persist connection info from docker container

I'm using the pgadmin4 docker image from
https://hub.docker.com/r/dpage/pgadmin4/, which says to get help using this
mailing list.

I'd like to use the docker container and persist the data such that I don't
have to add my connection info to Postgres every time I restart it. How can
I do this?

Here's a more explicit list of what I'm doing:

1) Run the image as directed:
docker run -p 5050:80 \
-e "PGADMIN_DEFAULT_EMAIL=user(at)domain(dot)com" \
-e "PGADMIN_DEFAULT_PASSWORD=SuperSecret" \
-d dpage/pgadmin4
2) Visit http://localhost:5050
3) I'm asked to login, which I do using those environment variables, which
works
4) I see the pgAdmin website interface, and I must choose "Add New Server"
to access my server, and input my host, port, username, password, every
time. I don't want to repeat this. I'd like the connection information to
remain.

There are instructions on that same https://hub.docker.com/r/dpage/pgadmin4/
page that suggest to use this line as part of the docker command:

-v "/private/var/lib/pgadmin:/var/lib/pgadmin" \

However, if I do that, here's what happens:

1) Run the image as directed:
docker run -p 5050:80 \
-e "PGADMIN_DEFAULT_EMAIL=user(at)domain(dot)com" \
-e "PGADMIN_DEFAULT_PASSWORD=SuperSecret" \
-d dpage/pgadmin4
2) Visit http://localhost:5050
3) I'm shown an error:
Internal Server Error
The server encountered an internal error or misconfiguration and was
unable to complete your request.

Please contact the server administrator at root(at)localhost to inform them
of the time this error occurred, and the actions you performed just before
this error.

More information about this error may be available in the server error
log.

I finally figured out how to see the output of the docker logs to see what
was going on. It was complaining it had no access to
/var/lib/pgadmin/sessions, a directory which didn't exist. After I created
it, and refreshed my browser, the logs showed an error about the
/var/lib/pgadmin/storage directory not existing. Progress! So I created
that one manually. But now I'm stuck. Obviously I don't want to do this
forever... I need to give some permissions so it can do what it needs.
Here's the error message I'm left with when I tail/follow the docker logs:

OperationalError: (sqlite3.OperationalError) unable to open database file
mod_wsgi (pid=10): Target WSGI script '/var/www/pgadmin/pgAdmin4.wsgi'
cannot be loaded as Python module.
mod_wsgi (pid=10): Exception occurred processing WSGI script
'/var/www/pgadmin/pgAdmin4.wsgi'.
Traceback (most recent call last):
File "/var/www/pgadmin/pgAdmin4.wsgi", line 36, in <module>
from pgAdmin4 import app as application
File "/var/www/pgadmin/pgAdmin4.py", line 67, in <module>
app = create_app()
File "/var/www/pgadmin/pgadmin/__init__.py", line 306, in create_app
db_upgrade(app)
File "/var/www/pgadmin/pgadmin/setup/db_upgrade.py", line 25, in
db_upgrade
flask_migrate.upgrade(migration_folder)
File "/usr/lib/python2.7/site-packages/flask_migrate/__init__.py", line
244, in upgrade
command.upgrade(config, revision, sql=sql, tag=tag)
File "/usr/lib/python2.7/site-packages/alembic/command.py", line 254, in
upgrade
script.run_env()
File "/usr/lib/python2.7/site-packages/alembic/script/base.py", line 425,
in run_env
util.load_python_file(self.dir, 'env.py')
File "/usr/lib/python2.7/site-packages/alembic/util/pyfiles.py", line 81,
in load_python_file
module = load_module_py(module_id, path)
File "/usr/lib/python2.7/site-packages/alembic/util/compat.py", line 141,
in load_module_py
mod = imp.load_source(module_id, path, fp)
File "/var/www/pgadmin/pgadmin/setup/../../migrations/env.py", line 94,
in <module>
run_migrations_online()
File "/var/www/pgadmin/pgadmin/setup/../../migrations/env.py", line 79,
in run_migrations_online
connection = engine.connect()
File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line
2018, in connect
return self._connection_cls(self, **kwargs)
File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line
72, in __init__
if connection is not None else engine.raw_connection()
File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line
2104, in raw_connection
self.pool.unique_connection, _connection)
File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line
2078, in _wrap_pool_connect
e, dialect, self)
File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line
1405, in _handle_dbapi_exception_noconnection
exc_info
File "/usr/lib64/python2.7/site-packages/sqlalchemy/util/compat.py", line
202, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb, cause=cause)
File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line
2074, in _wrap_pool_connect
return fn()
File "/usr/lib64/python2.7/site-packages/sqlalchemy/pool.py", line 318,
in unique_connection
return _ConnectionFairy._checkout(self)
File "/usr/lib64/python2.7/site-packages/sqlalchemy/pool.py", line 713,
in _checkout
fairy = _ConnectionRecord.checkout(pool)
File "/usr/lib64/python2.7/site-packages/sqlalchemy/pool.py", line 480,
in checkout
rec = pool._do_get()
File "/usr/lib64/python2.7/site-packages/sqlalchemy/pool.py", line 1151,
in _do_get
return self._create_connection()
File "/usr/lib64/python2.7/site-packages/sqlalchemy/pool.py", line 323,
in _create_connection
return _ConnectionRecord(self)
File "/usr/lib64/python2.7/site-packages/sqlalchemy/pool.py", line 449,
in __init__
self.connection = self.__connect()
File "/usr/lib64/python2.7/site-packages/sqlalchemy/pool.py", line 607,
in __connect
connection = self.__pool._invoke_creator(self)
File
"/usr/lib64/python2.7/site-packages/sqlalchemy/engine/strategies.py", line
97, in connect
return dialect.connect(*cargs, **cparams)
File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/default.py",
line 385, in connect
return self.dbapi.connect(*cargs, **cparams)
OperationalError: (sqlite3.OperationalError) unable to open database file

Any ideas?

Thanks!
Ty