<p>Is it possible? 
By debug I mean setting breakpoints, inspect values and advance step by step.</p>

I haven't used web2py, but if it runs in a terminal window, you can use standard pdb stuff. Add this line somewhere in your code:
```
```
import pdb; pdb.set_trace()
```
```
This will invoke the debugger and break.  Then you can use
PDB
commands: n to step to the next line, l to list code, s to step into a function, p to print values, etc.