Fix create_db command of docker-entrypoint

[ariarijp]

Sometimes I get an error like below.

$ docker-compose -f docker-compose.yml run --rm server create_db
Creating network "redash_default" with the default driver
Creating redash_postgres_1 ...
Creating redash_redis_1 ...
Creating redash_postgres_1
Creating redash_redis_1 ... done
[2017-11-26 04:01:52,577][PID:1][INFO][root] Generating grammar tables from /usr/lib/python2.7/lib2to3/Grammar.txt
[2017-11-26 04:01:52,595][PID:1][INFO][root] Generating grammar tables from /usr/lib/python2.7/lib2to3/PatternGrammar.txt
Traceback (most recent call last):
  File "/app/manage.py", line 9, in <module>
    manager()
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 716, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/flask/cli.py", line 345, in main
    return AppGroup.main(self, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 696, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 1060, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 1060, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 889, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 534, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/click/decorators.py", line 17, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/flask/cli.py", line 229, in decorator
    return __ctx.invoke(f, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 534, in invoke
    return callback(*args, **kwargs)
  File "/app/redash/cli/database.py", line 10, in create_tables
    db.create_all()
  File "/usr/local/lib/python2.7/dist-packages/flask_sqlalchemy/__init__.py", line 972, in create_all
    self._execute_for_all_tables(app, bind, 'create_all')
  File "/usr/local/lib/python2.7/dist-packages/flask_sqlalchemy/__init__.py", line 964, in _execute_for_all_tables
    op(bind=self.get_engine(app, bind), **extra)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/sql/schema.py", line 3848, in create_all
    tables=tables)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1919, in _run_visitor
    with self._optional_conn_ctx_manager(connection) as conn:
  File "/usr/lib/python2.7/contextlib.py", line 17, in __enter__
    return self.gen.next()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1912, in _optional_conn_ctx_manager
    with self.contextual_connect() as conn:
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 2103, in contextual_connect
    self._wrap_pool_connect(self.pool.connect, None),
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 2142, in _wrap_pool_connect
    e, dialect, self)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1456, in _handle_dbapi_exception_noconnection
    exc_info
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/util/compat.py", line 202, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb, cause=cause)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 2138, in _wrap_pool_connect
    return fn()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 387, in connect
    return _ConnectionFairy._checkout(self)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 766, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 516, in checkout
    rec = pool._do_get()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 1138, in _do_get
    self._dec_overflow()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 1135, in _do_get
    return self._create_connection()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 333, in _create_connection
    return _ConnectionRecord(self)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 461, in __init__
    self.__connect(first_connect_check=True)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 651, in __connect
    connection = pool._invoke_creator(self)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 105, in connect
    return dialect.connect(*cargs, **cparams)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 392, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "/usr/local/lib/python2.7/dist-packages/psycopg2/__init__.py", line 164, in connect
    conn = _connect(dsn, connection_factory=connection_factory, async=async)
sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) could not connect to server: Connection refused
	Is the server running on host "postgres" (172.18.0.2) and accepting
	TCP/IP connections on port 5432?

I think create_db command should wait for PostgreSQL container to become available.

Thank you,

[ariarijp]

Hi @arikfr,

How is this PR?
Some our workshop attendees stuck on its error.
If you have other ideas, I will close this PR.

Thanks,

[arikfr]

Thank you for finding a solution to this issue! It's merged now. Sorry it took so long.