How can I start a python subprocess command on linux shell from within Django web app?

Question

I have a web app which reads and displays log files generated by python test files. Currently I can launch the python files from cli and it works fine.

However I would like to be able to launch python tests from within the application.

At the minute I have a "Launch test" button which calls a function in the views.py file

def launch_tests(request, test_txt_file):
    test_list_file = test_txt_file
    launcher2.main(test_list_file)

    return render_to_response('front_page.html')

The text file contains the names of the .py files to be executed

In launcher2.main

import os,time, string, pdb, sys
import getopt,subprocess
import pdb

bi_python_home = '//belfiler1/scratch-disk/conor.doherty/dev/python/bi_python'


def main(test_list_file):

    # if argument passed in for test list file  
    if test_list_file != None:
        test_list = bi_python_home + "/launcher/" + test_list_file
    else:
        # default
        test_list =  bi_python_home + "/launcher/test_list.txt"



    tests_dir =  bi_python_home + "/tests/"
    log_dir =bi_python_home + "/logs/"
    month = '%Y%m'
    day = '%d'
    try :
        for test_to_run in open(test_list):
            sub_dir=os.path.dirname(test_to_run) 
            test_filename = os.path.basename(test_to_run)

            # Create log directory for date if doesn't exist
            cur_log_dir = log_dir + time.strftime(month, time.localtime()) + '/' + time.strftime(month+day, time.localtime()) + '/' + sub_dir 
            if not os.path.exists(cur_log_dir):
                print "creating cur_log_dir "  + cur_log_dir
                os.makedirs(cur_log_dir)


            full_path = string.rstrip(tests_dir + test_to_run)
            #print ' full_path is "' + full_path + '"'
            cmd = 'python ' + full_path


            if os.path.isfile(full_path) == True :
                print'\n'*2
                print "Processing file " + test_to_run,

                log_timestamp = time.strftime("%Y%m%d_%H%M%S", time.localtime())
                log_filename = cur_log_dir + '/' + string.rstrip(test_filename) + "_" + log_timestamp + '.log' 
                print 'log file to use is' + log_filename
                # Redirect stdout and stderr to logfile
                cmd = string.rstrip(cmd) + ' > ' + log_filename
                popen_obj = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
                (stdout, stderr) = popen_obj.communicate()
                print 'executing: ' + cmd
                print 'stderr is: ', stderr





            # if need to debug , remove stream redirection &> above and print stdout, stderr

        #else :
            #print 'ignoring ' , full_path



except IOError, err:
    print str(err) 
    sys.exit(2)

The Code works fine apart from one thing. When I kick off the subprocess it seems to be executed on windows by default. Since the tests use a module called pexpect i need it to be executed on linux.

I keep thinking there has to be a simple solution but so far I have had no luck.

Any help would be greatly appreciated,

Thanks

Answer 1

There is not enough information here to give a proper answer, but a common problem here is that the web front-end (eg apache) is running as a different user than what you run under. Therefore the web handler doesn't have the permissions to ready the files in your home directory. It probably also lacks some important environment variables, such as HOME.

Check that out, first. What do the web server logs say?