could not translate host name "postgres" to address: Name does not resolve [Docker swarm]

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twinmegami

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Feb 23, 2018, 10:05:05 PM2/23/18

to Django users

I am using docker swarm to set env

```

- DATABASE_URL=postgres://basin:basin_pa44@postgres:5432/demo

```

I confirmed two host can reach each other. And directly using psycopg2 was fine:

```

>>> import psycopg2

>>> conn = psycopg2.connect('postgres://basin:basin_pa44@postgres:5432/demo')

>>> conn

<connection object at 0x7f8c71179b48; dsn: 'user=basin host=postgres password=xxx port=5432 dbname=d$

mo', closed: 0>

>>> conn

KeyboardInterrupt

>>> cur = conn.cursor()

>>>

>>> cur.execute("""SELECT datname from pg_database""")

>>> rows = cur.fetchall()

>>> print "\nShow me the databases:\n"

Show me the databases:

>>> for row in rows:

... print " ", row[0]

...

postgres

demo

template1

template0

```

django database settings :

```

DATABASES = {

'default': env.db(),

}

```

env:

```

>>> import environ

>>> env = environ.Env()

>>> env

<environ.environ.Env object at 0x7f8c6cf949d0>

>>> env.db()

{'ENGINE': 'django.db.backends.postgresql_psycopg2', 'NAME': 'demo', 'HOST': 'postgres', 'USER': 'bas

in', 'PASSWORD': 'basin_pa44', 'PORT': 5432}

```

error:

```

I am using docker swarm to set env

```

- DATABASE_URL=postgres://basin:basin_pa44@postgres:5432/demo

```

I confirmed two host can reach each other. And directly using psycopg2 was fine:

```

>>> import psycopg2

>>> conn = psycopg2.connect('postgres://basin:basin_pa44@postgres:5432/demo')

>>> conn

<connection object at 0x7f8c71179b48; dsn: 'user=basin host=postgres password=xxx port=5432 dbname=d$

mo', closed: 0>

>>> conn

KeyboardInterrupt

>>> cur = conn.cursor()

>>>

>>> cur.execute("""SELECT datname from pg_database""")

>>> rows = cur.fetchall()

>>> print "\nShow me the databases:\n"

Show me the databases:

>>> for row in rows:

... print " ", row[0]

...

postgres

demo

template1

template0

```

Database settings :

```

DATABASES = {

'default': env.db(),

}

```

env:

```

>>> import environ

>>> env = environ.Env()

>>> env

<environ.environ.Env object at 0x7f8c6cf949d0>

>>> env.db()

{'ENGINE': 'django.db.backends.postgresql_psycopg2', 'NAME': 'demo', 'HOST': 'postgres', 'USER': 'bas

in', 'PASSWORD': 'basin_pa44', 'PORT': 5432}

```

error:

```

I am using docker swarm to set env

```

- DATABASE_URL=postgres://basin:basin_pa44@postgres:5432/demo

```

I confirmed two host can reach each other. And directly using psycopg2 was fine:

```

>>> import psycopg2

>>> conn = psycopg2.connect('postgres://basin:basin_pa44@postgres:5432/demo')

>>> conn

<connection object at 0x7f8c71179b48; dsn: 'user=basin host=postgres password=xxx port=5432 dbname=d$

mo', closed: 0>

>>> conn

KeyboardInterrupt

>>> cur = conn.cursor()

>>>

>>> cur.execute("""SELECT datname from pg_database""")

>>> rows = cur.fetchall()

>>> print "\nShow me the databases:\n"

Show me the databases:

>>> for row in rows:

... print " ", row[0]

...

postgres

demo

template1

template0

```

Database settings :

```

DATABASES = {

'default': env.db(),

}

```

env:

```

>>> import environ

>>> env = environ.Env()

>>> env

<environ.environ.Env object at 0x7f8c6cf949d0>

>>> env.db()

{'ENGINE': 'django.db.backends.postgresql_psycopg2', 'NAME': 'demo', 'HOST': 'postgres', 'USER': 'bas

in', 'PASSWORD': 'basin_pa44', 'PORT': 5432}

```

error:

```

I am using docker swarm to set env

```

- DATABASE_URL=postgres://basin:basin_pa44@postgres:5432/demo

```

I confirmed two host can reach each other. And directly using psycopg2 was fine:

```

>>> import psycopg2

>>> conn = psycopg2.connect('postgres://basin:basin_pa44@postgres:5432/demo')

