Cannot find app logs using AppEngine's dev_appserver

[P.Y. Laligand]

(creating a separate topic for this question I had in my previous post)

So now that I have the appserver running correctly I'm trying to see what my server is doing by adding logs. Problem is, I can't find them anywhere. Here's what I see in my terminal:

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$ dev_appserver.py --custom_entrypoint "dart bin/server.dart {port}" --log_level=debug app.yaml

INFO     2016-03-18 16:22:18,994 application_configuration.py:431] No version specified. Generated version id: 20160318t162218

INFO     2016-03-18 16:22:18,995 devappserver2.py:769] Skipping SDK update check.

INFO     2016-03-18 16:22:19,034 api_server.py:205] Starting API server at: http://localhost:55738

INFO     2016-03-18 16:22:19,039 dispatcher.py:197] Starting module "default" running at: http://localhost:8080

INFO     2016-03-18 16:22:19,042 admin_server.py:116] Starting admin server at: http://localhost:8000

INFO     2016-03-18 16:22:20,054 module.py:1729] New instance for module "default" serving on:

http://localhost:8080

INFO     2016-03-18 16:22:20,094 module.py:787] default: "GET /_ah/start HTTP/1.1" 200 2

INFO     2016-03-18 16:22:26,009 module.py:787] default: "POST /trials HTTP/1.1" 200 31

INFO     2016-03-18 16:26:39,299 module.py:1768] [default] Detected file changes:

  /Users/pylaligand/Work/destiny/destiny-tools/slack-bot/bin/server.dart

INFO     2016-03-18 16:26:39,310 module.py:1893] Waiting for instances to restart

INFO     2016-03-18 16:26:40,320 module.py:1729] New instance for module "default" serving on:

http://localhost:8080

INFO     2016-03-18 16:26:40,363 module.py:787] default: "GET /_ah/start HTTP/1.1" 200 2

INFO     2016-03-18 16:26:40,374 module.py:1899] Instances restarted

INFO     2016-03-18 16:26:40,407 module.py:1768] [default] Detected file changes:

  /Users/pylaligand/Work/destiny/destiny-tools/slack-bot/bin/server.dart

INFO     2016-03-18 16:26:40,417 module.py:1893] Waiting for instances to restart

INFO     2016-03-18 16:26:41,430 module.py:1729] New instance for module "default" serving on:

http://localhost:8080

INFO     2016-03-18 16:26:41,469 module.py:787] default: "GET /_ah/start HTTP/1.1" 200 2

INFO     2016-03-18 16:26:41,473 module.py:1899] Instances restarted

INFO     2016-03-18 16:26:43,838 module.py:787] default: "POST /trials HTTP/1.1" 200 31

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All of these seem to be dev_appserver's logs, none are my app's.

I tried to use the --logs_path flag to redirect the logs database to a file, but only the RequestLogs table seems to be populated as the AppLogs table remains empty.

Looking at past post it used to be that |gcloud preview app run|'s verbosity needed to be set to debug for logs to show up. Is there an equivalent trick with dev_appserver?

[P.Y. Laligand]

Instant update: if I wrap runAppEngine in a withAppEngineServices call, then using the logging service does add entries to the AppLogs table. I still can't see anything in my terminal, nor do a Logger (with the adaptor for AE) or a |print| call create any entry.

[Daniel Domberger]

Heya,

we've run into this problem as well. Our solution was to only ever log into logfiles (and `tail -f` them as needed). There also is or was a bug in the communication between dev_appserver and the dart appengine lib where messages in the stdout buffer wouldn't be consumed. This lead to dev_appserver hang after a certain amount of messages sent to stdout. Søren Gjesse was kind enough to find the issue (we only saw dev_appserver randomly locking up). Here again the workaround was to never ever write to stdout but only to logfiles. Don't know if this is still relevant though.

Best regards
daniel

[Tony Downey]

Having a problem with this as well. Trying to log messages to the terminal when I run a server, but the following commands all have no effect:
print(msg);
context.services.logging.info(msg);
loggingService.info(msg);

Tried the same while running the flags:
--dev_appserver_log_level debug
--log_level debug

No change.

Quickest way to reproduce this bug - run the Cloud Datastore sample at https://github.com/dart-lang/appengine_samples

So yeah, the workaround for the moment is to create your own records of logs. Not super ideal.