python example do not works

[bioinfornatics]

I followed instruction from python.md

I got an error while trying to follow the code:

GremlinServerError: 499: The traversal source [g] for alias [g] is not configured on the server.

how to reproduce:

mkdir  janusgraph
# podamn or docker is same
podman run --rm -d --name janusgraph_server -v "${PWD}"/janusgraph:/var/lib/janusgraph -p 8182:8182 docker.io/janusgraph/janusgraph:0.5.3

sudo apt install python3.8-venv
python3 -m venv janusgraph_env
source janusgraph_env/bin/activate
pip3 install wheel
pip3 install gremlinpython==3.4.6
ipython3 # <<-- start here

[li-boxuan]

The link you provided is for the 0.6.0 version (which is not released yet), while you are pulling JanusGraph 0.5.3 version. You should follow the steps on https://docs.janusgraph.org/connecting/python/

[bioinfornatics]

@li-boxuan thanks for your quick answer.
I tried too this example with same results

1. Check that janusgraph is up

$ podman ps -a
CONTAINER ID  IMAGE                                  COMMAND     CREATED       STATUS           PORTS                   NAMES
861da817cdc5  docker.io/janusgraph/janusgraph:0.5.3  janusgraph  46 hours ago  Up 46 hours ago  0.0.0.0:8182->8182/tcp  janusgraph_server

2. Start python code

$ ipython3
In [1]: from gremlin_python import statics 
   ...: from gremlin_python.structure.graph import Graph 
   ...: from gremlin_python.process.graph_traversal import __ 
   ...: from gremlin_python.driver.driver_remote_connection import DriverRemoteConnection 
   ...:  
   ...:                                                                                                                                                                                                    

In [2]: graph = Graph() 
   ...: connection = DriverRemoteConnection('ws://localhost:8182/gremlin', 'g') 
   ...: # The connection should be closed on shut down to close open connections with connection.close() 
   ...: g = graph.traversal().withRemote(connection) 
   ...: # Reuse 'g' across the application 
   ...:  
   ...:                                                                                                                                                                                                    

In [3]: herculesAge = g.V().has('name', 'hercules').values('age').next() 
   ...: print('Hercules is {} years old.'.format(herculesAge))                                                                                                                                             
---------------------------------------------------------------------------
GremlinServerError                        Traceback (most recent call last)
<ipython-input-3-9be2a9a86741> in <module>
----> 1 herculesAge = g.V().has('name', 'hercules').values('age').next()
      2 print('Hercules is {} years old.'.format(herculesAge))

~/janusgraph_env/lib/python3.8/site-packages/gremlin_python/process/traversal.py in next(self, amount)
     86     def next(self, amount=None):
     87         if amount is None:
---> 88             return self.__next__()
     89         else:
     90             count = 0

~/janusgraph_env/lib/python3.8/site-packages/gremlin_python/process/traversal.py in __next__(self)
     45     def __next__(self):
     46         if self.traversers is None:
---> 47             self.traversal_strategies.apply_strategies(self)
     48         if self.last_traverser is None:
     49             self.last_traverser = next(self.traversers)

~/janusgraph_env/lib/python3.8/site-packages/gremlin_python/process/traversal.py in apply_strategies(self, traversal)
    542     def apply_strategies(self, traversal):
    543         for traversal_strategy in self.traversal_strategies:
--> 544             traversal_strategy.apply(traversal)
    545 
    546     def apply_async_strategies(self, traversal):

~/janusgraph_env/lib/python3.8/site-packages/gremlin_python/driver/remote_connection.py in apply(self, traversal)
     61     def apply(self, traversal):
     62         if traversal.traversers is None:
---> 63             remote_traversal = self.remote_connection.submit(traversal.bytecode)
     64             traversal.remote_results = remote_traversal
     65             traversal.traversers = remote_traversal.traversers

~/janusgraph_env/lib/python3.8/site-packages/gremlin_python/driver/driver_remote_connection.py in submit(self, bytecode)
     58     def submit(self, bytecode):
     59         result_set = self._client.submit(bytecode, request_options=self._extract_request_options(bytecode))
---> 60         results = result_set.all().result()
     61         return RemoteTraversal(iter(results))
     62 

/usr/lib/python3.8/concurrent/futures/_base.py in result(self, timeout)
    442                     raise CancelledError()
    443                 elif self._state == FINISHED:
--> 444                     return self.__get_result()
    445                 else:
    446                     raise TimeoutError()

/usr/lib/python3.8/concurrent/futures/_base.py in __get_result(self)
    387         if self._exception:
    388             try:
--> 389                 raise self._exception
    390             finally:
    391                 # Break a reference cycle with the exception in self._exception

~/janusgraph_env/lib/python3.8/site-packages/gremlin_python/driver/resultset.py in cb(f)
     88         def cb(f):
     89             try:
---> 90                 f.result()
     91             except Exception as e:
     92                 future.set_exception(e)

