diff --git a/remoteappmanager/file_config.py b/remoteappmanager/file_config.py
index 2f93478..8966ed8 100644
--- a/remoteappmanager/file_config.py
+++ b/remoteappmanager/file_config.py
@@ -3,7 +3,6 @@ import os
 import tornado.options
 from docker import tls
 from traitlets import HasTraits, Int, Unicode, Bool, Dict
-from traitlets.utils.sentinel import Sentinel
 
 from remoteappmanager import paths
 from remoteappmanager.traitlets import set_traits_from_dict
@@ -110,12 +109,7 @@ class FileConfig(HasTraits):
         for traitlet_name, traitlet in self.traits().items():
             # tornado.OptionParser defines an option with a Python type
             # and performs type validation.
-            # traitlet.default_value may be a Sentinel value (e.g. Tuple,
-            # Dict, Instance), in which case we use the repr
-            default_value = traitlet.default_value
-
-            if type(default_value) is Sentinel:
-                default_value = eval(traitlet.default_value_repr())
+            default_value = getattr(self, traitlet_name)
 
             file_line_parser.define(
                 traitlet_name,

FileConfig with tls=True or tls_verify=False only, leads to docker TLSParameterError 
On Linux, if my file config for the `remoteappmanager_config.py` ONLY contains the following:
```
$ cat remoteappmanager_config.py
tls = True
```

or
```
$ cat remoteappmanager_config.py
tls_verify = True
```

Then starting remoteappmanager gives this error
```
$ remoteappmanager --user=kit --port=45707 --cookie-name=jupyter-hub-token-kit --base-urlpath=/user/kit --hub-host= --hub-prefix=/hub/ --hub-api-url=http://172.16.253.129:8081/hub/api --ip=127.0.0.1 --proxy-api-url=http://127.0.0.1:8001/api/routes/ --config-file=remoteappmanager_config.py
...
[E 160720 14:33:43 web:1548] Uncaught exception GET /user/kit/ (127.0.0.1)
    HTTPServerRequest(protocol='http', host='127.0.0.1:8000', method='GET', uri='/user/kit/', version='HTTP/1.1', remote_ip='127.0.0.1', headers={'X-Forwarded-Proto': 'https', 'Accept-Language': 'en-US,en;q=0.5', 'X-Forwarded-For': '127.0.0.1', 'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8', 'If-None-Match': '"dfba4089bef9b2e40bbd2a75ba5413bb8edbdd83"', 'Host': '127.0.0.1:8000', 'User-Agent': 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:39.0) Gecko/20100101 Firefox/39.0', 'Referer': 'https://127.0.0.1:8000/hub/login', 'Accept-Encoding': 'gzip, deflate', 'Connection': 'close', 'X-Forwarded-Port': '8000', 'Cookie': 'jupyter-hub-token-kit="2|1:0|10:1469021623|21:jupyter-hub-token-kit|44:M2UzMjRlOGNhNDBjNGQ5ZWEwYjg3Njk0N2U0ODY4MmE=|1ec021fdad25b335a6b11b22ff198ce0860a0742a4d95c46a33a6d659d5f4e2d"'})
    Traceback (most recent call last):
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/traitlets/traitlets.py", line 501, in get
        value = obj._trait_values[self.name]
    KeyError: 'container_manager'
    
    During handling of the above exception, another exception occurred:
    
    Traceback (most recent call last):
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/tornado/web.py", line 1469, in _execute
        result = yield result
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/tornado/gen.py", line 1015, in run
        value = future.result()
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/tornado/concurrent.py", line 237, in result
        raise_exc_info(self._exc_info)
      File "<string>", line 3, in raise_exc_info
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/tornado/gen.py", line 1021, in run
        yielded = self.gen.throw(*exc_info)
      File "/mnt/hgfs/VM_shared/SimPhoNy/simphony-remote/remoteappmanager/handlers/home_handler.py", line 21, in get
        images_info = yield self._get_images_info()
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/tornado/gen.py", line 1015, in run
        value = future.result()
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/tornado/concurrent.py", line 237, in result
        raise_exc_info(self._exc_info)
      File "<string>", line 3, in raise_exc_info
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/tornado/gen.py", line 285, in wrapper
        yielded = next(result)
      File "/mnt/hgfs/VM_shared/SimPhoNy/simphony-remote/remoteappmanager/handlers/home_handler.py", line 184, in _get_images_info
        container_manager = self.application.container_manager
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/traitlets/traitlets.py", line 529, in __get__
        return self.get(obj, cls)
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/traitlets/traitlets.py", line 508, in get
        value = self._validate(obj, dynamic_default())
      File "/mnt/hgfs/VM_shared/SimPhoNy/simphony-remote/remoteappmanager/application.py", line 81, in _container_manager_default
        docker_config=self.file_config.docker_config()
      File "/mnt/hgfs/VM_shared/SimPhoNy/simphony-remote/remoteappmanager/file_config.py", line 155, in docker_config
        assert_hostname=True,
      File "/home/kit/.virtualenv/simremote/lib/python3.4/site-packages/docker/tls.py", line 47, in __init__
        'Path to a certificate and key files must be provided'
    docker.errors.TLSParameterError: Path to a certificate and key files must be provided through the client_config param. TLS configurations should map the Docker CLI client configurations. See https://docs.docker.com/engine/articles/https/ for API details.
```

