Re: Trying to solve a SocketError [Errno 13] Permission with PL/Python in PostgreSQL 9.3

On 05/23/2015 04:16 PM, Marcos Ortiz wrote:
>
>
> On 23/05/15 19:09, Adrian Klaver wrote:
>> On 05/23/2015 03:51 PM, Marcos Ortiz wrote:
>>>
>>>
>>> On 23/05/15 18:40, Adrian Klaver wrote:
>>>> On 05/23/2015 03:27 PM, Marcos Ortiz wrote:
>>>>> Regards to all the list.
>>>>> First all the info about the system:
>>>>>
>>>>> O.S: CentOS 7 64 bits
>>>>> PostgreSQL version:
>>>>>
>>>>> SELECT version();
>>>>> version
>>>>> --------------------------------------------------------------------------------------------------------------
>>>>>
>>>>>
>>>>>
>>>>> PostgreSQL 9.2.7 on x86_64-redhat-linux-gnu, compiled by gcc (GCC)
>>>>> 4.8.2 20140120 (Red Hat 4.8.2-16), 64-bit
>>>>> (1 row)
>>>>>
>>>>> Neo4j version: 2.1.M
>>>>> Py2neo version: 2.0.8
>>>>> Python version:
>>>>> python
>>>>> Python 2.7.5 (default, Jun 17 2014, 18:11:42)
>>>>> [GCC 4.8.2 20140120 (Red Hat 4.8.2-16)] on linux2
>>>>>
>>>>> Now the problem:
>>>>>
>>>>> We are working here to integrate PostgreSQL with Neo4j through
>>>>> PL/Python
>>>>> using the py2neo module for it, and when we want to send sentences to
>>>>> Neo4j using port 7474, the executed code raises a SocketError
>>>>> [Errno 13]
>>>>> Permission denied.
>>>>
>>>> Well first in the code below, if I am following correctly, the socket
>>>> is 37474.
>>> Yes, Adrian. Sorry for that, the correct port is 7474. I just was
>>> testing with higher ports to
>>> see if the error persisted.
>>>>
>>>>
>>>>>
>>>>> I tested the same code in a normal python script outside of
>>>>> PostgreSQL,
>>>>> and it works well, but the problem is when I use the code inside
>>>>> PostgreSQL with PL/Python.
>>>>
>>>> Second the plpythonu code is running as the postgres user, so does
>>>> that user have permissions on the socket.
>>> Did you mean the socket created by Neo4j's server right?
>>> For that reason, I created a group in the system for this named
>>> supervisor, where neo4j/postgres users are members.
>>> So, if I find the socket file for Neo4j-server, changing permissions
>>> could solve the problem. Right?
>>
>> Not sure, but a quick search found that py2neo uses the neo4j REST API
>> and that API has authorization parameters:
>>
>> http://neo4j.com/docs/stable/security-server.html
>>
>> Have you gone through the above?
> Yes, Adrian. py2neo installs a tool called neoauth, which can be used to
> create users with their respective passwords.
> For that reason, I use this way to create the graph:
>
> graph = Graph("http://neo4j:neo4j(at)10(dot)8(dot)45(dot)136:7474/db/data")
> using the user neo4j and its pass neo4j

From a quick look at the neo4j security docs, it seems the server by
default only accepts connections from localhost. So where is the neo4j
server in relation to the Postgres server and the stand alone Python
script that runs?
>
>>
>>
>>> Neo4j is a Java-based platform.
>>>>
>>>>> This is the code of a simple function to search a node in the Neo4j
>>>>> graph:
>>>>>
>>>>> CREATE OR REPLACE FUNCTION search_professor_node(nombre_prof text)
>>>>> RETURNS text AS
>>>>> $BODY$
>>>>> from py2neo import Graph
>>>>> from py2neo.cypher import CypherTransaction
>>>>>
>>>>> graph = Graph("http://neo4j:neo4j(at)10(dot)8(dot)45(dot)136:37474/db/data")
>>>>> tx = graph.cypher.begin()
>>>>> statement = "MATCH (pf:Professor) WHERE pf.nombre = {name} RETURN
>>>>> pf;" ,
>>>>> tx.append(statement, parameters={'name': nombre_prof})
>>>>> professor= tx.commit()
>>>>> $BODY$
>>>>> LANGUAGE plpythonu VOLATILE
>>>>> COST 100;
>>>>>
>>>>> and it can be used:
>>>>> SELECT search_professor_node('Max');
>>>>>
>>>>> The completed error is:
>>>>>
>>>>> ********** Error **********
>>>>>
>>>>> ERROR: py2neo.packages.httpstream.http.SocketError: Permission denied
>>>>> SQL state: XX000
>>>>> Context: Traceback (most recent call last):
>>>>> PL/Python function "search_professor_node", line 6, in <module>
>>>>> tx = graph.cypher.begin()
>>>>> PL/Python function "search_professor_node", line 666, in cypher
>>>>> PL/Python function "search_professor_node", line 212, in metadata
>>>>> PL/Python function "search_professor_node", line 257, in get
>>>>> PL/Python function "search_professor_node", line 965, in get
>>>>> PL/Python function "search_professor_node", line 942, in
>>>>> __get_or_head
>>>>> PL/Python function "search_professor_node", line 432, in submit
>>>>> PL/Python function "search_professor_node", line 361, in submit
>>>>> PL/Python function "search_professor_node"
>>>>>
>>>>> Thanks a lot for your time, and I hope to find a suitable solution
>>>>> for it.
>>>>>
>>>>>
>>>>
>>>>
>>>
>>> --
>>> Marcos Ortiz <http://about.me/marcosortiz>, Sr. Product Manager (Data
>>> Infrastructure) at UCI
>>> @marcosluis2186 <http://twitter.com/marcosluis2186>
>>>
>>>
>>
>>
>
> --
> Marcos Ortiz <http://about.me/marcosortiz>, Sr. Product Manager (Data
> Infrastructure) at UCI
> @marcosluis2186 <http://twitter.com/marcosluis2186>
>
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com