Gremlin server can not be started on local machine (in Docker)

[tisnik]

bayesian-gremlin-http   | 21457 [gremlin-server-boss-1] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - Gremlin Server configured with worker thread pool of 1, gremlin pool of 8 and boss thread pool of 1.
bayesian-gremlin-http   | 21458 [gremlin-server-boss-1] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - Channel started at port 8182.
data-model-importer_1   | [2017-06-08 15:22:29 +0000] [7] [INFO] Starting gunicorn 19.7.1
data-model-importer_1   | [2017-06-08 15:22:29 +0000] [7] [INFO] Listening at: http://0.0.0.0:9192 (7)
data-model-importer_1   | [2017-06-08 15:22:29 +0000] [7] [INFO] Using worker: sync
data-model-importer_1   | [2017-06-08 15:22:29 +0000] [12] [INFO] Booting worker with pid: 12
data-model-importer_1   | [2017-06-08 15:22:30 +0000] [12] [ERROR] Exception in worker process
data-model-importer_1   | Traceback (most recent call last):
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/gunicorn/arbiter.py", line 578, in spawn_worker
data-model-importer_1   |     worker.init_process()
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/gunicorn/workers/base.py", line 126, in init_process
data-model-importer_1   |     self.load_wsgi()
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/gunicorn/workers/base.py", line 135, in load_wsgi
data-model-importer_1   |     self.wsgi = self.app.wsgi()
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/gunicorn/app/base.py", line 67, in wsgi
data-model-importer_1   |     self.callable = self.load()
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/gunicorn/app/wsgiapp.py", line 65, in load
data-model-importer_1   |     return self.load_wsgiapp()
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/gunicorn/app/wsgiapp.py", line 52, in load_wsgiapp
data-model-importer_1   |     return util.import_app(self.app_uri)
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/gunicorn/util.py", line 352, in import_app
data-model-importer_1   |     __import__(module)
data-model-importer_1   |   File "/src/rest_api.py", line 23, in <module>
data-model-importer_1   |     if not BayesianGraph.is_index_created():
data-model-importer_1   |   File "/src/graph_manager.py", line 76, in is_index_created
data-model-importer_1   |     status, json_result = cls.execute(str_gremlin_dsl)
data-model-importer_1   |   File "/src/graph_manager.py", line 48, in execute
data-model-importer_1   |     data=json.dumps(payload))
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/requests/api.py", line 112, in post
data-model-importer_1   |     return request('post', url, data=data, json=json, **kwargs)
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/requests/api.py", line 58, in request
data-model-importer_1   |     return session.request(method=method, url=url, **kwargs)
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/requests/sessions.py", line 513, in request
data-model-importer_1   |     resp = self.send(prep, **send_kwargs)
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/requests/sessions.py", line 623, in send
data-model-importer_1   |     r = adapter.send(request, **kwargs)
data-model-importer_1   |   File "/usr/lib/python2.7/site-packages/requests/adapters.py", line 504, in send
data-model-importer_1   |     raise ConnectionError(e, request=request)
data-model-importer_1   | ConnectionError: HTTPConnectionPool(host='bayesian-gremlin-http', port=8182): Max retries exceeded with url: / (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x38ae510>: Failed to establish a new connection: [Errno 111] Connection refused',))

[miteshvp]

@tisnik - so its an expected behavior. Gremlin-http takes some time to start before serving any requests. Data_importer depends on Gremlin-http. So after some time, when gremlin-http is up fully, data_importer is also started properly. Unfortunately, docker does not give the flexibility to wait until one container is ready to serve requests. They know this (docker/compose#374). We could have fixed this start-up all by ourselves with a script or in data_importer codebase itself, but sooner or later, data_importer will be part of selinon tasks, so thought against it.
Previous issue - fabric8-analytics/fabric8-analytics-common#19

[tisnik]

@miteshvp thank you very much for explanation. Do you think it is worth to mention this behaviour in the documentation (as an admonition, for example)?

[miteshvp]

Yes, thats a good suggestion. Can you raise a PR for the same?

[tisnik]

@miteshvp yes I'll do it. Thanks!

[fridex]

Fixed by #34