diff --git a/tests/test_file_config.py b/tests/test_file_config.py
index 22ce879..484d1b9 100644
--- a/tests/test_file_config.py
+++ b/tests/test_file_config.py
@@ -151,3 +151,15 @@ class TestFileConfig(TempMixin, unittest.TestCase):
         config = FileConfig(tls=True)
         self.assertNotEqual(config.tls_key, '')
         self.assertNotEqual(config.tls_cert, '')
+
+    def test_file_parsing_not_overriding_bug_131(self):
+        docker_config = textwrap.dedent('''
+            tls = True
+            ''')
+        with open(self.config_file, 'w') as fhandle:
+            print(docker_config, file=fhandle)
+
+        config = FileConfig()
+        config.parse_config(self.config_file)
+        self.assertNotEqual(config.tls_key, '')
+        self.assertNotEqual(config.tls_cert, '')

pip install -e .[dev]
parse_log_pytest
requirements.txt
pytest flake8 sphinx coverage
apt-get update apt-get install -y gcc apt-get install -y docker.io
3.9
requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
alabaster==0.7.16
alembic==1.15.2
annotated-types==0.7.0
arrow==1.3.0
async-generator==1.10
attrs==25.3.0
babel==2.17.0
certifi==2025.1.31
certipy==0.2.2
cffi==1.17.1
charset-normalizer==3.4.1
click==8.1.8
coverage==7.8.0
cryptography==44.0.2
docker-py==1.10.6
docker-pycreds==0.4.0
docutils==0.21.2
escapism==1.0.1
exceptiongroup==1.2.2
flake8==7.2.0
fqdn==1.5.1
greenlet==3.1.1
idna==3.10
imagesize==1.4.1
importlib_metadata==8.6.1
iniconfig==2.1.0
isoduration==20.11.0
Jinja2==3.1.6
jsonpointer==3.0.0
jsonschema==4.23.0
jsonschema-specifications==2024.10.1
jupyter-events==0.12.0
jupyter_client==8.6.3
jupyter_core==5.7.2
jupyterhub==5.2.1
Mako==1.3.9
MarkupSafe==3.0.2
mccabe==0.7.0
oauthlib==3.2.2
packaging==24.2
pamela==1.2.0
platformdirs==4.3.7
pluggy==1.5.0
prometheus_client==0.21.1
pycodestyle==2.13.0
pycparser==2.22
pydantic==2.11.1
pydantic_core==2.33.0
pyflakes==3.3.1
Pygments==2.19.1
pytest==8.3.5
python-dateutil==2.9.0.post0
python-json-logger==3.3.0
PyYAML==6.0.2
pyzmq==26.3.0
referencing==0.36.2
-e git+https://github.com/simphony/simphony-remote.git@af0203df6cb3232a28b50fa1023baf73e234aa6d#egg=remoteappmanager
requests==2.32.3
rfc3339-validator==0.1.4
rfc3986-validator==0.1.1
rpds-py==0.24.0
six==1.17.0
snowballstemmer==2.2.0
Sphinx==7.4.7
sphinxcontrib-applehelp==2.0.0
sphinxcontrib-devhelp==2.0.0
sphinxcontrib-htmlhelp==2.1.0
sphinxcontrib-jsmath==1.0.1
sphinxcontrib-qthelp==2.0.0
sphinxcontrib-serializinghtml==2.0.0
SQLAlchemy==2.0.40
tabulate==0.9.0
tomli==2.2.1
tornado==6.4.2
traitlets==5.14.3
types-python-dateutil==2.9.0.20241206
typing-inspection==0.4.0
typing_extensions==4.13.0
uri-template==1.3.0
urllib3==2.3.0
webcolors==24.11.1
websocket-client==1.8.0
zipp==3.21.0

