Red Hat Bugzilla – Bug 986219
Unable to connect to postgresql-9.2 database with python-2.7 app.
Last modified: 2016-11-30 19:27:42 EST
Created attachment 775696 [details]
wsgi/application and wsgi/postgresql_factory.py
Description of problem:
I created a python-2.7 app, embedded a postgresql-9.2 cartridge and created a simple script that inserts test data into the database.
The script throws the following error:
"libpq.so.postgresql92-5: cannot open shared object file: No such file or directory" The script, "postgresql_factory" as well as wsgi/application are attached
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. rhc app create myapp python-2.7
2. rhc cartridge add postgresql-9.2 -a myapp
3. add attached files, git add . ; git commit & git push
4. access /postgresql url of your app
FILE.postgresql factory is not added to this app
libpq.so.postgresql92-5: cannot open shared object file: No such file or directory
reproduced on all devenv instances
Spent some time on this and gave up. Not sure if this is just a matter of specifying the LD_LIBRARY_PATH or not. Mrunal seemed to indicate that we may need to check that the correct version of the .so files are being loaded.
Thanks for reporting the issue.
The problem is that the LD_LIBRARY_PATH does not include the path to postgresql-9.2 libraries. Could you try adding rhis line:
to your pre start python script to get around it for right now?
We will work on a fix!
Hi, I've tried putting this command in ./.openshift/action_hooks/deploy with no good result, where is the "pre start python script".
After a while the libpq.so error disappears and now this error shows up:
ImportError at /
cannot import name utils
/var/lib/openshift/520161db5004468578000363/python/virtenv/lib/python2.7/site-packages/Django-1.4-py2.7.egg/django/db/backends/postgresql_psycopg2/base.py in <module>
8. from django.db import utils
(In reply to Juan P. Daza P. from comment #3)
> Hi, I've tried putting this command in ./.openshift/action_hooks/deploy with
> no good result, where is the "pre start python script".
You could create one hook scripts named pre_start_python in ./.openshift/action_hooks/ and add the following to the hook script:
The bug is fixed with the resolution in Comment #5.
1) create a python-2.7 app with postgresql-9.2 cartridge added
2) add the files in the attachment to the app's local repo, and enable psycopg2 support in its setup.py file.
3) create an executable hook named pre_start_python as Comment #5
4) push the changes
5) access <app_url>/postgresql
It showed "version 1" as expected.
(In reply to Zhe Wang from comment #6)
Can confirm this solutions works.
Reopening since I am not getting this with Python 2.7 and postgresl 9.2.
This is for the application that is supposed to work with the new book - please consider this an emergency patch.
[Fri Feb 07 13:48:12 2014] [error] [client 127.9.124.1] ImportError: libpq.so.postgresql92-5: cannot open shared object file: No such file or directory
You have permission to go into the gears and diagnose the error.
insultapp @ http://insultapp-osbeginnerbook.rhcloud.com/ (uuid: 52df5ed54382x)
Created: Jan 21 10:01 PM
Gears: 1 (defaults to small)
Git URL: ssh://firstname.lastname@example.org/~/git/insultapp.git/
Deployment: auto (on git push)
python-2.7 (Python 2.7)
Gears: Located with postgresql-9.2, cron-1.4
postgresql-9.2 (PostgreSQL 9.2)
Gears: Located with python-2.7, cron-1.4
Connection URL: postgresql://$OPENSHIFT_POSTGRESQL_DB_HOST:$OPENSHIFT_POSTGRESQL_DB_PORT
Database Name: insultapp
cron-1.4 (Cron 1.4)
Gears: Located with python-2.7, postgresql-9.2
I don't think it's appropriate to close a bug as "currentrelease" (implying that we fixed something) when the solution is really a workaround. Why are we not handling LD_LIBRARY_PATH elements like PATH elements?
Confirmed on Python 3.3 as well.
This is a production level issue, lets try to get a proper fix and put a hotfix out. I've dealt with LD_LIBRARY_PATH issues like this in community cartridges:
I know the shifters are running into issues with this now so it would be good to get a proper fix out.
I'm no longer able to reproduce this on devenv, the app in Oleg's attachment works fine and I got 'version 1'. Also no compilation issues.
Mike: There is a Trello card to multiple cartridges with isolated LD_LIBRARY_PATH (since we went throught this problem for Zend, Jenkins, Mysql...): https://trello.com/c/BB2errnd/31-handle-multiple-catridges-having-their-own-ld-library-path
It's fixed, verified on devenv_4357, please refer to the following results:
1. create a python-2.7 app with postgresql-9.2 cartridge added
2. add the files in the attachment to the app's local repo, and enable psycopg2 support in its setup.py file.
3. push the changes
4. access <app_url>/postgresql
at step 4: Met "version 1" on the webpage
The actual fix will be a part of:
chunchen you actually need to have an application that loads the driver otherwise it won't really test it.
Here is some example code that throws the error:
from random import choice
#get a connection to use in the DB calls. Only need a cursor because these connections are read only
conn = psycopg2.connect(database=os.environ['OPENSHIFT_APP_NAME'], user=os.environ['OPENSHIFT_POSTGRESQL_DB_USERNAME'],
cursor = conn.cursor()
#Clean up when done with the cursor and connection
conn = cursor.connection
return "Thou " + generate_insult() + "!"
return name + ", thou " + generate_insult() + "!"
first_adjs = ["artless", "bawdy", "beslubbering", "bootless", "churlish"]
second_adjs = ["base-court", "bat-fowling", "beef-witted", "beetle-headed", "boil-brained"]
nouns = ["apple-john", "baggage", "barnacle", "bladder", "boar-pig"]
return choice(first_adjs) + " " + choice(second_adjs) + " " + choice(nouns)
#Expects to be passed a psycopg2 cursor
#Using the solution found on this Stack Overflow page
cur.execute("select string from short_adjective offset random() * (select count(*) from short_adjective) limit 1;")
print "HERE IS THE RESULT of count :: " + str(cur.fetchone())
One other note for the workaround. If you are using python then the action_hook needs to be name pre_start_python
Steven, Oleg: The Trello card I'm currently working will allow this without any workarounds or hacks for non-scalable but also for scalable apps. I tested both Oleg's and your code and they both works. Stay tuned! :-)
Confirmed bug still exists for Python 2.7 and PostgreSQL 9.2, however workaround suggested in comment #5 works
Have verified on devenv_4916 with Oleg's and Steven's scripts, both works well, below are the steps using Steven's scripts(please correct if my steps are wrong):
1. Create a python-2.7 with postgresql-9.2
2. In app local repo, edit setup.py: add "psycopg2" to "install_requires"
3. Create a table short_adjective with column "username" and values "openshift" in psql
4. Add below codes to wsgi.py:
from random import choice
def application(environ, start_response):
elif environ['PATH_INFO'] == '/psql':
conn_str = "dbname=%s user=%s password=%s host=%s port=%s" % (
conn = psycopg2.connect(conn_str)
cur = conn.cursor()
cur.execute("select username from short_adjective offset random()")
response_body = str(cur.fetchone())
5. Git push the changes;
6. Access https://$appurl/psql, and can get the content I input in the table short_adjective successfully.
Below are the LD_LIBRARY_PATH returns in gear(which I didn't add like comment #5):
[myapp-d.dev.rhcloud.com 53ad361405636e0e38000025]\> get_gear_ld_library_path
[myapp-d.dev.rhcloud.com 53ad361405636e0e38000025]\> env | grep LD_LIBRARY_PATH