/usr/lib/python3.8/concurrent/futures/_base.py in result(self, timeout)
    435                     raise CancelledError()
    436                 elif self._state == FINISHED:
--> 437                     return self.__get_result()
    438 
    439                 self._condition.wait(timeout)

/usr/lib/python3.8/concurrent/futures/_base.py in __get_result(self)
    387         if self._exception:
    388             try:
--> 389                 raise self._exception
    390             finally:
    391                 # Break a reference cycle with the exception in self._exception

/usr/lib/python3.8/concurrent/futures/thread.py in run(self)
     55 
     56         try:
---> 57             result = self.fn(*self.args, **self.kwargs)
     58         except BaseException as exc:
     59             self.future.set_exception(exc)

~/janusgraph_env/lib/python3.8/site-packages/gremlin_python/driver/connection.py in _receive(self)
     81             while True:
     82                 data = self._transport.read()
---> 83                 status_code = self._protocol.data_received(data, self._results)
     84                 if status_code != 206:
     85                     break

~/janusgraph_env/lib/python3.8/site-packages/gremlin_python/driver/protocol.py in data_received(self, message, results_dict)
    129         else:
    130             del results_dict[request_id]
--> 131             raise GremlinServerError(message['status'])
    132 
    133     def _kerberos_received(self, message):

GremlinServerError: 499: The traversal source [g] for alias [g] is not configured on the server.

[bioinfornatics]

I tried to do a query in groovy... with a fail too... arf

1. start janusgraph into a pod named jgpod

$ podman run --rm -dt --name janusgraph_server -v "${PWD}"/janusgraph:/var/lib/janusgraph --pod new:jgpod -p 0.0.0.0:8182:8182 docker.io/janusgraph/janusgraph:0.5.3

2. start gremlin into the pod jgpod

$ podman  run --rm --pod jgpod -it docker.io/janusgraph/janusgraph:0.5.3 ./bin/gremlin.sh
Jul 22, 2021 2:43:39 PM java.util.prefs.FileSystemPreferences$1 run
INFO: Created user preferences directory.

         \,,,/
         (o o)
-----oOOo-(3)-oOOo-----
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/opt/janusgraph/lib/slf4j-log4j12-1.7.12.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/opt/janusgraph/lib/logback-classic-1.1.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
plugin activated: tinkerpop.server
plugin activated: tinkerpop.tinkergraph
14:43:45 WARN  org.apache.hadoop.util.NativeCodeLoader  - Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
plugin activated: tinkerpop.hadoop
plugin activated: tinkerpop.spark
plugin activated: tinkerpop.utilities
plugin activated: janusgraph.imports

3. We are now into the container, configure the remote

gremlin> :remote connect tinkerpop.server conf/remote.yaml
==>Configured localhost/127.0.0.1:8182

4. Add vertice

gremlin> :> g.addV('person').property('name', 'chris')
gremlin-groovy is not an available GremlinScriptEngine

gremlin code took here: https://github.com/JanusGraph/janusgraph-docker

[li-boxuan]

I tried https://github.com/JanusGraph/janusgraph-docker#usage and it worked well as documented.

Step 1:
docker run --rm --name janusgraph-default docker.io/janusgraph/janusgraph:latest

Step 2:
docker run --rm --link janusgraph-default:janusgraph -e GREMLIN_REMOTE_HOSTS=janusgraph \ -it docker.io/janusgraph/janusgraph:latest ./bin/gremlin.sh

If even this does not work for you, maybe it's related to podman?

[bioinfornatics]

@li-boxuan about the python code (original issue)
Maybe that come from volume mounted indeed at beginning it was:

mkdir  janusgraph
# podamn or docker is same
podman run --rm -dt --name janusgraph_server -v "${PWD}"/janusgraph:/var/lib/janusgraph -p 8182:8182 docker.io/janusgraph/janusgraph:0.5.3

but the directory janusgraph do not own subdirectory data and index

So now without mounted volume that works

podman run --rm -dt --name janusgraph_server  --pod new:jgpod -p 0.0.0.0:8182:8182 docker.io/janusgraph/janusgraph:0.5.3

from gremlin_python import statics
from gremlin_python.structure.graph import Graph
from gremlin_python.process.graph_traversal import __
from gremlin_python.driver.driver_remote_connection import DriverRemoteConnection
graph = Graph()
connection = DriverRemoteConnection('ws://localhost:8182/gremlin', 'g')
# The connection should be closed on shut down to close open connections with connection.close()
g = graph.traversal().withRemote(connection)
# Reuse 'g' across the application
g.addV('person').property('name', 'hercules').property('age', 42).next()
herculesAge = g.V().has('name', 'hercules').values('age').next()
print(herculesAge)

about the second case with gremlin I reach as you the step 2, it was a fail just after with groovy statement. I have to do a try now without to mount the directory

Thanks again for your help it give me the strength to get a better understanding

[bioinfornatics]

ok I got it in fact it is a permission issue the directory janusgraph is by default 750 (from mkdir) so my uid is allowed to rwx but the uid into the container is not the same as mine so I have to change permission to 777

[li-boxuan]

Great to see it finally works for you!