name: simphony-remote
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=3.0.16=h5eee18b_0
  - pip=25.0=py39h06a4308_0
  - python=3.9.21=he870216_1
  - readline=8.2=h5eee18b_0
  - setuptools=75.8.0=py39h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - tzdata=2025a=h04d1e81_0
  - wheel=0.45.1=py39h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - alabaster==0.7.16
      - alembic==1.15.2
      - annotated-types==0.7.0
      - arrow==1.3.0
      - async-generator==1.10
      - attrs==25.3.0
      - babel==2.17.0
      - certifi==2025.1.31
      - certipy==0.2.2
      - cffi==1.17.1
      - charset-normalizer==3.4.1
      - click==8.1.8
      - coverage==7.8.0
      - cryptography==44.0.2
      - docker-py==1.10.6
      - docker-pycreds==0.4.0
      - docutils==0.21.2
      - escapism==1.0.1
      - exceptiongroup==1.2.2
      - flake8==7.2.0
      - fqdn==1.5.1
      - greenlet==3.1.1
      - idna==3.10
      - imagesize==1.4.1
      - importlib-metadata==8.6.1
      - iniconfig==2.1.0
      - isoduration==20.11.0
      - jinja2==3.1.6
      - jsonpointer==3.0.0
      - jsonschema==4.23.0
      - jsonschema-specifications==2024.10.1
      - jupyter-client==8.6.3
      - jupyter-core==5.7.2
      - jupyter-events==0.12.0
      - jupyterhub==5.2.1
      - mako==1.3.9
      - markupsafe==3.0.2
      - mccabe==0.7.0
      - oauthlib==3.2.2
      - packaging==24.2
      - pamela==1.2.0
      - platformdirs==4.3.7
      - pluggy==1.5.0
      - prometheus-client==0.21.1
      - pycodestyle==2.13.0
      - pycparser==2.22
      - pydantic==2.11.1
      - pydantic-core==2.33.0
      - pyflakes==3.3.1
      - pygments==2.19.1
      - pytest==8.3.5
      - python-dateutil==2.9.0.post0
      - python-json-logger==3.3.0
      - pyyaml==6.0.2
      - pyzmq==26.3.0
      - referencing==0.36.2
      - requests==2.32.3
      - rfc3339-validator==0.1.4
      - rfc3986-validator==0.1.1
      - rpds-py==0.24.0
      - six==1.17.0
      - snowballstemmer==2.2.0
      - sphinx==7.4.7
      - sphinxcontrib-applehelp==2.0.0
      - sphinxcontrib-devhelp==2.0.0
      - sphinxcontrib-htmlhelp==2.1.0
      - sphinxcontrib-jsmath==1.0.1
      - sphinxcontrib-qthelp==2.0.0
      - sphinxcontrib-serializinghtml==2.0.0
      - sqlalchemy==2.0.40
      - tabulate==0.9.0
      - tomli==2.2.1
      - tornado==6.4.2
      - traitlets==5.14.3
      - types-python-dateutil==2.9.0.20241206
      - typing-extensions==4.13.0
      - typing-inspection==0.4.0
      - uri-template==1.3.0
      - urllib3==2.3.0
      - webcolors==24.11.1
      - websocket-client==1.8.0
      - zipp==3.21.0
prefix: /opt/conda/envs/simphony-remote

tests/test_file_config.py::TestFileConfig::test_file_parsing_not_overriding_bug_131
tests/test_file_config.py::TestFileConfig::test_initialization_on_local_docker_machine tests/test_file_config.py::TestFileConfig::test_initialization_on_nonlocal_docker_machine tests/test_file_config.py::TestFileConfig::test_initialization_with_default_accounting tests/test_file_config.py::TestFileConfig::test_initialization_with_good_accounting tests/test_file_config.py::TestFileConfig::test_overriding tests/test_file_config.py::TestFileConfig::test_tls_init tests/test_file_config.py::TestFileConfig::test_tls_no_verify
remoteappmanager/file_config.py
remoteappmanager/file_config.py