>>> conn

<connection object at 0x7f8c71179b48; dsn: 'user=basin host=postgres password=xxx port=5432 dbname=d$

mo', closed: 0>

>>> conn

KeyboardInterrupt

>>> cur = conn.cursor()

>>>

>>> cur.execute("""SELECT datname from pg_database""")

>>> rows = cur.fetchall()

>>> print "\nShow me the databases:\n"

Show me the databases:

>>> for row in rows:

... print " ", row[0]

...

postgres

demo

template1

template0

```

Database settings :

```

DATABASES = {

'default': env.db(),

}

```

env:

```

>>> import environ

>>> env = environ.Env()

>>> env

<environ.environ.Env object at 0x7f8c6cf949d0>

>>> env.db()

{'ENGINE': 'django.db.backends.postgresql_psycopg2', 'NAME': 'demo', 'HOST': 'postgres', 'USER': 'bas

in', 'PASSWORD': 'basin_pa44', 'PORT': 5432}

```

error:

```

bidspy_demo.1...@nd4.csp.ali | You have 22 unapplied migration(s). Your project may not work properly until you apply the migrations for app(s): admin,

uth, authtools, contenttypes, easy_thumbnails, orders, profiles, sessions.

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/utils/autoreload.py", line 227, in wrapper

bidspy_demo.1...@nd4.csp.ali | Run 'python manage.py migrate' to apply them.

bidspy_demo.1...@nd4.csp.ali | February 24, 2018 - 01:42:11

bidspy_demo.1...@nd4.csp.ali | Django version 1.11.3, using settings 'demo.settings.development'

bidspy_demo.1...@nd2.csp.ali | fn(*args, **kwargs)

bidspy_demo.1...@nd4.csp.ali | Starting development server at http://0.0.0.0:8000/

bidspy_demo.1...@nd4.csp.ali | Quit the server with CONTROL-C.

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line 128, in inner_run

bidspy_demo.1...@nd2.csp.ali | self.check_migrations()

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/core/management/base.py", line 422, in check_migrations

bidspy_demo.1...@nd2.csp.ali | executor = MigrationExecutor(connections[DEFAULT_DB_ALIAS])

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/migrations/executor.py", line 20, in __init__

bidspy_demo.1...@nd2.csp.ali | self.loader = MigrationLoader(self.connection)

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/migrations/loader.py", line 52, in __init__

bidspy_demo.1...@nd2.csp.ali | self.build_graph()

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/migrations/loader.py", line 209, in build_graph

bidspy_demo.1...@nd2.csp.ali | self.applied_migrations = recorder.applied_migrations()

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/migrations/recorder.py", line 65, in applied_migrations

bidspy_demo.1...@nd2.csp.ali | self.ensure_schema()

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/migrations/recorder.py", line 52, in ensure_schema

bidspy_demo.1...@nd2.csp.ali | if self.Migration._meta.db_table in self.connection.introspection.table_names(self.connection.cursor()):

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/backends/base/base.py", line 254, in cursor

bidspy_demo.1...@nd2.csp.ali | return self._cursor()

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/backends/base/base.py", line 229, in _cursor

bidspy_demo.1...@nd2.csp.ali | self.ensure_connection()

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/backends/base/base.py", line 213, in ensure_connection

bidspy_demo.1...@nd2.csp.ali | self.connect()

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/utils.py", line 94, in __exit__

bidspy_demo.1...@nd2.csp.ali | six.reraise(dj_exc_type, dj_exc_value, traceback)

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/backends/base/base.py", line 213, in ensure_connection

bidspy_demo.1...@nd2.csp.ali | self.connect()

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/backends/base/base.py", line 189, in connect

bidspy_demo.1...@nd2.csp.ali | self.connection = self.get_new_connection(conn_params)

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/django/db/backends/postgresql/base.py", line 176, in get_new_connection

bidspy_demo.1...@nd2.csp.ali | connection = Database.connect(**conn_params)

bidspy_demo.1...@nd2.csp.ali | File "/usr/lib/python2.7/site-packages/psycopg2/__init__.py", line 130, in connect

bidspy_demo.1...@nd2.csp.ali | conn = _connect(dsn, connection_factory=connection_factory, **kwasync)

bidspy_demo.1...@nd2.csp.ali | django.db.utils.OperationalError: could not translate host name "postgres" to address: Name does not resolve

bidspy_demo.1...@nd2.csp.ali |

```

twinmegami

unread,

Feb 24, 2018, 2:03:54 AM2/24/18

to Django users

Ok, I found the problem is depends_on not work on swarm mode

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