (not byte strings) in
python3 to allow theirs serialization in JSON.

Closes-Bug: #1668533

Change-Id: I3d0d87ca766146457d905f89c26331a415bd54f8

ironic_python_agent/tests/unit/test_utils.py

@@ -27,6 +27,7 @@ import mock
 from oslo_concurrency import processutils
 from oslo_serialization import base64
 from oslotest import base as test_base
+import six
 import testtools
 
 from ironic_python_agent import errors
@@ -385,6 +386,7 @@ class TestUtils(testtools.TestCase):
         contents = b'Squidward Tentacles'
         io_dict = {'fake-name': io.BytesIO(bytes(contents))}
         data = utils.gzip_and_b64encode(io_dict=io_dict)
+        self.assertIsInstance(data, six.text_type)
 
         res = io.BytesIO(base64.decode_as_bytes(data))
         with tarfile.open(fileobj=res) as tar:

ironic_python_agent/utils.py

@@ -383,7 +383,7 @@ def gzip_and_b64encode(io_dict=None, file_list=None):
                 tar.add(f)
 
         fp.seek(0)
-        return base64.encode_as_bytes(fp.getvalue())
+        return base64.encode_as_text(fp.getvalue())
 
 
 def collect_system_logs(journald_max_lines=None):

releasenotes/notes/fix-bytes-json-serializable-collected-logs-ad61022b287dc3e2.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - JSON serialization of logs collected for ironic-python-agent.
+    In python3 logs were encoded as byte strings, which can't be serialized.
+    Make sure that logs are encoded as text for both py2.7 and py3. See
+    https://bugs.launchpad.net/ironic-python-agent/+bug/1668533 for details.