How to write to the console in Google App Engine?

Question

Often when I code, I just like to print small things (basically the current value of the variables) for the console. I don’t see anything like this for the Google App Engine, although I note that the Google App Engine Launcher has a log terminal. Is there a way to write to a Terminal or some other terminal using the Google App Engine?

Answer 1

You want to use the standard logging module of Python.

 import logging logging.info("hello") logging.debug("hi") # this won't show up by default 

To see the logging.debug() calls in the GoogleAppEngineLauncher Logs console, you must first add the --dev_appserver_log_level=debug flag to your application. However, be careful that you see a lot of noise debugging the App Engine SDK itself. complete set of levels :

• debug
• info
• warning
• error
• critical

You can add a flag by double-clicking the application and then dropping it in the Additional flags field.

Answer 2

See https://cloud.google.com/appengine/docs/python/requests#Python_Logging
and http://docs.python.org/library/logging.html

You probably want to use something like:

 logging.debug("value of my var is %s", str(var)) 

Answer 3

@Manjoor

You can do the same in java.

 import java.util.logging.Logger; // ... public class MyServlet extends HttpServlet { private static final Logger log = Logger.getLogger(MyServlet.class.getName()); public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException { log.info("An informational message."); log.warning("A warning message."); log.severe("An error message."); } } 

See “Registering” at http://code.google.com/appengine/docs/java/runtime.html

Answer 4

If you are using a newer version of Python Development Server (releases> 1.7.6 or Mar 2013 and later), these are apparently the right steps to use:

• Include the following in a script,

  import logging logging.debug("something I want to log")

• And for this page of documents, set the flag by choosing "Edit"> "Application Settings"> "Launch Options"> "Flags of additional commands", and adding,

  --log_level=debug

Answer 5

You should also take a look at FirePython. It allows you to receive server log messages in firebug.

http://appengine-cookbook.appspot.com/recipe/firepython-logger-console-inside-firebug/

Answer 6

Check out my online Python interpreter running on the Google App Engine on my website, Learn Python . Perhaps this is what you are looking for. Just use print repr (variable) for the things you want to see, and do as many times as you want.

Answer 7

Hello, I am using version 1.8.6 of GoogleAppEngineLauncher, you can use the flag to set the level of the message log that you want to see, for example, for debugging messages:

--dev_appserver_log_level debug

Use it instead of --debug (see @Christopher answer).

Answer 8

GAE will log a standard error and print it on the console or in a log.

 print >> sys.stderr, "Something to log." 

Answer 9

Use log.setLevel (Level.ALL) to view messages

The default message filtering level seems like an “error”. I did not see any useful log messages until I used the setLevel () method to make .info and .warning messages visible.

Text printed in System.out also did not display. This seems to be interpreted as log.info () level messaages.

Answer 10

I hope I answer this question. Log messages are printed in the AppEngine log, not in the terminal.

You can start it by clicking the log button in the AppEngine Launcher