Re: Could not resolve host name error in psycopg2

Thank you, I've changed it to use the server's IP address since, so I'll
wait to see if the error happens again.

On Fri, 17 Apr 2020 at 09:00, Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
wrote:

> On 4/16/20 5:38 PM, derwin theduck wrote:
> > We have been getting this error intermittently (about once a week) in
> > Django with channels since switching from a local database server to a
> > hosted one:
> >
> > could not translate host name "timescaledb" to address: Name or service
> > not known
> >
> > Connecting directly to the server with psycopg2 in the python
> > interpreter works ok:
> >
> > >>> import psycopg2 as pg
> > >>> pg.__version__
> > '2.7.7 (dt dec pq3 ext lo64)'
> > >>> conn = pg.connect(host='timescaledb', database=*, user=*,
> > password=*) >>> conn.server_version
> > 110005
>
> Well I'm go out on a limb and say there is some sort of DNS resolution
> issue going on.
>
> >
> > The resident database / network expert maintains that everything is ok
> > on the networking side, and that django, once it establishes a
> > connection, should not be attempting to reconnect.
>
> Huh? Leaving open connections is not considered a good thing. In other
> words a connection should last for as long as it takes to get it's task
> done and then it should close.
>
> >
> > The problem happens not on startup, but in the middle of the day after
> > processing transactions without any issues for several hours.
> >
> > Any idea how to go about troubleshooting / fixing this? :'(
> >
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/db/models/query.py",
> > line 276, in __iter__)
> > ( self._fetch_all())
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/db/models/query.py",
> > line 1261, in _fetch_all)
> > ( self._result_cache = list(self._iterable_class(self)))
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/db/models/query.py",
> > line 57, in __iter__)
> > ( results = compiler.execute_sql(chunked_fetch=self.chunked_fetch,
> > chunk_size=self.chunk_size))
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/db/models/sql/compiler.py",
>
> > line 1135, in execute_sql)
> > ( cursor = self.connection.cursor())
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/utils/asyncio.py",
> line
> > 24, in inner)
> > ( return func(*args, **kwargs))
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/db/backends/base/base.py",
>
> > line 260, in cursor)
> > ( return self._cursor())
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/db/backends/base/base.py",
>
> > line 236, in _cursor)
> > ( self.ensure_connection())
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/utils/asyncio.py",
> line
> > 24, in inner)
> > ( return func(*args, **kwargs))
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/db/backends/base/base.py",
>
> > line 220, in ensure_connection)
> > ( self.connect())
> > ( File
> > "/home/dduck/.local/lib/python3.7/site-packages/django/db/utils.py",
> > line 90, in __exit__)
> > ( raise dj_exc_value.with_traceback(traceback) from exc_value)
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/db/backends/base/base.py",
>
> > line 220, in ensure_connection)
> > ( self.connect())
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/utils/asyncio.py",
> line
> > 24, in inner)
> > ( return func(*args, **kwargs))
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/db/backends/base/base.py",
>
> > line 197, in connect)
> > ( self.connection = self.get_new_connection(conn_params))
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/utils/asyncio.py",
> line
> > 24, in inner)
> > ( return func(*args, **kwargs))
> > ( File
> >
> "/home/dduck/.local/lib/python3.7/site-packages/django/db/backends/postgresql/base.py",
>
> > line 185, in get_new_connection)
> > ( connection = Database.connect(**conn_params))
> > ( File
> > "/usr/local/lib64/python3.7/site-packages/psycopg2/__init__.py", line
> > 130, in connect)
> > ( conn = _connect(dsn, connection_factory=connection_factory,
> > **kwasync))
> > ( could not translate host name "timescaledb" to address: Name or
> > service not known)
> >
> >
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com
>