devstack-101/Debugging hints.rst at master · UTSA-ICS/devstack-101

URL Routing

For routing of URL to method name look at this file on nova server: /opt/stack/nova/nova/api/openstack/compute/__init__.py

To understand how this works read these 2 links: http://docs.openstack.org/developer/nova/devref/addmethod.openstackapi.html#routing http://docs.openstack.org/developer/nova/devref/addmethod.openstackapi.html#controllers-and-actions

This is a the doc for the routes module that is used to implement the URL routing in openstack. Read this thoroughly! https://routes.readthedocs.org/en/latest/introduction.html

https://routes.readthedocs.org/en/latest/glossary.html

Traceback

Add traceback to the code and check the stack trace to see code path:

# Add the following line to the import section of a python file you are looking at
import traceback

# Add the following line to the any location where you want the stack to be printed
traceback.print_stack()

File/content search tips

To search for a file ‘foo’ under the current directory (recursive search)
        find . |grep foo
To search for a keyword ‘bar’ (case insensitive “-i”) under the current directory (recursive search “-r”),
        grep -i -r bar *
        grep -i -r bar * |grep -v tests ---> (“-v” says exclude this from my search)

Run nova api such that it is logged to a terminal

screen -r stack
Ctrl+a+n        -> Use the control command (a+n) to go to ‘n-api’ (Nova API)
Ctrl+C          -> to stop Nova API process
Now use the "up" arrow to get the startup script for nova api.
In this case pressing the "up" arrow shows the following script:
        cd /opt/stack/nova && /opt/stack/nova/bin/nova-api > /tmp/nova_api.log 2>&1
Open a new terminal and paste the nova api startup script:
        cd /opt/stack/nova && /opt/stack/nova/bin/nova-api > /tmp/nova_api.log 2>&1
Logs are now being written to /tmp/nova_api.log file.
Ctrl+a+d        -> to exit out of screen
you can now run ‘less’ on the log file to search through it.
less /tmp/nova_api.log
Ctrl+F          -> in ‘less’ to update the file with live data
Ctrl+C          -> to cancel and go back to search mode in ‘less’