Say I have a folder structure like this
custom_py_package1
- __init.py__
- ...
custom_py_package2
- __init.py__
- ...
app
- streamlit_app1.py
- ...
I want to run apps from my app folder which uses custom_py_package1 and custom_py_package2. Now that all works fine but I’d like my apps to detect changes in my custom packages without restarting the app. How do I achieve this?
Hi @mr-bjerre, thanks for your question. By default Streamlit only watches modules within the directory of the main script file. In your case, that would be app.
Nevertheless, Streamlit also watches modules in the PYTHONPATH. So setting the PYTHONPATH to include the modules you want to track should help you.
See this PR: https://github.com/streamlit/streamlit/pull/845
Best,
Matteo
@monchier is this currently working? I’m modifying a function foo inside $ROOT/mypackage/func.py
and my streamlit app file is in $ROOT/utils/streamlit_main.py
When doing
export PYTHONPATH = $ROOT/mypackage/func.py
streamlit run $ROOT/utils/streamlit_main.py
If I modify function foo inside func.py, streamlit doesn’t detect the changes in the main app.
I have a similar problem. I have two folders , lets call them “my_folder1” and “my_folder2”
My Dockerfile has
ENV PYTHONPATH=./
ENTRYPOINT ["streamlit", "run"]
CMD ["./my_folder2/main.py"]
but the app does not watch for changes in ./my_folder1/ 
It seems that the issue was not importing directly the function, but rather importing the module.
What I’m currently doing is the following:
import inspect
import os
import streamlit as st
from streamlit import session_state as st_session
from mypackage.module import foo, bar
def monitor_func(*args):
if 'monitor' not in st_session:
st_session['monitor'] = set()
for func in args:
path = inspect.getsourcefile(func)
st_session['monitor'].add(os.path.dirname(path))
os.environ['PYTHONPATH'] = ':'.join(list(st_session['monitor']))
monitor_func(foo, bar)
foo()
bar()
Then changes in foo and bar are detected in the main app.
But if I do:
import inspect
import os
import streamlit as st
from streamlit import session_state as st_session
from mypackage import module
def monitor_func(*args):
if 'monitor' not in st_session:
st_session['monitor'] = set()
for func in args:
path = inspect.getsourcefile(func)
st_session['monitor'].add(os.path.dirname(path))
os.environ['PYTHONPATH'] = ':'.join(list(st_session['monitor']))
monitor_func(module.foo, module.bar)
module.foo()
module.bar()
Then changes are not detected
created an issue here which i will also be resolving
I created a PR for this