Flow of the backend of homeassistant

Development
1

I downloaded home assistant source code of backend from github.

I added some prints and logs in main , bootstrap and core in order to debug the code.

All the prints added in main are visible on console when I run the following command:
python3 main --open-ui

But I am unable to receive the prints added in the other files. Also I even removed core.py but still the home assistant web ui gets opened.

Can you please tell me why I cannot add print statements in these files…From where it is executing core.py if I removed it from the source code folder…How can I debug and understand the flow of this source code?

2

You could use a tool to create a call graph or check the imports to see where a given part is used like core.

3

can you suggest a tool for this ? @fabaff

4

@fabaff

Can you let us know, in which directory, the logs received after running python3 main.py --open-ui are getting saved?

This can help us to add and view some logs in core.py and debug them.

5

No, but there are pycallgraph and pyan perhaps one of those can help even if they are not able to catch all the dynamic stuff.

Configuration folder

6

@fabaff

Intsalled pycallgraph and tried executing a script using this module. Getting this error:

Traceback (most recent call last):
  File "/home/ayushi/.local/bin/pycallgraph", line 25, in <module>
    with __pycallgraph.PyCallGraph(config=__config):
  File "/home/ayushi/.local/lib/python3.5/site-packages/pycallgraph/pycallgraph.py", line 32, in __init__
    self.reset()
  File "/home/ayushi/.local/lib/python3.5/site-packages/pycallgraph/pycallgraph.py", line 53, in reset
    self.prepare_output(output)
  File "/home/ayushi/.local/lib/python3.5/site-packages/pycallgraph/pycallgraph.py", line 97, in prepare_output
    output.sanity_check()
  File "/home/ayushi/.local/lib/python3.5/site-packages/pycallgraph/output/graphviz.py", line 63, in sanity_check
    self.ensure_binary(self.tool)
  File "/home/ayushi/.local/lib/python3.5/site-packages/pycallgraph/output/output.py", line 97, in ensure_binary
    'The command "{}" is required to be in your path.'.format(cmd))
pycallgraph.exceptions.PyCallGraphException: The command "dot" is required to be in your path.
7

Can you please let me know which all files and directories are included in the REST API(services) creation of backend code of home assistant.

Also, how can I create some more new APIs and call services with those APIs?

8

One of the first hits with a search engine: pycallgraph.exceptions.PyCallGraphException · Issue #177 · gak/pycallgraph · GitHub

There are some API endpoints api.py which are for Home Assistant itself and some are created by integrations. Search inside the source code for /api/.

API endpoints are inheriting from HomeAssistantView which is part of the http component. just create a new custom_component to handle a new API call.